␥. See gamma. gadodiamide hydrate.

CAS: 122795-43-1. mf: C

GdN

•xH

Hazard: Low toxicity. A reproductive hazard.

G. See guanine

g. (1) Abbreviation of gram, (2) acceleration due to

gadolinium.

gravity.

CAS: 7440-54-2. Gd. A rare-earth element of the

lanthanide series, atomic number 64, group IIIB of

␮g. Abbreviation of microgram. the periodic table, aw 157.25, valence of 3; seven

natural isotopes.

Properties: Lustrous metal. D 7.87, mp 1312C, bp

“G-30” [Haynes]. TM for a high-strength,

3000C; reacts slowly with water. Soluble in dilute

nickel-based alloy with outstanding corrosion resis-

acid; insoluble in water. Exhibits a high degree of

tance to strong oxidizing media, and excellent resis-

magnetism, especially at low temperatures; salts are

tance to localized corrosion and stress corrosion

colorless; has highest neutron absorption cross-sec-

cracking while maintaining ease of welding and

tion of any known element; has superconductive

fabrication.

properties, burns in air to form the oxide. Combus-

Available forms: Sheet, plate, bars, rods, welding

tible.

electrodes, and wire.

Derivation: (1) Reduction of the fluoride with calci-

Use: Fabrication into all types of process equipment.

um, (2) electrolysis of the chloride with sodium

chloride or potassium chloride in an iron pot that

“G-942” [Du Pont]. TM for an aqueous solu-

serves as an anode and graphite cathode.

tion of the partial sodium salt of a polymeric carbox-

Grade: Ingots, lumps, turnings, powder up to

ylic acid.

99.9+% pure.

Use: Tanning agent.

Use: Neutron shielding, garnets in microwave filters,

phosphor activator, catalyst, scavenger for oxygen

Ga. Symbol for gallium.

in titanium production.

GABA. Abbreviation for ␥-aminobutyric acid.

gadolinium chloride. GdCl

•xH

O. Colorless

See aminobutyric acid.

crystals, soluble in water, purities up to 99.9%.

Use: Gadolinium sponge metal, by contact with a

Gabriel-Colman rearrangement. Forma-

reducing metal vapor; source of gadolinium.

tion of isoquinoline derivatives by the action of

sodium ethoxide on phthalimidoacetic esters.

gadolinium fluoride. GdF

•2H

O. Available

up to 99.9% purity.

Gabriel ethylenimine method. Formation

Properties: Semisolid mass.

of ethylenimines (aziridines) by elimination of hy-

Hazard: Toxic material. TLV: 2.5 mg(F)/m

drogen halides from aliphatic vicinal haloamines

Use: Source of gadolinium.

with alkali. The method can be extended to the

preparation of five- and six-membered ring amines.

gadolinium nitrate. Gd(NO

)

•xH

O. Color-

less crystals, soluble in water, decomposes at 110C,

Gabriel synthesis. Conversion of alkyl halides

purities up to 99.9% gadolinium salt.

to primary amines by treatment with potassium

Hazard: Fire risk in contact with organic materials.

phthalimide and hydrolysis of the N-alkylphthali-

mides formed.

gadolinium oxalate. Gd

)

•10H

G acid. (2-naphthol-6,8-disulfonic acid).

Properties: White powder. Insoluble in water;

slightly soluble in acids; loses 6H

O at 110C.

Available forms: Purities up to 99.9% gadolinium

salt.

gadolinium oxide. Gd

. Properties: White- to

cream-colored powder, d 7.41, mp 2330C, insoluble

in water, soluble in acids to form the corresponding

Properties: White needles. Soluble in water. salts, hygroscopic, absorbs carbon dioxide from the

Derivation: Sulfonation of ␤-naphthol. air, purities up to 99.8% gadolinium oxide.

See Schaeffer acid. Derivation: Calcination of gadolinium salts, liquid/

Use: Azo dye intermediate. liquid ion-exchange separation.

592

593 GALLIUM ARSENIDE

Use: Neutron shields; catalysts; dielectric ceramics; metallic luster, good cubic cleavage. D 7.4–7.6,

Mohs hardness 2.5. Soluble in strong nitric acid, in

filament coatings; special glasses; TV phosphor ac-

excess of hot hydrochloric acid.

tivator; lasers, masers, and telecommunication; lab-

Occurrence: Western U.S., Canada, Africa, South

oratory reagent.

America.

Use: Chief ore of lead, frequently recovered for the

gadolinium sulfate. Gd

(SO

)

•8H

silver it sometimes contains.

Properties: Colorless crystals. D 3.01 (15C), purities

up to 99.9% gadolinium salt. Slightly soluble in hot

water; more soluble in coldwater.

“Galex” [Natrochem]. TM for dispropor-

Use: Cryogenic research; the selenide is used in ther-

tioned gum rosin or wood rosin.

moelectric generating devices.

Properties: Stable. Softening point 64–72C, acid no.

150−170 degrees.

gafamide coa. See coconut amine oil con-

Use: Adhesives, extender in rubber formulations.

densate.

gallic acid. (3,4,5-trihydroxybenzoic acid).

“GAF” Carbonyl Iron Powders

CAS: 149-91-7. C

(OH)

[International Specialty]. TM for micro-

scopic spheres of extremely pure iron. Produced in

11 carefully controlled grades ranging in particle

size from 3 to 20 microns in diameter. The iron

content of some types is as high as 99.5%.

Use: High-frequency cores for radio, telephone, tele-

vision, short-wave transmitters, radar receivers, di-

rection finders; alloying agents; catalysts; powder

metallurgy; magnetic fluids.

Properties: Colorless or slightly yellow crystalline

needles or prisms. D 1.694, mp 222–240C. Soluble

Gal. Abbreviation for galactose.

in alcohol and glycerol; sparingly soluble in water

and ether.

d-galactosamine hydrochloride. (2-amino-

Derivation: Action of mold on solutions of tannin or

2-dioxy-d-galactose).

by boiling the latter with strong acid or caustic soda.

CAS: 1772-03-8. C

ClNO

Use: Photography, writing ink, dyeing, manufacture

Properties: Crystalline solid. Mw 215.64, mp

of pyrogallol, tanning agent and manufacture of

182−185C (decomposes).

tannins, paper manufacture, pharmaceuticals, en-

Derivation: Amino sugar isolated from chondroitin

graving and lithography, analytical reagent.

sulfate.

gallium.

galactose.

CAS: 7440-55-3. Ga. Metallic element of atomic

CAS: 59-23-4. C

. A monosaccharide com-

number 31, group IIIA of the periodic table, aw

monly occurring in milk sugar or lactose.

69.72, valences of 2, 3; two stable isotopes.

Properties: White crystals. Mp 165–168C. Soluble

Properties: Silvery-white liquid at room tempera-

in hot water and pyridine; slightly soluble in glyc-

ture. Mp 29.7C, bp 2403C,; may be undercooled to

erol.

almost 0C without solidifying, d 5.9 (25C). More

Derivation: By acid hydrolysis of lactose.

dense as a liquid than as a solid. Soluble in acid,

Use: Organic synthesis, medicine (diagnostic aid).

alkali; slightly soluble in mercury. Reacts with most

metals at high temperatures.

␣-galactosidase.

Grade: Up to 99.9999% purity.

Properties: Derived from Mortierella vinaceae var.

Occurrence: Prepared commercially from zinc ores

raffinoseutilizer.

and bauxite.

Use: Food additive.

Derivation: Extraction of gallium as gallium chlo-

ride by ethyl ether or isopropyl ether and subsequent

D(+)-galacturonic acid. COOH(CH

CHO.

electrodeposition from an alkaline gallium oxide

A major constituent of plant pectins. It exhibits mu-

solution.

tarotation, having both an ␣ and a ␤ form.

Use: The metal has no significant commercial uses.

Properties: The ␣ form melts with decomposition at

Its compounds are used as semiconductors.

159–160C. Soluble in water, slightly soluble in hot

alcohol; insoluble in ether.

gallium antimonide. GaSb. Available in an

Derivation: Hydrolysis of pectins.

electronic grade.

Use: Biochemical research.

Use: Semiconducting devices.

galena. (galenite; lead glance).

CAS: 1314-87-0. PbS. Natural lead sulfide.

gallium arsenide.

Properties: Lead gray in color, lead-gray streak, CAS: 1303-00-0. GaAs.

594GALLIUM OXIDES

Properties: Crystals. Mp 1238C. Electrolumines-

galvanizing. Coating of a ferrous metal by pass-

cent in infrared light.

ing it through a bath of molten zinc or by electrode-

Grade: Ingots, polycrystalline form in high-purity

position of zinc. In the former process, the iron and

electronic grade, single crystals. Often alloyed with

zinc combine to form an intermetallic compound at

gallium phosphide or indium arsenide.

the interface, the outer surface being relatively pure

Hazard: Toxic metal.

zinc, which crystallizes as it cools to form the char-

Use: Semiconductor in light-emitting diodes for tele-

acteristic spangle. The electrodeposition method

phone dials, injection lasers, solar cells, magnetore-

gives a uniform surface that may be either dull or

sistance devices, thermistors, microwave genera-

bright. Duration of corrosion protection is directly

tion.

related to the thickness of the zinc coating.

See arsenic.

See sacrificial protection.

“Galvoline” [Dow]. TM for a cored magne-

gallium oxides. The sesquioxide, Ga

, and

sium ribbon used as a continuous anode for the

suboxide, Ga

O, are known. Both are stable at ordi-

cathode protection of buried pipelines and other

nary temperatures.

metal structures. Combustible.

See gallium sesquioxide.

“Galvomag” [Dow]. TM for magnesium alloy

gallium phosphide. GaP.

composition used in anodes in cathodic protection.

Properties: Pale-orange, transparent crystals or

whiskers up to 2 cm long, made by vapor phase

“Galvorod” [Dow]. TM for a cored magne-

reaction at relatively low temperatures between

sium rod used as an anode in the cathodic protection

phosphorus and gallium suboxide. These crystals

of water-heater tanks. Combustible.

are intermediate between normal semiconductors

and insulators or phosphors. They operate over a

gamete. A sex cell (egg or sperm) that carries half

temperature range of −55 to 500C. Gallium phos-

the normal complement of chromosomes and com-

phide is electroluminescent in visible light.

bines with another sex cell to produce a new individ-

Grade: Polycrystalline form in high-purity electron-

ual possessing the normal complement.

ic grade, single crystals, whiskers.

Use: Semiconducting devices.

gametes. Reproductive cells (sperm or egg)

which are haploid.

gallium sesquioxide. Ga

Properties: (␣ form) White crystals. D 6.44, mp

gametocide. A substance that can control polli-

1900C, changes to ␤ form at 600C. (␤ form) white

nation of plants by selectively killing plant sex cells

crystals. D 5.88. Both forms are insoluble in hot

(gametes). Some suggested gametocides are maleic

acid.

hydrazide and sodium-␣,␤-dichloroisobutyrate.

Grade: High-purity electronic.

Use: Spectroscopic analysis.

gametophyte. The haploid stage in the life cycle

of an organism undergoing alternations of genera-

gallocyanine. (CI 51030). C

ClN

tions. The gametophyte is multicellular and mitoti-

Properties: Greenish solid. Insoluble in water; solu-

cally produces gametes. In plants, the gametophyte

ble in alcohol, glacial acetic acid, alkali carbonate,

nourishes the zygote and young sporophyte.

and concentrated hydrochloric acid.

