H. Symbol for hydrogen, the molecular formula is 5400C, high thermal neutron cross section (115

barns). Good corrosive resistance and high strength.

See zirconium.

Occurrence: Zirconium ores.

h. See Planck’s constant.

Derivation: Extremely difficult to separate from zir-

conium. Most important methods are: (1) solvent

Haber, Fritz. (1868–1934). Born in Breslau,

extraction of the thiocyanates by hexone, (2) solvent

Germany, Haber’s great contribution to chemistry,

extraction of the nitrates by tributyl phosphate, (3)

for which he was awarded the Nobel Prize in 1918,

fractional crystalization of the double fluorides.

was his development (with Bosch) of a workable

Available forms: Powder, rods, single crystals.

method for synthesizing ammonia by the water-gas

Hazard: Toxic by inhalation; compounds are also

reaction from hot coke, air, and steam; the gas mix-

toxic. Powder form is explosive in air, either dry or

ture obtained includes nitrogen from the air, as well

wet, with less than 25% water. TLV: 0.5 mg/m

as hydrogen from the steam. It was the first success-

Use: Control rods in water-cooled nuclear reactors;

ful attempt to “fix” atmospheric nitrogen in an in-

lightbulb filaments, electrodes, special glasses, get-

dustrial process. This discovery was developed to

ter in vacuum tubes.

production scale in approximately 1912; it enabled

Germany to manufacture an independent supply of

hafnium boride. HfB

. Crystalline solid, mp

explosives for World War I.

3100C.

Use: Refractory material.

habit. The type of geometric structure that a given

crystalline material invariably forms, e.g., cubic,

hafnium carbide. HfC.

orthorhombic, monoclinic, tetragonal, hexagonal,

Properties: High thermal neutron absorption cross

etc. Each of these types has several subclasses.

section. Very high mp 3890C (7030F). Most refrac-

Thus, crystals may have the form of thin sheets or

tory binary substance known.

plates, cubes, rhomboids, and even more complicat-

Use: Control rods in nuclear reactors.

ed geometric structures. For example, the crystalline

habit of mica is monoclinic, with formation of ex-

tremely thin sheets.

hafnium disulfide. HfS

. Available in a particle

See crystal.

size of 40 microns as a solid lubricant. The diselen-

ide and ditelluride are also available.

H acid. (1-amino-8-napthol-3,6-disulfonic

acid).

hafnium nitride. HfN. Yellow-brown crystals,

Properties: Gray powder. Soluble in water, alcohol,

mp 3305C, the most refractory of known metal ni-

and ether.

trides.

hafnium oxide. (hafnia). HfO

Properties: White solid. D 9.68 (20C), mp 2812C, bp

approximately 5400C. Insoluble in water.

Use: Refractory metal oxide.

Hahn, Otto. (1879–1968). A German physical

Derivation: Fusion of 1-naphthylamine-3,6,8-trisul-

chemist who won the Nobel Prize for chemistry in

fonic acid (Koch acid) with 30% sodium hydroxide

1944 for atom splitting and the principle of the chain

solution at 180C.

reaction. Well-known for work on nuclear fission he

Use: Azo dye intermediate.

discovered protactinium and transuranium elements

with atomic numbers 94, 95, and 96. After receiving

his doctorate at the University of Munich, he worked

haemo-. Prefix indicating relationship to blood.

in Canada before returning to Europe.

hafnia. See hafnium oxide.

hair. See keratin.

hafnium.

CAS: 7440-58-6. Hf. Metallic element of atomic halazone. (p-N,N-dichlorosulfamylbenzoic

number 72, Group IVB of the periodic table, aw acid; p-sulfondichloraminobenzoic acid).

178.49, valences of 2, 3, 4; 6 stable isotopes. CAS: 80-13-7. HOOCC

NCl

Properties: Generally similar to zirconium. Gray Properties: White crystalline powder; strong chlo-

crystals. D 13.1, mp approximately 2150C, bp above rine odor. Mp 195C with decomposition. Affected

628

629 HALOGENATION

by light. Soluble in glacial acetic acid, benzene; alumina extracted from it (see Bayer process). A

slightly soluble in water, chloroform; insoluble in typical cell for this process consists of a rectangular

petroleum ether. steel shell lined with insulating brick and block

carbon. The cell holds a molten cryolite-alumina

Grade: NF.

electrolyte, commonly called the “bath.” The carbon

Use: Water disinfectant.

bottom is covered by a pad of molten aluminum and

serves as the cathode. The anodes are prebacked

half-life. The time required for an unstable ele-

carbon blocks suspended in the electrolyte. The ca-

ment or nuclide to lose one-half of its radioactive

thodic current is collected from the carbon bottom

intensity in the form of ␣, ␤, and ␥ radiation. It is a

by embedded steel bars that protrude through the

constant for each radioactive element or nuclide.

shell to connect with the cathode bus. During elec-

Half-lives vary from fractions of a second for some

trolysis, aluminum is deposited on the metal pad,

artificially produced radioactive elements to mil-

and the oxygen, liberated at the anode, reacts with

lions of years. The half-life of

235

U is 7.1 × 10

years;

the carbon to form carbon dioxide, some of which is

that of

239

Pu is 24,360 years.

reduced to carbon monoxide by secondary reac-

tions. At 24–48-h intervals, aluminum is tapped

halibut liver oil. (haliver oil).

from the cell by a siphon. The process requires large

Properties: Pale-yellow to dark-red liquid; fishy

amounts of electric power (from 4–5% of total U.S.

odor and taste. D 0.920–0.930, saponification num-

production). Disposition of the toxic fluoride waste

ber 160–180, iodine number 120–136, refr index

is a problem.

about 1.47. Soluble in alcohol, ether, chloroform,

See Toth process.

and carbon disulfide; insoluble in water.

Derivation: By expressing and boiling halibut livers.

hallucinogen. Any of a number of drugs acting

Grade: Crude, refined.

on the central nervous system in such a way as to

Use: Source of vitamins A and D, leather dressing.

cause mental disturbance, imaginary experiences,

coma, and even death. Many of these are narcotics

halides. Binary compounds of the halogens.

and/or alkaloids; some are derived from plants, and

others are made synthetically. They differ in degree

halite. The mineral that consists of sodium chlo-

of addiction and hallucinatory effect. Their sale and

ride (NaCl), popularly known as rock salt, or the

possession (other than by physicians) is illegal in the

rock that consists primarily of this mineral.

U.S. The most common hallucinogens are cannabis

(marijuana, hashish), lysergic acid (LSD), amphet-

Hall, Charles Martin. (1863–1914). A native

amine, and numerous morphine derivatives.

of Ohio, Hall invented a method of reducing alumi-

num oxide in molten cryolite by electrochemical

halocarbon. A compound containing carbon,

means. This discovery made possible the large-scale

one or more halogens, and sometimes hydrogen.

production of metallic aluminum and resulted in

The lower members of the various homologous se-

formation of the Aluminum Company of America.

ries are used as refrigerants, propellant gases, fire-

The process requires high electric power input. Hall

extinguishing agents, and blowing agents for ure-

is generally considered the founder of the aluminum

thane foams. When polymerized, they yield plastics

industry.

characterized by extreme chemical resistance, high

See Hall process.

electrical resistivity, and good heat resistance.

See fluorocarbon.

“Hallco” [Hall]. TM for specialty esters based

on acetic, lauric, and sebacic acids.

halocarbon 112a. See 1,1,2-tetrachloro-2,2-

difluoroethane.

“Hallcomid” [Hall]. TM for a series ofN,N

′

dimethyl amides and esters of fatty acids.

halofuginone hydrobromide.

mf: C

CIN

“Hallcote” [Hall]. TM for clay containing anti-

Properties: Crystals.

blocking coatings (slab dips) used in rubber pro-

Use: Drug (veterinary); food additive.

cessing.

halogen. One of the electronegative elements of

Haller-Bauer reaction. Cleavage of nonenol-

group VII A of the periodic table (fluorine, chlorine,

izable ketones with sodium amide, most often ap-

bromine, iodine, astatine, listed in order of their

plied to ketones ArCOCR

to yield trisubstituted

activity, fluorine being the most active of all chemi-

acetic acids.

cal elements).

halloysite. Al

•3SiO

•2H

O. A clay used in

refactories and as a catalyst support.

halogenation. Incorporation of one of the halo-

gen elements, usually chlorine or bromine, into a

Hall process. The electrolytic recovery of alu- chemical compound. Thus benzene (C

) is treated

minum from bauxite or, more specifically, from the with chlorine to form chlorobenzene (C

Cl), and

630“HALON”

ethylene (C

) is treated with bromine to form Hamiltonian function. An expression of the

sum of potential and kinetic energy in a system in

ethylene dibromide (C

). Compounds of chlo-

terms of Cartesian coordinates and momenta.

rine and bromine are sometimes used as the source

of the halogen, e.g., phosphorus pentachloride.

hammer mill. A crushing or shredding device

“Halon” [Great Lakes]. TM for tetrafluoro-

consisting of four or more rectangular metal ham-

ethylene polymer.

mers or sledges mounted on a rotating shaft, the

Properties: Inertness to almost all chemicals, resis-

hammers being free to swing on a pin. As the shaft

tance to high and low temperatures, zero moisture

rotates, the hammers impact the material introduced

absorption, high impact strength, excellent dielec-

from above, crushing it against a stationary breaker

tric properties, nonstick surface with low coefficient

plate. The fragments are carried downward and sort-

of friction, self-extinguishing (ASTM D-635).

ed by a grid located beneath the shaft; those too large

Grade: Varies with particle size as 600-, 300-, 20-

to pass through it are returned for another cycle. A

micron average size.

complete mill is made up of several such units work-

See polytetrafluoroethylene; fluorocarbon polymer.

ing on a single shaft, with suitable housing. Products

such as coal, limestone, and other mineral aggre-

“Halon 1211” [Great Lakes]. (bromochlo-

gates, as well as wood, sugarcane, and similar mate-

rodifluoromethane).

rials, can be effectively disintegrated with equip-

CAS: 353-59-3. TM for a compressed gas.

ment of this type.