Derivation: Reaction of gallic acid with nitrosodi-

gamma. (␥). A prefix having meanings analo-

methylaniline.

gous to those of ␣, namely, to designate locations of

Use: Analytical reagent for lead, dye, and biological

substituents in a compound or a particular form or

stain.

modification of an organic substance (␥-globulin) or

a metal crystal. It also identifies the most intense

gallotannic acid. See tannic acid.

form of short-wave radiation.

See gamma ray.

galls. (nutgalls). Excrescences on various kinds

of oak trees resulting from the deposition of insect

gamma-acid. See ␥-acid.

eggs.

Grade: The best grades (55–60% tannic acid) come

gamma globulin. ␥ globulin.

from Iran, Syria, Turkey, and Tripoli.

See globulin.

Use: Source of gallic and gallotanic acids, leather

tanning, writing inks, medicine, textile printing,

gamma ray. (␥). Electromagnetic radiation of

pharmaceuticals.

extremely short wavelength and intensely high ener-

gy. ␥ rays originate in the atomic nucleus; they

“Galvan” [Cabot]. TM for battery and electri- usually accompany ␣ and ␤ emission, as in the decay

cally conductive carbon black. of radium, and always accompany fission. ␥ rays are

595 GAS BLACK

extremely penetrating and are absorbed by dense

gardenia yellow.

materials like lead and depleted uranium. CAS: 94238-00-3.

Hazard: Exposure to ␥ radiation may be lethal. Com- Hazard: Moderately toxic by ingestion.

plete protection is essential. Source: Natural product.

Use: To initiate chemical syntheses (ethyl bromide)

and cross-linking of polyethylene and other poly-

gardrin. See enprostil.

mers; biochemical research; food preservation; ana-

lytical chemistry.

garlic oil.

See X ray; radiation.

CAS: 8000-78-0.

Hazard: Moderately toxic by ingestion.

gamma-ray spectroscopy. (␥-ray spectros-

Source: Natural product.

copy). An analytical technique involving the use of

␥ radiation, which is emitted from radioactive nuclei

“Garlon” [Dow]. TM for herbicides containing

in discrete energies. The spectrum of energies and

water-soluble salts or oil-soluble esters of 3,5,6-tri-

the relative intensities of the ␥ rays often character-

chloro-2-pyridyloxyacetic acid.

ize the radionuclide that emits them; these are deter-

mined by ␥-ray spectroscopy. It is possible to identi-

garnet, natural. A group of silicate minerals.

fy quantitatively the elements present by their

Garnets in nature are usually composed of a mix of

characteristic ␥-ray spectra, as well as to determine

various garnet subspecies.

radioactive decay rates.

Use: Abrasive, blast cleaning of buildings.

“Ganex” [International Specialty]. TM for

garnet, synthetic. Single-crystal garnets de-

a series of modified polyvinylpyrrolidone-based

signed, by the introduction of bismuth, calcium, and

products. Available in a wide range of physical

vanadium, for microwave devices such as low-fre-

forms, from liquid to waxy solid to granular solid.

quency ferrimagnetic resonators. Special yttrium,

Used as emollients and lubricity additives, dispers-

iron, and aluminum garnets are used in lasers and

ing and suspending agents, pour-point depressants,

electronic devices.

sizing additives.

garnierite. (Ni, Mg)

(OH)

•H

O. A natural

ganglefene.

nickel-magnesium silicate, occurring as a natural

CAS: 299-61-6. mf: C

alteration of magnesium silicate rocks. A nickel ore.

Hazard: Moderately toxic.

gas. (↑). A state of matter characterized by very

gangliosides. Sphingolipids containing complex

low density and viscosity (relative to liquids and

oligosaccharides as head groups.

solids), comparatively great expansion and contrac-

tion with changes in pressure and temperature, abili-

gangue. The minerals and rock mined with a

ty to diffuse readily into other gases, and ability to

metallic ore but valueless in themselves or used only

occupy with almost complete uniformity the whole

as a by-product. They are separated from the ore in

of any container. Gases may be either elements (ar-

the milling and extraction processes, often as slag.

gon) or compounds (carbon dioxide); elemental

Common gangue materials are quartz, calcite, li-

gases may be monatomic (helium), diatomic (chlo-

monite, feldspar, pyrite, etc.

rine), or triatomic (ozone). All exist in the gaseous

state at standard temperature and pressure but can be

“Gantrez” AN [International Specialty].

liquefied by pressure. The most abundant gases on

TM for an interpolymer of methyl vinyl ether and

earth are oxygen, hydrogen, nitrogen (diatomic),

maleic anhydride.

and carbon dioxide. Gases are used for fundamental

Properties: Soluble in water and many organic sol-

research on the behavior of matter largely because

vents. Compatible with a wide range of gums, res-

the low concentration permits isolation of the phe-

ins, and plasticizers and with most metallic salts.

nomena far better than is possible in liquids or sol-

Stable in acid and alkaline solutions. Available in a

ids. A “perfect” or ideal gas closely conforms to the

range of molecular weights.

simple gas laws (Boyle’s law, Charles’ law) for

Use: Ammonium nitrate slurry explosives, for its

expansion and contraction. Note: Use of the word

suspending action and cross-linking ability; rust-

gas for gasoline, natural gas, or the anesthetic ni-

preventive films; antistatic and finishing agent in

trous oxide is acceptable only in informal communi-

natural and synthetic textiles and glass fibers; adhe-

cation.

sives and coatings; thickening agent and protective

See kinetic theory; compressed gas; noxious gas;

colloid; flocculant and foam stabilizer in papermak-

noble gas; vapor.

ing; photoreproduction; pharmaceutical prepara-

tions; cosmetics; etc.

gas, asphyxiant. See asphyxiant gas.

“Gantrez” M [International Specialty].

TM for polyvinyl methyl ether. gas black. See carbon black.

596GAS CHROMATOGRAPHY

gas chromatography. (GC; gas-liquid chro- hydrogen to form methane (hydrogasification); (2)

matography; GLC; vapor-phase chromatography; by reacting steam with hot coal (800C) in the pres-

VPC). The process in which the components of a ence of air or oxygen to form carbon monoxide and

hydrogen (synthesis gas), followed by a methana-

mix are separated from one another by volatilizing

tion reaction (Fischer-Tropsch method); (3) by un-

the sample into a carrier gas stream that is passing

derground aeration. In methods (1) and (2), the coal

through and over a bed of packing consisting of a

enters the reaction sequence in finely divided form;

20–200 mesh solid support. The surface of the latter

hydrocarbon gases, naphtha, and fuel oils of various

is usually coated with a relatively nonvolatile liquid

grades can be produced by several modifications. In

(the stationary phase). This gives rise to the term

method (3), air is pumped down to previously ignit-

gas-liquid chromatography. If the liquid is not

ed coal seams and the combustible products evolved

present, the process is gas-solid chromatography,

are collected. Many variations of methods (1) and

which is also widely used for analysis. Different

(2) have been researched in the U.S., but none is

components move through the bed of packing at

economically competitive with crude oil. Several

different rates and so appear separately, at the ef-

have advanced to the pilot stage, and projections of

fluent end, where they are detected and measured by

cost, investment, and installation for large-scale op-

thermal conductivity changes, density differences,

eration have been made. Environmental and geo-

or ionization detectors. Gas chromatography is ad-

graphic considerations have also been investigated.

vantageous as a means of analysis of minute quanti-

The controlling factor for future development is the

ties of complex mixtures from industrial, biological,

price of crude. All three methods mentioned are

and chemical sources and is also of potential value in

technically feasible. During World War II hydrocar-

actually preparing moderate quantities of highly pu-

bon fuels were produced from coal on a large scale in

rified compounds otherwise difficult to separate

Germany by both hydrogasification and Fischer-

from the mixture in which they occur.

Tropsch methods. Large-scale coal conversion has

been successfully achieved by the Lurgi and Sasol

gas, compressed. See compressed gas; lique-

methods; the latter, in South Africa, is a large-scale

fied petroleum gas.

installation utilizing the Fischer-Tropsch technolo-

gy. The Lurgi technique is in production at a number

gas constant (R). Pressure times volume divid-

of locations. Catalytic gasification of peat for pro-

ed by the temperature of one gram-molecule of any

duction of methanol is now utilized on a commercial

ideal gas in the general gas law.

scale; use of lignite and wood for this purpose is

under development.

273C

See Fischer-Tropsch process; synthesis gas.

gas, inert. See noble gas, inert.

gas constant, molar. R in general gas law, PV

nRT, equal to 0.082060 L-atm mole

−1

degree

−1

gas laws. See Boyle’s law; Charles’ law;

Gay-Lussac’s law; ideal gas.

gaseous diffusion. See diffusion, gaseous.

gas, liquefied petroleum. See liquefied pe-

gas hydrate. A clathrate compound formed by a

troleum gas.

gas (either noble or reactive) and water. The com-

pounds are crystalline solids and are insoluble in

gas liquid. See light hydrocarbon.

water. They usually form (only at relatively low

temperatures and high pressures) directly by contact

gas, natural. See natural gas.

of gas and liquid water. From 6 to 18 molecules of

water may combine with each molecule of gas, de-

gas, noble. See noble.

pending on the nature of the gas. The best-known

gas hydrates are those of ethane, ethylene, propane,

and isobutane. Others include methane and 1-bu-

gasohol Gasoline blended with alcohol. Typically

tene, most of the fluorocarbon refrigerant gases, 10% methanol or ethanol is blended with the gaso-

nitrous oxide, acetylene, vinyl chloride, carbon di- line.

oxide, methyl and ethyl chloride, methyl and ethyl

bromide, cyclopropane, hydrogen sulfide, methyl

gas oil. A liquid petroleum distillate with viscosi-

mercaptan, and sulfur dioxide. Interest in the gas

ty and boiling range between those of kerosene and

hydrates originated mainly because of the nuisance

lubricating oil. Boiling range 232–426C, flash p

of such compound formation in gas pipelines. In

150F (65.5C), autoign temp 640F (337C). Combus-

recent years, propane has been used successfully to

tible.

precipitate water from salt solution (or seawater),

Use: Absorption oil, manufacture of ethylene.

thus yielding potable water.

gasoline.

gasification.

Production of gaseous or liquid hy- CAS: 8006-61-9. A mixture of volatile hydrocar-

drocarbon fuels from coal (1) by direct addition of bons suitable for use in a spark-ignited internal-

597 GAUGE

combustion engine and having an octane number of other chemical conversion processes. Its octane

at least 60. The major components are branched- number is low.

chain paraffins, cycloparaffins, and aromatics. white gasoline. An unleaded gasoline especially de-

There are several methods of production: distillation signed for use in motorboats; it is uncracked and

or fractionation, which yields straight-run product strongly inhibited against oxidation to avoid gum

formation and is usually not colored to distinguish it

of relatively low octane number, used primarily for

from other grades. It also serves as a fuel for camp

blending; thermal and catalytic cracking; reforming;

lanterns and portable stoves.

polymerization; isomerization; and dehydrocyclo-

Hazard: Highly flammable, dangerous fire and ex-

dimerization. All but the first are various means of

plosion risk. TLV: 300 ppm; STEL 500 ppm; animal

converting hydrocarbon gases into motor fuels by

carcinogen.

modifications of chemical structure, usually involv-

ing catalysis. The present commercial source of gas-

gas, perfect. See ideal gas.

oline is petroleum, but it may also be produced from

shale oil and Athabasca tar sands, as well as by

Gastaldi synthesis. Formation of dicyanopyra-

hydrogenation or gasification of coal.

zines by cyclization of two molecules of an amino-

anti-knock gasoline. A gasoline to which a low per-

cyanomethyl ketone, produced by treatment of an

centage of methyl-tert-butyl ether (MBTE) has been

isonitrosomethyl ketone bisulfite compound with

added to eliminate knocking and increase octane

potassium cyanide, heating in hydrochloric acid,

number. This compound has almost completely re-

and oxidation.

placed tetraethyllead. Gasolines of octane number

100 or more are used chiefly as aviation fuel; those

gastric juice. A mixture of hydrochloric acid

having a research octane number of approximately

and pepsin secreted by glands in the stomach in

90 are in general automotive use. See antiknock

response to a conditioned nerve reflex. Its pH is

agent; octane number.

about 2.0. Its action in the metabolic breakdown of

casinghead gasoline. See natural gasoline (below).

food components is essential to the digestive pro-

cracked gasoline. Gasolines produced by the cata-

cess, though carbohydrate decomposition is initiat-

lytic decomposition of high-boiling components of

ed by the saliva.

petroleum. In general, such gasolines have much

See digestion (1).

higher octane ratings (80–100) than that produced

by fractional distillation. The difference is due to the

gastrin tetrapeptide amide.

prevalence of unsaturated, aromatic, and branched-

CAS: 1947-37-1. mf: C

chain hydrocarbons in the cracked gasoline. The

Hazard: Moderately toxic by ingestion.

actual properties vary widely with the nature of the

starting material and the temperature, time, pres-

gate. The opening in an injection mold leading

sure, and catalyst used in cracking.

from the sprue or runner to the mold cavity; the term

high-octane gasoline. A gasoline with an octane

also refers to molded material removed from the

number of 90–100. See antiknock gasoline;

aperture when the product is ejected.

octane number.

lead-free gasoline. An automotive fuel containing

Gattermann aldehyde synthesis. Prepara-

no more than 0.05 g lead per gallon, designed for use

tion of aldehydes of phenols, phenol ethers, or het-

in engines equipped with catalytic converters.

erocyclic compounds by treatment of the aromatic

natural gasoline. A gasoline obtained by recovering

substrate with hydrogen cyanide and hydrochloric

the butane, pentane, and hexane hydrocarbons

acid in the presence of Lewis acid catalysts.

present in small proportion in certain natural gases.

Used in blending to produce a finished gasoline with

Gattermann-Koch reaction. Formulation of

adjusted volatility but low octane number. Do not

benzene, alkylbenzenes, or polycyclic aromatic hy-

confuse with natural gas.

drocarbons with carbon monoxide and hydrochloric

polymer gasoline. A gasoline produced by polymer-

acid in the presence of aluminum chloride at high

ization of low molecular weight hydrocarbons such

pressure. Addition of cuprous chloride allows the

as ethylene, propene, and butenes. Used in small

reaction to proceed at atmospheric pressure.

amounts for blending with other gasolines to im-

prove their octane numbers.

pyrolysis gasoline. Gasoline produced by thermal

gauge. An instrument for measuring and indicat-

cracking as a by-product of ethylene manufacture. It ing such process variables as pressure (hydraulic,

is used as a source of benzene by the hydrodealkyla- steam, air), liquid level, thickness, vacuum, etc. The

tion process. many types of gauges are activated by mechanical,

reformed gasoline. A high-octane gasoline obtained ultrasonic, electronic, magnetic, and pneumatic

from low-octane gasoline by heating the vapors to a means. Some operate on the principle of automatic

high temperature or by passing the vapors through a control. In materials technology, the term gauge is

suitable catalyst. often synonymous with thickness, especially in the

straight-run gasoline. Gasoline produced from pe- metals, rubber, and plastics fields. Light gauge re-

troleum by distillation without use of cracking or fers to thicknesses from about 0.005 to 0.05 inch,

598GAY-LUSSAC, JOSEPH LOUIS

and heavy gauge to thicknesses from about 0.05 to tain much solvent in the interstices (so-called

0.150 inch. “brush-heap” structure). Gels are usually transpar-

See mil; meter (2). ent but may become opalescent.

See pectin.

Gay-Lussac, Joseph Louis. (1778–1850). A

French chemist and physicist noted for the brilliance

gelatin. A mixture of proteins obtained by hydrol-

and accuracy of his reasoning and experimental ysis of collagen by boiling skin, ligaments, tendons,

etc. Its production differs from that of animal glue in

work. He contributed greatly to the knowledge of

that the raw materials are selected, cleaned, and

gases in his discovery (1808) of the law of combin-

treated with special care so that the product is clean-

ing volumes and his independent discovery (1802)

er and purer than glue. Type A gelatin is obtained

of the law of Charles, the relationship of temperature

from acid-treated raw materials, and type B from

to the volume of gases. He graduated from and

alkali-treated raw materials. Gelatin is strongly hy-

taught at the Ecole Polytechnique, becoming a full

drophilic, absorbing up to 10 times its weight of

professor in 1810. His work in chemistry was exten-

water and forming reversible gels of high strength

sive, resulting in the discovery of boron, which he

and viscosity. It can be chemically modified to make

named, with Louis-Jacques Thenard, and a variety

it insoluble in water for such special applications as

of compounds such as boron trifluoride, chloric

microencapsulation of fish nutrients for fish culture.

acid, and dithionic acid (H

). He identified io-

Properties: Flakes or powder; odorless; tasteless.

dine as an element, named it, and studied its proper-

Soluble in warm water and glycerol; insoluble in

ties. He investigated the relationship of acids and

organic solvents.

bases and introduced many analytical techniques

Grade: Edible, photographic, technical, USP.

(such as the use of litmus as an indicator). Among

Use: Photographic film; sizing; textile and paper ad-

his many contributions to industrial chemistry were

hesives; cements; capsules for medicinals; matches;

improvements in the production of sulfuric acid.

light filters; clarifying agent; desserts, jellies, etc.;

Much of the progress of chemistry in the early 19th

culture medium for bacteria; blood plasma volume

century is associated with his career.

expander; microencapsulation; printing inks; nutri-

ent; protective colloid in ice cream.

Gay-Lussac’s law. A modification of Charles’

law to state the following: At constant pressure the

gelatin dynamite. A high explosive that con-

volume of a confined gas is proportional to its abso-

tains nitrocellulose in addition to nitroglycerin. The

lute temperature. The volumes of gases involved in a

product is a gelatinized mass, less sensitive to shock

chemical change can always be represented by the

and friction than straight dynamite.

ratio of small whole numbers.

gel electrophoresis. A procedure for separat-

GC. Abbreviation for gas chromatography.

ing a mixture of molecules through a stationary

material (gel) in an electrical field.

GC-rich area. Many DNA sequences carry

long stretches of repeated G and C, which often

gel filtration. A type of fractionation procedure

indicate a gene-rich region.

in which molecules are separated from each other

according to differences in size and shape; the action

Gd. Symbol for gadolinium.

is similar to that of molecular sieves. Dextran gels

(three-dimensional networks of polysaccharide

GDME. Abbreviation for glycol dimethyl ether.

chains) are usually used in this method known as

See ethylene glycol dimethyl ether.

gel-filtration chromatography.

See fractionation; molecular sieve.

GDNF. Abbreviation for glial cell line-derived

neurotrophic factor.

“Gelflex Blue” [ACC Silicones]. TM for a

reusable moulding rubber.

GDP. Abbreviation for guanosine diphosphate.

See guanosine phosphates.

“Gelgard” [Dow]. TM for a synthetic polymer-

ic water-gelling material.

GDUE. See 1h,3h,5h-oxazolo(3,4-c)oxazole-

Use: Fire control.

7a(7h)-methanol.

gelled hydrogen. Liquid hydrogen thickened

Ge. Symbol for germanium.

with silica powder.

Use: Rocket fuel.

gel. A colloid in which the disperse phase has

combined with the continuous phase to produce a

viscous jellylike product. Only 2% gelatin in water

gel paint. (thixotropic paint). A paint formula-

forms a stiff gel. A gel is made by cooling a solution, tion that has a semisolid or gel consistency when

whereupon certain kinds of solutes (gelatin) form undisturbed, but that flows readily under the brush

submicroscopic crystalline particle groups that re- or when stirred or shaken. After removal of the

599 GENE TESTING

stress, it becomes stiff again and has little tendency nism in which it functioned in the same manner as

to spill, drip, or run. The thixotropic quality is ob- would a normal gene. Because of the ability of DNA

to store and transfer coded genetic instructions,

tained by the carefully controlled reaction of a rela-

genes determine the sequence of amino acids in

tively small proportion of a polyamide resin with an

specific polypeptides (see proteins), thus they pre-

alkyd resin vehicle.

scribe the structure of the proteins synthesized. In

See thixotropy.

viruses, the genes consist of ribonucleic acid (RNA).

Mutation of genes is a change in the basic sequence

gel-permeation chromatography. (GPC).

of amino acids in DNA and may be induced by

The form of liquid chromatography that sorts poly-

ionizing radiation. Mutations can occur in any living

mer molecules in a gel-packed column according to

cell. See genetic code; radiation, ionizing;

their size in solution.

recombinant DNA; molecular biology.

gelsemine.

CAS: 509-15-9. C

gene amplification. Any process by which spe-

Hazard: A toxic plant alkaloid.

cific DNA sequences are replicated disproportion-

Use: Medicine, as a CNS stimulant.

ately larger than their representation in the parent

molecules; during development, some genes be-

gel shift assay. (gel mobility shift assay

come amplified in specific tissues.

(GMSA); band shift assay (BSA); electropho-

See gene; oncogene.

retic mobility shift assay (EMSA). A method by

which one can determine whether a particular pro-

gene chip technology. Development of

tein preparation contains factors which bind to a

cDNA microarrays from a large number of genes.

particular DNA fragment. When a radiolabeled

Used to monitor and measure changes in gene ex-

DNA fragment is run on a gel, it shows a characteris-

pression for each gene represented on the chip.

tic mobility. If it is first incubated with a cellular

extract of proteins (or with purified protein), any

gene deletion. The total loss or absence of a

protein-DNA complexes will migrate slower than

gene.

the naked DNA—a shifted band.a

gene expression. The process by which a

“Gelva” [Solutia]. TM for a family of acrylic

gene’s coded information is translated into the struc-

multipolymer products designed for high-perfor-

tures present and operating in the cell (either pro-

mance, pressure-sensitive adhesive applications

teins or RNAs).

where skin adhesion, high temperature and/or diffi-

cult-to-adhere-to surface are involved. Provided for

gene families. Groups of closely related genes

both solvent and water based grades.

that make similar products.

Use: Medical, automotive, solar film, graphics, and

specialty tape products.

gene library. See genomic library.

gem-. Prefix. Abbreviation of geminate, meaning

two identical groups attached to the same carbon

gene mapping. Determination of the relative

atom.

positions of genes on a DNA molecule (chromo-

some or plasmid) and of the distance, in linkage

gemicitabine.

units or physical units, between them.

CAS: 95058-81-4. mf: C

Hazard: Human systemic effects

gene pool. All the variations of genes in a spe-

cies.

gene. A complex of nucleoproteins (chiefly DNA)

See allele; gene; polymorphism.

that is the active transmitter of genetic information.

Each of the body’s 50,000 to 100,000 genes contains

gene prediction. Predictions of possible genes

the code for a specific product, typically, a protein

made by a computer program based on how well a

such as an enzyme.

stretch of DNA sequence matches known gene se-

Genes occur on the chromosomes of every living

quences

cell, where they are arranged in a linear order. Ge-

netic mechanism is the same in all organisms, rang-

gene product. The biochemical material, either

ing from the lowest forms of life, both plant and

RNA or protein, resulting from expression of a gene.

animal, to humans. Every organism has a large num-

The amount of gene product is used to measure how

ber of different genes; there are over 10,000 in each

active a gene is; abnormal amounts can be correlated

cell of the human body. These control the intricate

with disease-causing alleles.

and well-balanced system of biochemical reactions

in the cell. The first synthesis of a gene was reported

in 1970. In 1976, it was announced that a synthetic

gene testing. See genetic testing; genetic

gene was successfully introduced into a microorga- screening.

600GENE THERAPY

gene therapy. An experimental procedure organ, etc.).

aimed at replacing, manipulating, or supplementing See protein; amino acid; ribonuclease.

nonfunctional or misfunctioning genes with healthy

genes.

genetic counseling. Provides patients and their

See gene; inherit; somatic cell gene therapy; germ

families with education and information about ge-

line gene therapy.

netic-related conditions and helps them make in-

formed decisions.

gene transfer. Incorporation of new DNA into

and organism’s cells, usually by a vector such as a

genetic discrimination. Prejudice against

modified virus. Used in gene therapy.

those who have or are likely to develop an inherited

See mutation; gene therapy; vector.

disorder.

general acid-base catalysis. Catalysis in-

volving a proton transfer from/to a molecule other

genetic engineering. Transference of genetic

than water. Compare to specific acid-base catalysis.

material from the genes of one species to those of

another by uniting a portion of the DNA of one

organism with extranuclear sections of DNA from

generic formula. See formula, chemical.

another organism (also called gene-splicing). Such

recombinant molecules will replicate in the same

“Genesolv” [General Electric]. TM for ul-

way as in normal DNA behavior. This technique is

trapure halogenated hydrocarbon solvents of the

being utilized in basic genetic research sponsored by

methane and ethane series.

the National Institutes of Health.

Properties: High densities and low viscosities, com-

There have been a number of outstanding achieve-

bined residue (soluble plus insoluble matter) is less

ments in genetic engineering in which bacteria are

than 1 ppm.

made to form chains of amino acids programmed by

Grade: Standard and electronic, Genesolv D, 200,

nucleic acids supplied by the experimenters; (1)

and 2004.

Production of human insulin from E. coli by im-

Hazard: Nonflammable, nonexplosive, thermally

planting synthetic genes in the bacterium; commer-

stable, and relatively nonhydrolyzable.

cial production of such synthetic insulin has been

Use: Removal of greases and oils from metal, plastic,

going on for some time, and the product has been

elastomer, and paint or varnish surfaces. Used with

approved by the FDA. (2) Formation and secretion

all cleaning techniques on assembled motors and

by E. coli of the protein ovalbumin. (3) Synthesis of

parts, electronic devices, precision components,

rat growth hormone in bacteria. (4) Synthesis of

motion-picture film, refrigeration systems, etc. Also

human growth hormone in bacteria; it will probably

used for isolation of viruses, for fire extinguishing,

be developed on a commercial scale. (5) Production

and as dielectric coolants.

of a biologically active protein closely similar to

interferon by exposing to the action of viruses bacte-

gene-splicing. The enzymatic attachment of one

ria that have been programmed to form it by intro-

exon to another.

duction of the appropriate genetic code. (6) Creation

See genetic engineering.

of a wholly synthetic bacterium characterized by

unusual ability to consume crude oil.

gene testing. Examining a sample of blood or

Various patents are pending on some of these tech-

other body fluid or tissue for biochemical, chromo-

niques for commercial exploitation. The Supreme

somal, or genetic markers that indicate the presence

Court has ruled that these and other results of genetic

or absence of genetic disease.

engineering are patentable inventions. See bio-

technology.

gene therapy. Treatment that alters genes (the

basic units of heredity found in all cells in the body).

genetic engineering technology. See re-

In early studies of gene therapy for cancer, research-

combinant DNA technology.

ers are trying to improve the body’s natural ability to

fight the disease or to make the tumor more sensitive

to other kinds of therapy.

genetic illness. Sickness, physical disability, or

other disorder resulting from the inheritance of one

genetic code. Information stored in the genes

or more deleterious alleles.

that program the linear sequence of amino acids

within the protein polypeptide chain synthesized

genetic information. The hereditary informa-

during cell development. The agencies involved are

tion contained in a sequence of nucleotide bases.

DNA (deoxyribonucleic acid) and RNA (ribonucle-

ic acid). It is this information code (analogous to a

computer language) that determines (1) the nature

genetic linkage map. A chromosome map

and type of an organism, i.e., its heredity, and (2) the showing the relative positions of the known genes

kind of cell structure to be formed (muscle, bone, on the chromosomes of a given species.

601 GENOME

genetic map. A diagram showing the position of

specific genes along a chromosome relative to

markers.

Branched compounds are so named to show the proper

genetic marker A gene or other identifiable

deviation, e.g., 2-methyl propane

portion of DNA whose inheritance can be followed.

See chromosome; DNA; gene; inherit.

genetic material. See genome

is a derivation of propane, not of methane. Similarly,

isopentane

genetic mosaic. An organism in which different

cells contain different genetic sequence. This can be

the result of a mutation during development or fu-

sion of embryos at an early developmental stage.

genetic polymorphism. Difference in DNA

is named 2-methylbutane. The four carbons in a

sequence among individuals, groups, or populations

straight line give the name butane, and the side group

(e.g., genes for blue eyes versus brown eyes).

is attached to the second carbon. Another pentane has

the structure

genetic predisposition. Susceptibility to a ge-

netic disease. May or may not result in actual devel-

opment of the disease.

and was once called tetramethyl pentane. Under the

genetics. The scientific study of heredity—how

Geneva System, it is named in terms of two methyl

particular qualities or traits are transmitted from

groups joined to carbon number two in a propane chain

parents to offspring.

(e.g., 2,2-dimethyl propane). Some special recommen-

dations of the Geneva System define the use of certain

genetic screening. Testing groups of individu-

suffixes: open-chain hydrocarbons with one double

als to identify defective genes capable of causing

bond end in -ene; those with two double bonds end in -

hereditary conditions.

diene (alkenes and alkadienes rather than olefins and

diolefins). Triple-bonded compounds end in -yne. Al-

genetic testing. Analyzing an individual’s ge-

cohols are named by use of the hydrocarbon name with

netic material to determine predisposition to a par-

-ol as the characteristic suffix, i.e., methanol, ethanol,

ticular health condition or to confirm a diagnosis of

etc. In order to extend this plan to polyhydric alcohols,

genetic disease.

a syllable such as di-, tri-,ortetra- is inserted between

the name of the parent hydrocarbon and the suffix -ol.

genetic variation. A phenotypic variance of a

trait in a population attributed to genetic hetero-

geneity.

“Genetron” [General Electric]. TM for a

Sulfides, disulfides, sulfoxides, and sulfones are

group of fluorinated hydrocarbons of the methane

named like ethers, the oxy term being replaced with

and ethane series.

thio-, dithio-, sulfinyl, and sulfonyl. The acids are also

Properties: Low moisture content, noncorrosive,

named in accordance with the Geneva System.

nonflammable, stable, low power requirement per

See chemical nomenclature.

unit of refrigeration, high dielectric strength.

Use: Refrigerant and foam expansion agent.

genin. The steroid portion linked to a sugar resi-

due in certain glycosides. Important genins are

found in the digitalis glycosides used as heart stimu-

Geneva System. A system of nomenclature for

lants.

organic compounds recommended in 1892. It is

based on compounds derived from hydrocarbons as

a starting point, the names corresponding to the

genome. The total DNA contained in each cell of

longest straight carbon chain present. The position is an organism. Mammalian genomic DNA (including

indicated by numbers applied to the carbons of the that of humans) contains 6x109 base pairs of DNA

straight chain, beginning with the end carbon near- per diploid cell. There are somewhere in the order of

est the substituent element or group. Normal com- a hundred thousand genes, including coding re-

pounds, in which the carbons are linked in a straight gions, 5

′

and 3

′

untranslated regions, introns, 5

′

and

chain, are named ethane, propane, pentane, etc. Nor- 3

′

flanking DNA. Also present in the genome are

mal propane is structural segments, such as telomeric and centro-

602GENOME MAPS

meric DNAs and replication origins, and intergenic ter, alcohol, and ether; insoluble in carbon disulfide,

DNA. chloroform, and benzene.

Use: Medicine, as sodium gentisate (analgesic).

genome maps. Charts that indicate the ordered

arrangement of the genes or other DNA markers

geochemistry. The study of the chemical com-

within the chromosomes.

position of the earth in terms of the physicochemical

and geological processes and principles that pro-

genome project. Research and technology-de-

duce and modify minerals and rocks. Of practical

velopment effort aimed at mapping and sequencing

importance in discovering and establishing the lim-

the genome of human beings and certain model

its of ore deposits, petroleum, tar sands, salt, sulfur,

organisms.

and other valuable resources.

See Human Genome Initiative.

geometric isomer. A type of stereoisomer in

genomic blot. A type of Southern blot specifi-

which a chemical group or atom occupies different

cally used to analyze a mixture of DNA fragments

spatial positions in relation to the double bonds. If

derived from total genomic DNA. Because genomic

the double bond is between two carbon atoms, the

DNA is very complicated, when it has been digested

isomers are called cis and trans, as in crotonic acid,

with restriction enzymes it produces a complex set

where the H and COOH reverse locations:

of fragments ranging from tens of bp to tens of

thousands of bp. However, any specific gene will be

reproducibly found on only one or a few specific

fragments. A million identical cells will produce a

million identical restriction fragments for any given

gene, so probing a genomic Southern with a gene-

If the double bond is between a nitrogen and a carbon

specific probe will produce a pattern of perhaps one

atom, the isomers are named anti and syn, as in benzal-

or just a few bands.

doxime, where the OH group shifts locations.

genomic clone. A piece of DNA taken from the

genome of a cell or animal, and spliced into a bacter-

iophage or other cloning vector. A genomic clone

may contain coding regions, exons, introns, 5

′

flank-

This phenomenon also occurs in saturated ring com-

ing regions, 5

′

untranslated regions, 3

′

flanking re-

pounds having three or more members in the ring, as

gions, 3

′

untranslated regions, or it may contain none

well as in certain coordination compounds.

of these.

See stereochemistry.

genomic library. A collection of clones made

“Geon” [B. F. Goodrich].

from a set of randomly generated overlapping DNA

CAS: 9002-86-2. TM for polyvinyl chloride formu-

fragments representing the entire genome of an or-

lated for moldings, extrusions, binders, and

ganism.

coatings.

Use: For appliance applications, electronic parts,

genomics. The study of genes and their function.

medical devices, construction applications, bottles,

wiring, and cable.

genomic sequence. See DNA.

genotype. The genetic constitution of an organ-

geothermal energy. Superheated water and

ism, as distinguished from its physical appearance

steam trapped in rock strata in areas characterized by

(its phenotype).

volcanic activity or by intrusions of molten magma.

Associated temperatures range from 150 to 300C. It

gentamicin. (gentamycin).

escapes either from natural surface vents (geysers,

CAS: 1403-66-3. C

fumaroles, hot springs) or from bore holes drilled

Properties: Amorphous solid. Mp 102–108C. Freely

through the strata. A contributing source of heat is

soluble in water, pyridine, acid solutions; moderate-

the natural radioactivity of rocks in the earth’s upper

ly soluble in methanol, ethanol, and acetone; practi-

mantle. Power was produced in Italy from geother-

cally insoluble in benzene and halogenated hydro-

mal sources as long ago as 1913; since then geother-

carbons.

mal power plants have been installed in Iceland,

Use: Antibacterial.

New Zealand, France, Hungary, Japan, Mexico, and

El Salvador. Many nonelectrical uses have been

gentian violet. USP name for methyl violet.

developed for home heating and industrial purposes,

especially in Iceland. The chief source of geother-

gentisic acid. (2,5-dihydroxybenzoic acid). mal energy in the continental U.S. is the California-

CAS: 490-79-9. C

(OH)

COOH. Nevada area. The geysers in central California have

Properties: Crystals. Mp 199–200C. Soluble in wa- been generating electric power from steam in sub-

603 GERMANIUM DIOXIDE

stantial amounts for some years. The same is true of (20C). Soluble in most oils; insoluble in glycerol.

Hawaii. Geological formations appropriate for geo- Combustible.

thermal heat are so few that this form of energy will Use: Perfumery, flavoring.

always have limited potential.

germacrone.

geranial. See citral.

CAS: 6902-91-6. mf: C

Hazard: A poison by ingestion.

geranialdehyde. See citral.

“Germall” [Isp Europe]. TM for a broad

geraniol. (trans-3,7-diemthyl-2,6-octadien-1-

spectrum highly effective preservative.

ol). (CH

)

C:CH(CH

)

C(CH

):CHCH

OH. A ter-

pene alcohol.

“Germall 115” [Sutton].

Properties: Colorless to pale-yellow, liquid oil;

CAS: 39236-46-9. TM for imidazolidinyl urea.

pleasant geranium-like odor. D 0.870–0.890 (15C),

Use: Preservative in cosmetics.

fp −15C, bp 230C, refr index 1.4710–1.4780 (20C),

optical rotation −2 to +2 degrees. Soluble in alcohol,

germane. A germanium hydride of the general

ether, mineral oil, fixed oils; insoluble in water and

formula Ge

2n+2

glycerol. Combustible.

See germanium tetrahydride.

Derivation: From citronella oil (Java), citronellol-

free grades from palmerosa oil, and (synthetically)

germanium. Ge. Nonmetallic element of atomic

from pinene. These are of higher quality.

number 32, aw 72.59, valences of 2, 4; group IVa of

Grade: Standard, soap, synthetic, FCC, EOA.

the periodic table.

Use: Perfumery, constituent of synthetic fragrances

Properties: Grayish-white solid. A p-type semicon-

and synthetic linalool.

ductor, conductivity depends largely on added im-

purities, d 5.323, mp 937.4C, bp 2830C, oxidizes

geranyl acetate. (geraniol acetate).

readily at 600–700C, does not volatilize to approxi-

CAS: 105-87-3. CH

COOC

mately 1350C, Mohs hardness 6. Attacked by nitric

Properties: Clear, colorless liquid; odor of lavender.

acid and aqua regia; stable to water, acids, and alka-

D 0.907–0.918 (15C), bp 242C, optical rotation −2

lies in the absence of dissolved oxygen.

to +2 degrees, refr index 1.4580–1.4640 (20C). Sol-

Derivation: Recovered from residues from refining

uble in alcohol and ether; insoluble in water and

of zinc and other sources, by heating in the presence

glycerol. Combustible.

of air and chlorine. It is also present in some coals

Derivation: (1) Constituent of several essential oils.

and can be recovered from their ash.

(2) By heating geraniol and sodium acetate with

Occurrence: Missouri, Kansas, Oklahoma.

acetic anhydride.

Method of purification: The chloride is distilled and

Grade: Technical, FCC.

then hydrolyzed to the oxide, which is reduced by

Use: Perfumery, flavoring.

hydrogen to the metal. Zone melting is used for final

purification. Single crystals are made by vaporiza-

geranyl butyrate. (geraniol butyrate).

tion of germanium diiodide. The impurities in ger-

COOC

manium are of controlling importance in its use in

Properties: Colorless liquid; roselike odor. Bp 151C

transistors. These are added to high-purity germani-

(18 mm Hg), d 0.9008 (17/4C). Insoluble in water

um in trace amounts during growth of single

and glycerol; soluble in alcohol, ether. Occurs in

crystals.

several essential oils. Combustible.

Grade: Transistor, i.e., impurities 1 part in 10

Grade: FCC.

Available forms: Ingots, single crystals, pure or

Use: Perfumes and soaps, flavoring, synthetic attar of

doped, powder.

rose.

Use: Solid-state electronic devices (transistors,

diodes), semiconducting applications, brazing al-

geranyl formate. (geraniol formate).

loys, phosphors, gold and beryllium alloys, infrared-

CAS: 105-86-2. HCOOC

transmitting glass.

Properties: Colorless liquid. Bp 113 (15 mm Hg), d

0.927 (20/4C), roselike odor. Insoluble in alcohol

germanium dichloride. GeCl

. White powder,

and ether. Occurs in several essential oils. Combus-

mp (decomposes), decomposes in water, soluble in

tible.

germanium tetrachloride, insoluble in alcohol and

Grade: FCC.

chloroform.

Use: Perfumes and soaps, flavoring, synthetic neroli

oil.

germanium dioxide. (germanium oxide).

geranyl propionate. (geraniol propionate). CAS: 1310-53-8. GeO

COOC

. Properties: White powder, hexagonal, tetragonal,

Properties: Colorless liquid; roselike odor. D and amorphous.

0.896–0.913 (25C), refr index 1.4570–1.4650 Grade: Technical, semiconductor, 99.999% pure.

604GERMANIUM MONOXIDE

Use: Phosphors, transistors and diodes, infrared- disease.

transmitting glass. See genomics; somatic cell gene therapy.

germanium monoxide. GeO.

germ line genetic mutation. See mutation.

Properties: Black solid. Mp 710C (sublimes); insol-

uble in water; soluble in oxidizing agents. Available

commercially 99.999% pure.

getter. See scavenger.

germanium potassium fluoride. (potassi-

um germanium fluoride). K

GeF

ghatti gum. Exudation from the stem of Ano-

Properties: White crystals. Soluble in water (hot);

geissus latifolia.

insoluble in alcohol.

Properties: Colorless to pale-yellow tears, rounded

Grade: Technical.

or vermiform. Almost tasteless and odorless, par-

Hazard: Toxic material. TLV: 2.5 mg(F)/m

tially soluble in water. Can be solubilized by auto-

claving.

germanium telluride. GeTe.

Use: Thickener and protective colloid; emulsifier for

Properties: An efficient semiconductor. Mp 725C.

oils, fats, waxes.

germanium tetrachloride.

CAS: 10038-98-9. GeCl

“Ghost Remover” [Ulano]. TM for an ink

Properties: Colorless liquid. D 1.874 (25/25C), fp

haze and stencil residue remover.

−49.5C (1 atm), bp 83.1C, refr index 1.464, decom-

Use: Effective on most inks and emulsions.

poses in water. Insoluble in concentrated hydrochlo-

ric acid; soluble in carbon disulfide, chloroform,

benzene, alcohol, and ether.

Giauque, William F. (1895–1982). An Amer-

Derivation: Reaction of chlorine with elemental ger-

ican chemist who achieved distinction for his studies

manium.

of the properties of matter at temperatures approach-

ing absolute zero (−273C). This research established

germanium tetrahydride.

the science of cryogenics. Giauque received the No-

CAS: 7782-65-2. GeH

bel Prize in chemistry in 1949. He was professor and

Properties: Colorless gas, d 3.43 g/L, fp −165C, bp

research director at the University of California at

−88C, decomposes at 350C, insoluble in water, sol-

Berkeley. One of his most significant contributions

uble in liquid ammonia, slightly soluble in hot hy-

was the invention of a magnetic cooling device that

drochloric acid.

made it possible to attain cryogenic temperatures.

Hazard: Toxic material. TLV: 0.2 ppm.

An important property of matter discovered as a

result of his work is superconductivity.

germ cell. The reproductive cells, either egg or

See cryogenics; superconductivity.

sperm cells. Germ cells are haploid and have only

one set of chromosomes (23 in all), while all other

cells have two copies (46 in all).

gibberellic acid.

CAS: 77-06-5. C

. A plant-growth-promoting

germicide. See bactericide.

hormone. It is a tetracyclic dihydroxylaectonic acid.

It was synthesized in 1978.

germ line. The continuation of a set of genetic

Properties: Crystals. Mp 233–235C. Slightly solu-

information from one generation to the next.

ble in water; soluble in methanol, ethanol, acetone;

See inherit.

soluble in aqueous solutions of sodium bicarbonate

and sodium acetate.

germination. The process by which a seedling

Use: Agriculture and horticulture, malting of barley

emerges and develops from a seed, or by which a

with improved enzymatic characteristics.

sporeling emerges and develops from a spore.

germ-line cell. A class of animal cells formed

gibberellin. A group of plant-growth regulators

early in embryogenesis that are set aside for repro-

(hormones), isolated in 1938 and widely distributed

ductive function (give rise to gametes). All other

in flowering plants that promotes elongation of

cells are somatic cells.

shoots and coleoptiles. They differ from auxins in

not stimulating the growth of roots and in various

germ line gene therapy. An experimental other properties. The presence of auxin appears to be

process of inserting genes into germ cells or ferti- necessary for gibberellins to function. All gibberel-

lized eggs to cause a genetic change that can be lins have closely related structures, being weak

passed on to offspring. acids with a ring system containing double bonds

Use: To alleviate effects associated with a genetic and eight asymmetric carbons.

605 “GLACIER”

metallurgical coke.

See asphalt; bitumen.

gin. An alcoholic beverage made by distilling al-

cohol through a mixture of herbs and berries (juni-

per, coriander, etc.) and adjusting to 80–100 proof.

Properties: Flash p 90F (32.3C).

Hazard: Flammable, moderate fire risk. Slight irri-

tant, intoxicant.

See gibberellic acid; plant-growth regulator.

ginkgo biloba l., root extract.

Gibbs-Duhem equation. (GDE). An exact

CAS: 90045-36-6.

thermodynamic relation that permits computation of

Hazard: Low toxicity by ingestion. Human systemic

the changes of chemical potential for one compo-

effects.

nent of a uniform mixture over a range of composi-

Source: Natural product.

tions, provided the changes of potential for each of

the other components have been measured over the

ginsenoside.

same range.

CAS: 74749-74-9.

Hazard: A poison.

Gibbs, Josiah Willard. (1839–1903). The fa-

Source: Natural product.

ther of modern thermodynamics. During his lifelong

post as professor of mathematical physics at Yale,

Girard’s reagent. (Girard’s “P”: carboxyme-

he stated the fundamental concepts embraced by the

thylpyridinium chloride hydrazide; acethydrazi-

three laws of thermodynamics, especially the nature

depyridinium chloride). C

NClCH

CONHNH

of entropy. A theorist rather than an experimenter,

(Girard’s “T”: carboxymethyltrimethyl ammo-

Gibbs was the first to expound with mathematical

nium chloride hydrazide; trimethylacethydrazide

rigor the “relation between chemical, electrical, and

ammonium chloride). (CH

)

NClCH

CONHNH

thermal energy and capacity for work.” It has been

Properties: White to faintly pinkish crystals; little or

said that throughout his adult life Gibbs did nothing

no odor. Mp 190–200C. Soluble in water; insoluble

but think. The results established him as a great

in oils. T is hygroscopic.

creative scientist.

Use: Separation of aldehydes and ketones from natu-

See thermodynamics.

ral oily or fatty materials; extraction of hormones.

Gibb’s free energy. See free energy.

Girbotol absorption. (amine absorption). A

process for the removal of hydrogen sulfide or car-

Gibbs phase rule. See phase rule.

bon dioxide from a gaseous mixture. An organic

amine (ethanolamine or diethanolamine, which are

Gibbs phthalic anhydride process. Oxida-

basic) is allowed to flow down a tortuous path

tion of naphthalene to phthalic anhydride with air at

through a tower where it is contacted by and absorbs

360C over vanadium pentoxide and other catalysts.

(acidic) hydrogen sulfide or carbon dioxide from the

gas to be purified as it moves up the tower. The

giga-. Prefix meaning 10

units (symbol

G). 1 Gg

amine, contaminated with these products, is then

1 gigagram

grams.

sent from the bottom of the tower to a steam stripper

where it flows countercurrent to steam, which strips

Gilbert, Walter. (1932– ). An American mo-

the hydrogen sulfide or carbon dioxide from it. The

lecular biochemist who won the Nobel Prize for

amine is then returned to the top of the tower. The

chemistry in 1980 along with Berg and Sanger for

process is widely used in the petroleum industry for

their studies of the chemical structure of nucleic

purifying refinery and natural gases and for recovery

acid. Author of many papers on theoretical physics

of hydrogen sulfide for sulfur manufacture. Remov-

and molecular biology. He has been at Harvard since

al of carbon dioxide from gases is usually done with

1972.

monoethanolamine.

gilsonite. An asphaltic material or solidified hy-

glacial. A term applied to a number of acids, e.g.,

drocarbon found only in Utah and Colorado. One of

acetic and phosphoric, that have a freezing point

the purest (9.9%) natural bitumens. Said to be the

slightly below room temperature when in a highly

first solid hydrocarbon to be converted to gasoline.

pure state. For example, glacial acetic acid is 99.8%

Hazard: Irritant, skin sensitizer.

pure and crystallizes at 16.6C.

Use: Acid, alkali, and waterproof coatings; black

varnishes, lacquers, baking enamels, and japans;

wire-insulation compounds; linoleum and floor tile;

“Glacier” [Solutia]. TM for a new class of

paving; insulation; diluent in low-grade rubber com- metal-working fluids. It is biodegradable and non-

pounds; possible source of gasoline, fuel oil, and toxic, and generates no oil mist while in use. Pro-

606GLANCE

vides low maintenance, environmental compatiblil- deep-sea floats, potting compounds, and other com-

ity, and worker safety in metal operations. posites.

Use: Desirable when aggressive metal removal and

extreme requirements are desired. For grinding,

glass, borosilicate. See glass, heat-resistant.

milling, and turning in automotive, aviation, tool-

ing, and bearings.

glass ceramic. A devitrified or crystallized form

of glass whose properties can be made to vary over a

glance. A mineralogical term meaning brilliant or wide range.

lustrous; used to describe hard, brittle materials that Properties: Rupture modulus up to 50,000 psi, d 2.5,

exhibit a bright reflecting surface when fractured. thermal shock resistance 900C, highest continuous-

Examples of such materials are hard asphalts use temperature 700C. Glass ceramics lie between

(glance pitch) and ores of certain metals such as lead borosilicate glasses and fused silica in high-temper-

glance (galena). ature capability.

Derivation: A standard glass formula to which a

nucleating agent, such as titania, has been added, is

Glaser coupling. Coupling of terminal acety-

melted, rolled into sheet, and cooled. It is then heat-

lenes by shaking an aqueous solution of cuprous

ed to a temperature at which nucleation occurs, caus-

chloride−ammonium chloride and the alkyne in an

ing formation of crystals.

atmosphere of air or oxygen.

Use: Range and stove tops, laboratory bench tops,

architectural panels, restaurant heating and warming

glass. A ceramic material consisting of a uniform-

equipment, telescope mirrors.

ly dispersed mixture of silica (sand) (75%), soda ash

See nucleation; “Pyroceram”; “Cer-vit.”

(20%), and lime (5%), often combined with such

metallic oxides as those of calcium, lead, lithium,

“Glassclad 6C” [United Chemical]. TM

cerium, etc., depending on the specific properties

for a chlorine terminated polydi methylsiloxane tel-

desired. The blend (or “melt”) is heated to fusion

omer.

temperature (approximately 700–800C) and then

Use: To form a siliconized surface.

gradually cooled (annealed) to a rigid, friable state,

often referred to as vitreous. Technically, glass is an

glass electrode. See electrode, glass.

amorphous, undercooled liquid of extremely high

viscosity that has all the appearances of a solid. It has

glass enamel. A finely ground flux, basically

almost 100% elastic recovery.

lead borosilicate, intimately blended with colored

See glass, optical.

ceramic pigments. Different grades give character-

Properties: (Soda-lime glass.) Lowest electrical

istics of acid resistance, alkali resistance, sulfide

conductivity of any common material (below 10

−6

resistance, or low lead release to meet requirements

mho/cm). Low thermal conductivity. High tensile

for various uses. Firing range 540–760C.

and structural strength. Relatively impermeable to

Use: For fired-on labels and decorations on glass-

gases. Inert to all chemicals except hydrofluoric,

ware, tumblers, milk bottles, beverage bottles, glass

fluosilicic, and phosphoric acids and hot, strong

containers, illuminating ware, architectural glass,

alkaline solutions. Continuous highest-use tempera-

and signs.

ture about 121C but may be higher, depending on

See porcelain enamel.

composition. Good thermal insulator in fibrous

form. Molten glass is extrudable into extremely fine

filaments. Glass is almost opaque to UV radiation;

glass fiber. (fibrous glass; fiberglass). Gener-

in the absence of added colorant it transmits 95–98% ic name for a manufactured fiber in which the fiber-

of light to which it is exposed. Noncombustible. forming substance is glass (Federal Trade Commis-

Occurrence: Natural glass is rare but exists in the sion). Noncombustible.

form of obsidian in areas of volcanic activity and Properties: Tensile strength 15 g/denier, elongation

meteor strikes. Excellent sand for glassmaking oc- 3–4%, d 2.54, no moisture regain, loses strength at

curs in Virginia (James River), Pennsylvania, Mas- >315C, softens at approximately 815C.

sachusetts, New Jersey, West Virginia, Illinois, and See glass.

Maryland; also in southern Germany and the Czech Derivation: Molten glass is extruded at high speed

Republic. through extremely small orifices.

Available forms: Plate, sheet, fiber, filament, fabric, Hazard: A suspected carcinogen. TLV: 10 mg/m

rods, tubing, pipe, powder, beads, flakes, hollow (dust).

spheres. Use: Thermal, acoustic, and electrical insulation

See sodium silicate. (coarse fibers in bats or sheets); decorative and utili-

Use: Windows, structural building blocks, chemical ty fabrics such as drapes, curtains, table linen, carpet

reaction equipment, pumps and piping, vacuum backing, tenting, etc.; tire cord as belt between tread

tubes, lightbulbs, glass fibers, yarns and fabrics, and carcass; filter medium; reinforced plastics; light

containers, optical equipment. Minute glass spheres transmission for communication signals; reinforce-

with partial vacuum interior and treated exterior are ment of cement products for construction use.

available for compounding with resins for use in See fiber, optical.

607 GLAUCONITE

glass, heat-resistant. (1) A soda-lime glass during cooling. Alkali borosilicates are the most

containing approximately 5% boric oxide, which

suitable types of glasses for this purpose.

lowers the viscosity of the silica without increasing

Use: Variable-tint prescription lenses that darken in

its thermal expansion. Such glasses (known as boro-

sunlight and return to original clearness indoors

silicates) have a very low expansion coefficient and

(85% light transmission when clear, 45% in sun-

high softening point (about 593C). Tensile strength

light).

is approximately 10,000 psi. Continuous-use tem-

perature 482C. Transmits UV light in higher wave-

glass, photosensitive. A glass containing a

lengths and is used in sunlight lamps and similar

small amount of a photosensitive substance such as a

equipment for this reason.

gold, silver, or copper compound. When UV light is

See “Pyrex.”

passed through a photographic negative onto the

Note: Use of borosilicate glass as a storage-disposal

surface of this glass, a latent image formed within

medium for high-level radioactive wastes has been

the glass is converted to a visible image made up of

under research for some time. Tentative conclusions

tiny metal particles when the glass is heated. In a

based on high-temperature and high-pressure auto-

special type of photosensitive glass (photosensitive

clave tests indicate that this method would be suit-

opal), the metal particles of the photographic image

able for geologic storage of such wastes.

within the glass serve as nuclei for the growth of

See radioactive waste.

nonmetallic crystals; crystalline growth is confined

(2) A pure silica glass trademarked “Vycor” that

to the area of the image. These crystalline areas are

softens at about 1482C.

dissolved much more rapidly than the adjacent glass

See silica, fused.

by hydrogen fluoride. Thus, the glass can be formed

into intricate shapes without the use of mechanical

glassine. A thin, transparent, and very flexible

tools.

paper obtained by excessive beating of the pulp. It

may contain an admixture of urea formaldehyde to

glass, plate. Plate glass has the same composi-

improve strength.

tion as window glass (soda-lime silica), differing

Use: Packaging, dust covers for books; general

from it only in method of manufacture. These differ-

household purposes.

ences are primarily (1) the longer time of annealing

(3 or 4 days), which eliminates the distortion and

glassmaker’s soap. Term for manganese diox-

strain effects of rapid cooling; and (2) intensive

ide (MnO

grinding and polishing, which removes local imper-

fections and produces a bright, highly reflecting

glass, metallic. Metal alloys having an amor-

finish.

phous atomic structure similar to that of silica glass;

achieved by cooling of the molten alloy so rapidly

glass, ruby. A deep-red glass made by incorpo-

that no crystalline structure is formed. Such alloys

rating colloidal gold into the silicate mixture. It is

are said to be harder than their crystalline counter-

used chiefly in the decorative arts.

parts and are more resistant to corrosion. Those

containing iron have unusual ferromagnetic proper-

glass, safety. See safety glass.

ties that make them suitable for use as transformer

coils.

glass transition temperature. (T

). The

See “Metglas.”

temperature at which an amorphous material (such

as glass or a high polymer) changes from a brittle

glass, optical. Glasses intended for vision cor-

vitreous state to a plastic state. Many high polymers,

recting and such applications as lenses for cameras,

such as acrylics, and their derivatives have this tran-

microscopes, and other instruments; must be of ex-

sition point, which is related to the number of carbon

tremely high quality and uniformity to meet require-

atoms in the ester group. The T

depends on its

ments for refractive index and light dispersion. Opti-

composition and extent of annealing.

cal glass may be either crown (lime) or flint (lead).

Lead oxide is a major ingredient of flint glass, im-

glass, water. See sodium silicate.

parting high refractive index and dispersion, as well

as surface brilliance. Flint glasses are also used in

Glauber’s salt. See sodium sulfate decahyd-

vacuum tubes and electrical equipment. Many spe-

rate.

cial ingredients are used in both crown and flint

glasses for specific refractivity and dispersion prop-

erties.

glauconite. K

(Mg, Fe)

(Si

)

(OH)

natural silicate of potassium, aluminum, iron, and

glass, photochromic. A glass that changes col- magnesium found in greensands and other sedimen-

or on exposure to light and returns to original color tary rocks.

when the light has been removed. One type is a Properties: Green in color, earthy luster. D 2.3.

silicate glass containing dispersed crystals of colloi- Occurrence: New Jersey, Virginia.

dal silver halide that is precipitated within the melt Use: Water softener, foundry molds, fertilizer.

608ALLO-GLAUCOTOXIGENIN

allo-glaucotoxigenin. isms. They are coagulated by heat; insoluble in wa-

CAS: 14155-65-8. mf: C

. ter; soluble in dilute solutions of salts, strong acids,

Hazard: A poison. and strong alkalies. Enzymes and acids cause hy-

Source: Natural product.

drolysis to amino acids as the only products. Exam-

ples are immune serum or ␥-globulins in blood and

glaze. A mixture similar to porcelain enamel, ap-

myosin in muscle. The blood globulins are used in

plied to a ceramic substrate. It may refer to (1) a

immunizing against specific diseases and in medical

vitreous coating on pottery or enamelware; (2) the

research. The ␥-globulin molecule is reported to

mixed dry powders of the batch to be used for the

consist of 19,996 atoms associated in 1320 amino

coating; or (3) a water suspension of these materials

acid units.

(wet glaze). Glazes must be low in sodium and are

(2) A protein occurring naturally in wheat and other

usually mixtures of silicates and flint, lead com-

cereal grains. See immunochemistry.

pounds, boric acid, calcium carbonate, etc.

See frit; porcelain enamel.

␥-globulin. See immune endoglobulin.

glaze stain. Finely ground calcined oxide of

GLP. (good laboratory practices). Refers to the

cobalt, copper, iron, and manganese.

body of regulations that govern the collection of

Use: Coloring ceramic glazes.

laboratory data. As two examples, data collected

must be traceable to the exact person who collected

GLC. Abbreviation for gas-liquid chromatogra-

the data, and computer files must have their name

phy.

changed if the file contents change.

See gas chromatography.

Glu. Abbreviation for glutamic acid.

gliadin. A prolamin occurring in gluten, the pro-

tein of wheat, rye, and other grains. Wheat gliadin

glucagon. (hyperglycemic-glycogenolytic fac-

has the following composition: 52.7% carbon,

tor; HG-factor; HGF). Produced by the ␣ cells of

17.7% nitrogen, 21.7% oxygen, 6.9% hydrogen,

the islands of Langerhans and also by the gastric

1.0% sulfur. It is composed of 18 amino acids, 40%

mucosa. It is opposite in effect to insulin. It appears

being glutamic acid. Insoluble in water, soluble in

to be a straight-chain polypeptide with a molecular

70–90% alcohol, soluble in dilute acid and in alkali.

weight of approximately 3500. Small amounts have

Use: Chemical synthesis of spinal anesthetics, phar-

been detected in commercial insulin preparations.

maceutical preparations.

Grade: USP.

Use: Medicine, biochemical research.

gliftor.

CAS: 8065-71-2. mf: C

ClFO•C

“Glucam E-10” [Dow]. TM for humectant

Hazard: A poison by ingestion, inhalation, and skin

from corn.

contact. An eye irritant.

Use: To reduce overall irritancy from other ingredi-

ents in hair- and skin-care preparations.

gliquidone.

CAS: 33342-05-1. mf: C

“Glucam E-20” [Dow]. TM for humectant

Hazard: Low toxicity by ingestion. A reproductive

from corn.

hazard.

Use: For a highly active, mild skin moisturizer that

reduces water loss from cream and lotion formula-

“Globar” [Carborundum]. TM for silicon

tions.

carbide heating elements and resistors and acces-

sories.

“Glucam P-20” [Dow]. TM for a fragrance

Properties: Elements have a working temperature up

fixative.

to 1510C, which can be extended to 1648C for short

periods; low coefficient of expansion; structure not

glucase. See maltase.

affected by rapid heating and quick cooling; resis-

tance remains practically constant above 482C.

glucinium. Former name for the element berylli-

Use: Electric resistors and heating elements, termi-

um, named because the salts of beryllium are sweet

nals, and other accessories for electric heating ele-

tasting.

ments, electric heating appliances, electric furnaces.

glucocorticoid response element. See

globular proteins. Soluble proteins with a

GRE.

globular (somewhat rounded) shape. Their axial to

diameter ratio is less that 10:1, and usually closer to

1:1.

glucogenic amino acids. Amino acids with

carbon chains that can be metabolically converted

globulin. (1) Any of a group of proteins synthe- into glucose via gluconeogenesis. Contrast with ke-

sized by the body when invaded by infective organ- togenic amino acids.

609 GLUE

gluconeogenesis. The biosynthesis of a carbo- and wine making, intermediate, caramel coloring,

hydrate from simpler, noncarbohydrate precursors baking and canning, source of methane by anaerobic

such as alanine or pyruvate. fermentation, source of certain amino acids (e.g.,

lysine) by fermentation.

See glucose syrup; invert sugar.

gluconic acid. (glyconic acid; glycogenic

acid).

glucose isomerase enzyme preparations,

CAS: 299-27-4. CH

OH(CH

COOH.

insoluble.

Properties: Pure product is crystalline; light-brown

Use: Food additive.

color. Mp 131C, d 1.24. Commercial grade is 50%

aqueous solution. Insoluble in organic solvents.

glucose oxidase. An enzyme commercially

Derivation: Bacterial, chemical, or electrochemical

available under various trademarks; catalyzes oxi-

oxidation of glucose. It is the chief acid in honey.

dation of glucose to gluconic acid. Water-soluble

Grade: Technical, 50% solution.

amorphous powder. Removes excess oxygen from

Use: Pharmaceutical and food products, cleaning and

canned foods, beer, etc., and from stored food.

pickling metals, sequestrant, cleansers for bottle

Use: Food preservative, analytical reagent for glu-

washing, paint strippers, alkaline derusters, catalyst

cose, stabilizer for vitamins C and B

in textile printing (ammonium salt).

glucose syrup. (corn syrup). A mixture of D-

glucono-⌬-lactone. (D-gluconic acid, ⌬-lac-

glucose, maltose, and maltodextrins made by hy-

tone).

drolysis of cornstarch by the action of acids or en-

CAS: 90-80-2. CH

OHCH(CH

C(O)O.

zymes. The degree of conversion of the starch varies

Properties: White crystals. Mp 155C, bp (decom-

with consequent effect on the dextrose equivalent

poses). Readily soluble in water; slightly soluble in

(DE) or reducing power of the syrup.

alcohol.

Use: Food industry as a sweetener (high DE), thick-

Derivation: Oxidation of glucose.

ener, or bodying agent (low DE) in soft drinks.

See gluconic acid.

See glucose.

8-␤-d-glucopyranosyl-apigenin.

␣-glucosidase. See maltase.

CAS: 3681-93-4. mf: C

Hazard: A poison.

␤-glucosidase. See emulsion.

D(+)-glucosamine.

glucoside. See glycoside.

OH(CH

CHNH

CHO.

Properties: (␤ form.) Colorless needles. Mp 110C

“Glucquat 100” [Dow]. TM for humectant

(decomposes). Very soluble in water; slightly solu-

from corn.

ble in methanol and ethanol; insoluble in ether and

Use: For conditioning, plasticizing, and foam reten-

chloroform.

tion.

Use: Biochemical research.

D(+)-glucuronic acid. COOH(CH

CHO. A

glucose. (dextrose; grape sugar; corn sugar).

widely distributed substance in both plants and ani-

CAS: 50-99-7.

mals, usually occurs as part of a larger molecule as in

various gums or combined with phenols or alcohols.

Properties: Needle-like crystals. Exhibits mutarota-

tion; the ␤ form has mp 165C. Soluble in water and

alcohol.

Derivation: From gum acacia.

Use: Biochemical research, medicine.

D-glucuronolactone.

CAS: 32449-92-6. C

. The ␥-lactone of glucu-

ronic acid. Found in plant gums and animal connec-

Properties: Colorless crystals or white granular

tive tissues.

powder; odorless; sweet taste. D 1.544, mp 146C.

Properties: Colorless or white powder; odorless. D

Soluble in water; slightly soluble in alcohol. It has

1.76 (30/4C), mp 172–178C. Soluble in water.

the

D (right-handed) configuration and is dextrorota-

Derivation: From glucuronic acid or by synthesis.

tory. Combustible.

Use: Growth factor, medicine, pharmaceutical inter-

Occurrence: Formed in plants by photosynthesis,

mediate.

also in the blood.

Derivation: Hydrolysis of cornstarch with acids or

enzymes, hydrolysis of cellulosic wastes.

glue. A colloidal suspension of various proteina-

Grade: Technical, USP, anhydrous, hydrated. ceous materials in water. Most familiar are those

Use: Confectionery, infant foods, medicine, brewing derived by boiling animal hides, tendons, or bones,

610GLUEGLIS

which are high in collagen. Chief sources are Hazard: A poison.

slaughterhouse wastes and fish scraps. Other ani-

mal-derived glues are made from casein (milk) and

␥-glutamylcysteinylglycine. See glutathion.

blood. The most important vegetable glue is made

from soybean protein. Combustible in solid form.

glutaraldehyde.

See adhesive; fish glue; collagen; gelatin.

CAS: 111-30-8. OCH(CH

)

CHO.

Properties: Liquid. D 0.72, bp 188C (decomposes),

Glueglis. TM for a composition containing chief-

fp −14C, vap press 17 mm Hg (20C). Soluble in

ly glue and glycerol used in printing-press rollers.

water and alcohol. No flash point. Nonflammable.

Has soft, rubbery consistency but is easily decom-

Grade: 99%, 50% biological solution, 25% solution.

posed by heat.

Hazard: Irritant. TLV: ceiling 0.2 ppm.

Use: Intermediate; fixative for tissues; cross-linking

glufosinate.

protein and polyhydroxy materials, tanning of soft

CAS: 53369-07-6. mf: C

leathers.

Hazard: Moderately toxic by ingestion.

Use: Agricultural chemical.

glutaric acid. (n-pyrotartaric acid; pentane-

dioic acid).

gluside. See saccharin.

CAS: 110-94-1. HOOC(CH

)

COOH.

Properties: Colorless crystals. Mp 97C; refr index

1.419 (106C). Soluble in water, alcohol, ether, ben-

glutamic acid. (␣-aminoglutaric acid; 2-ami-

zene, and chloroform.

nopentanedioic acid).

Derivation: From cyclopentanone.

CAS: 56-86-0. COOH(CH

)

CH(NH

)COOH. A

Use: Organic synthesis, biochemical research.

nonessential amino acid. The naturally occurring

form is

L(+)-glutamic acid.

Properties:

DL-glutamic acid (synthetic racemic glutaric anhydride. (pentanedioic acid anhy-

mix): crystals. Mp 224–227C (decomposes). Slight- dride). H

C(CH

CO)

ly soluble in ether, alcohol, and petroleum ether. D Properties: Solid. Mp 56.5C, bp 303C. Soluble in

1.4601 (20/4C). Moderately soluble in water

L(−)- benzene and toluene; soluble in water on complete

glutamic acid. Mp 247–249C (decomposes), d 1.538 hydrolysis.

(20/4C)

L(+)-glutamic acid: crystals. Sublimes at Hazard: Irritant.

200C, decomposes at 247–249C. Slightly soluble in Use: Plasticizers, resin, lubricant, adhesive synthesis,

ether, acetone, cold glacial acetic acid; insoluble in dyes, and pharmaceuticals.

alcohol. D 1.538 (20/4C), specific rotation +37 to

+38.9 degrees (25C). Available commercially.

glutaronitrile. (trimethylenedicyanide; penta-

Derivation: Hydrolysis of vegetable protein (e.g.,

nedinitrile).

beet sugar waste, wheat gluten), organic synthesis

CAS: 544-13-8. NC(CH

)

CN.

based on acrylonitrile. It comprises 40% of the

Properties: Colorless to straw-colored, viscous liq-

gliadin in wheat gluten.

uid. Bp 286C, d 0.989. Soluble in water and alcohol;

Grade: FCC (

L-form).

insoluble in ether and carbon disulfide. Combus-

Use: Medicine, biochemical research, salt substitute,

tible.

flavor enhancer (

L-form only).

Use: Chemical intermediate.

See sodium glutamate.

glutathione. (␥-glutamylcysteinylglycine).

glutamine. (2-amino-4-carbamoylbutanoic

CAS: 70-18-8. C

S. A universal component

acid).

of the living cell. Contains glutamic acid, cysteine,

CAS: 56-85-9. H

NC(O)(CH

)

CH(NH

)COOH. A

and glycine. These are chemically bound but can be

nonessential amino acid. Both the

L- and DL-forms

separated by hydrolysis.

are available.

Properties: White, crystalline powder; odorless;

Properties: White, crystalline powder. Soluble in

mild, sour taste. Mp 190–192C. Soluble in water and

water; insoluble in most organic solvents. Should be

dilute alcohol.

kept dry and refrigerated. Mp (

L-form) 184–185C

Use: Nutritional and metabolic research.

(decomposes) (

DL-form) 176C. Its presence in wheat

gluten contributes to the elastic properties of flour

gluten. A mixture of many proteins in which

by hydrogen bonding and disulfide cross-linking.

gliadin, glutenin, globulin, and albumin predomi-

Derivation: Action of enzymes on gluten, from beet

nate; it occurs in highest percentage in wheat (Mani-

roots, constituent of many proteins.

toba wheat contains approximately 12%) and also to

Use: Medicine, culture media, biochemical research,

some extent in other cereal grains, usually associ-

feed additive.

ated with starch. It comprises 18 amino acids. Glu-

ten is insoluble in water and hydrophilic. Its specific

7-n-((2-((2-(glutamylamino)ethyl) adaptability to bread making is due to its elastic,

dithio)ethyl))mitomycin c. cohesive nature that enables it to retain the bubbles

CAS: 118359-59-4. mf: C

. of carbon dioxide evolved by leavening agents; this

611 GLYCEROL

also imparts to doughs their characteristic dilatant glycerol have been replaced by acid radicals. The

latter may be identical or different so that the glycer-

properties. This behavior is due to disulfide cross-

ide may contain up to three different acid groups.

links and hydrogen bonding between the proteins or

Glycerides can be made synthetically. The most

their constituent amino acids.

common are based on fatty acids that occur naturally

Use: Special breakfast foods and other cereals and

in oils and fats.

foods, cattle food, adhesives, production of certain

See monoglyceride; triglyceride.

amino acids.

glutenin. One of the proteins present in wheat

glycerin. See glycerol.

flour in substantial percentage. It is composed of 18

amino acids.

glycerin carbonate. (hydroxymethylethylene

carbonate).

Gluten Intolerance Group. (GIG). A non

profit group that provides support to persons with

❘

O(CO)O

❘

CHCH

OH.

gluten intolerances, including Celiac Disease, Der-

Properties: Pale-yellow hygroscopic liquid;

matitis Herpetiformis and other gluten sensitivities.

odorless. Boiling range 125–130C (0.1–0.2 mm

Its mailing address is 15110 10th Ave., SW, Seattle,

Hg), fp supercools to a glass, d 1.4000 (20/4C), refr

WA 98166. Website: http:/./www.gluten.net

index 1.4580 (20C), flash p 415F (212C). Miscible

with water, alcohol, ether; soluble in ethylene di-

gluten sensitive enteropothy. (GSE).

chloride; insoluble in carbon tetrachloride, benzene,

See: celiac disease.

and aliphatic hydrocarbons. Combustible.

Grade: Technical.

glutethimide. See 2-ethyl-2-phenylglutari-

Use: Solvent, intermediate.

mide.

glycerin 1-isopropyl ether.

Gly. Abbreviation for glycine.

CAS: 17226-43-6. mf: C

Hazard: Low toxicity by ingestion and inhalation. A

glycan. A general term for a polymer of monosac-

mild skin and eye irritant.

charide units joined by glycosidic bonds, may or

may not have other components, e.g. peptidoglycan.

glycerol. (glycerin; glycyl alcohol; 1,2,3-pro-

panetriol).

glycarbylamide. (4,5-imidazoledeicarboxam-

CAS: 56-81-5.

ide). C

(CONH

)

Properties: White powder. Melts above 360C. Insol-

uble in water.

Use: A coccidiostat for chickens.

glyceraldehyde. (glyceric aldehyde).

A trihydric (polyhydric) alcohol.

CAS: 56-82-6. HOCH

OCHO. Isomeric with

Properties: Clear, colorless, syrupy liquid; odorless;

dihydroxyacetone. It is produced by the oxidation of

sweet taste; hygroscopic. D anhydrous 1.2653, USP

sugars in the body. As the simplest aldose, the con-

greater than 1.249 (25/25C), dynamite 1.2620, mp

formation of

D- and L-glyceraldehydes has been des-

18C, bp 290C, flash p 320F (160C), autoign temp

ignated the reference standard for

D- and L-carbohy-

739F (392C). Soluble in water and alcohol (aqueous

drates and derivatives.

solutions are neutral); insoluble in ether, benzene,

and chloroform and in fixed and volatile oils. Com-

bustible.

Derivation: (1) By-product of soap manufacture; (2)

from propylene and chlorine to form allyl chloride,

which is converted to the dichlorohydrin with hypo-

In these isomers, the central carbon atom (C*) is

chlorous acid; this is then saponified to glycerol with

asymmetric.

caustic solution; (3) isomerization of propylene ox-

Properties: (

DL-glyceraldehyde.) Tasteless crystals

ide to allyl alcohol, which is reacted with peracetic

from alcohol-ether mixture. Mp 145C. Insoluble in

acid, (the resulting glycidol is hydrolyzed to glycer-

benzene, petroleum ether, pentane.

ol); (4) hydrogenation of carbohydrates with nickel

Grade: 40% aqueous solution.

catalyst; (5) from acrolein and hydrogen peroxide.

Use: Biochemical research; intermediate; nutrition;

Method of purification: Redistillation, ion-ex-

prepraration of polyesters, adhesives; cellulose

change techniques.

modifier; leather tanning.

Grade: USP, CP (pharmaceutical and commercial,

where highest grade is required), saponification

glyceride. An ester of glycerol and fatty acids in soap lye, crude yellow distilled (for commercial

which one or more of the hydroxyl groups of the purposes where color and extreme purity are not

612GLYCEROL BORIBORATE

factors), high gravity or dynamite (dehydrated to

glycerol-lacto stearate.

Use: Food additive.

99.8–99.9% purity), natural, synthetic, FCC.

Hazard: TLV: (vapor) 10 mg/m

Use: Alkyd resins, dynamite, ester gums, pharmaceu-

glycerol monolaurate. (glyceryl monolau-

ticals, perfumery, plasticizer for regenerated cellu- rate). C

COOCH

OCH

OH.

Properties: Cream-colored paste; faint odor. Mp

lose, cosmetics, foodstuffs, conditioning tobacco,

23–27C, d 0.98, FFA <2.5%, iodine value 5–8, pH

liquors, solvent, printer’s ink rolls, polyurethane

8.0–8.6 (25C) (5% aqueous dispersion). Dispersible

polyols, emulsifying agent, rubber stamp and copy-

in water; soluble in methanol and ethanol, toluene,

ing inks, binder for cements and mixes, special

naphtha, mineral oil, cottonseed oil, ethyl acetate.

soaps, lubricant and softener, bacteriostat, pene-

Combustible.

trant, hydraulic fluid, humectant, fermentation nu-

See monoglyceride.

trients, antifreeze mixtures.

Grade: Edible, technical.

Use: Emulsifying and dispersing agent for food prod-

glycerol boriborate.

ucts, oils, waxes, and solvents; antifoaming agent;

Properties: Pale-yellow liquid obtained by heating

dry-cleaning soap base.

glycerol, sodium borate, and boric acid; composi-

tion varies, soluble in cold water, absolute alcohol,

glycerol monooleate.

other alcohols, glycerol.

CAS: 25496-72-4.

Use: Adhesive, binder, fabric softener, fire-retardant

Properties: Clear amber or pale yellow liquid. Insol

on fabrics.

in water.

Use: Food additive.

glycerol dichlorohydrin. See ␣-dichloroh-

See “Aldo MO” [Ashland].

ydrin.

glycerol monooleate. (glyceryl monooleate).

glycerol-1,3-distearate. (glyceryl-1,3-distea-

COOCH

OCH

OH.

rate). C

Properties: Yellow oil or soft solid. D 0.95, mp

Properties: Solid. Mp 29.1. Very slightly soluble in

14–19C depending on purity, iodine value 65–80.

cold alcohol and ether; soluble in hot organic sol-

Insoluble in water; somewhat soluble in alcohol and

vents.

most organic solvents. Combustible.

See monoglyceride.

glycerol ester of partially dimerized rosin.

Grade: Edible, technical.

Properties: Hard, pale amber-colored resin. Sol in

Use: Foods, pharmaceuticals, and cosmetics; rust-

acetone, benzene; insol in water.

preventive oils; textile finishing; vinyl light stabiliz-

Use: Food additive.

ers; odorless base paints, flavoring.

glycerol ester of partially hydrogenated

glycerol monoricinoleate. (glyceryl monori-

wood rosin.

cinoleate).

Properties: Medium hard, pale amber resin. Sol in

COOCH

OCH

OH.

acetone, benzene; insol in water, al