Use: Fire-extinguisher compound.

Hammick reaction. Decarboxylation of ␣-pi-

Halon 1301. See trifluorobromomethane.

colinic or related acids in the presence of carbonyl

compounds accompanied by the formation of a new

halosafen. See 5-(2-chloro-6-fluoro-4-(trifluo-

carbon-carbon bond.

romethyl)phenoxy)-n.

Hammond-Leffler postulate. States that the

halothane. (2-bromo-2-chloro-1,1,1-trifluoroe-

structure of the transition state more closely resem-

thane).

bles the product or the starting material, depending

CAS: 151-67-7. CF

CHBrCl.

on which is higher in enthalpy.

Properties: Colorless, volatile liquid; sweetish odor.

D 1.872–1.877 (20/4C), bp 50.2C, 20C (243 mm

“Hampamide” [Grace]. TM for mixtures of

Hg). Light sensitive. May be stabilized with 0.01%

mono-, di-, and triamides of nitrailotriacetic acid in

thymol. Slightly soluble in water; miscible with

solution of dry salt form.

many organic solvents.

Grade: USP.

“Hamp-ene” [Grace]. TM for chemical com-

Hazard: TLV: 50 ppm; not classifiable as a human

positions comprising amino acid or carbohydrate

carcinogen.

chelating or sequestering agents or compositions

Use: Medicine (anesthetic).

containing such sequestering agents.

Available forms: Bulk and package.

Halowax 1051. See octachloronaphthalene.

Hamilton, Alice. (1869–1970). The first Amer-

“Hamp-Ex” [Grace]. TM for chemical com-

ican physician to devote her life to the practice of

positions comprising amino acid or carbohydrate

industrial medicine. In studying the lead industries

chelating or sequestering agents or compositions

in Illinois, she discovered and ameliorated lead poi-

containing such sequestering agents.

soning among bathtub enamelers in Chicago. She

Available forms: Bulk and package form.

wrote about phossy jaw, which occurred among

American matchmakers who used white or yellow

“Hampirex” [Grace]. TM for chelated micro-

phosphorus. She studied the effects of carbon mon-

nutrients.

oxide among steelworkers, the toxicity of nitroglyc-

erin among munitions makers during World War I,

“Hamp-Iron” [Grace]. TM for iron chelates

the symptoms of hatters exposed to mercury in Dan-

for agricultural purposes.

bury, Connecticut, and the “dead fingers” syndrome

of workers utilizing the early jackhammers. She also

“Hamp-Ol” [Grace]. TM for chemical compo-

described the toxic effects to the blood-forming cells

sitions comprising amino acid or carbohydrate che-

from benzol, and the neurologic and psychological

lating or sequestering agents or compositions con-

responses of workers in the viscose rayon industry.

taining such sequestering agents.

In 1919, Dr. Hamilton was appointed assistant pro-

Available forms: Bulk and package form.

fessor of industrial medicine at Harvard Medical

School. The first woman on the Harvard faculty, she

gave occupational medicine respectability as an aca-

“Hamposyl” [Grace]. TM for chemically

demic pursuit. modified fatty acids.

631 HARDY-WEINBERG LAW

“Hampshire” [Grace]. TM for chemical prod- haplotype. A way of denoting the collective ge-

ucts, namely, amino acids, chelating agents, metal

notype of a number of closely linked loci on a chro-

chelates, surfactants, sequestering agents, and

mosome.

resins.

haptoglobin. A serum protein which binds free

hemoglobin for transport to the liver for destruction.

“Hamp-Tex” [Grace]. TM for chelating agent

for textile applications.

“Harborlite” [World Minerals]. TM for

perlite minerals and mineral substances.

hand. (handle). A term used chiefly in the textile

Use: Filtration for industry, agriculture, horticulture,

industry to describe a fabric in a qualitative manner,

and forestry applications.

as determined by the sensory perception of its feel-

ing. It is also used to some extent in the leather

hard. A nontechnical word, used by chemists, that

industry. Such pragmatic physical-perception tests

has a variety of meanings. It describes the following:

are of great practical value, although the properties

(1) Water in which calcium carbonate or calcium

being ascertained are often not objectively defina-

sulfate is present.

ble.

See water, hard.

See texture.

(2) An acid having high positive oxidation and

whose valence electrons are not readily excited.

handedness. See asymmetry; enantiomer;

See acid.

chiral.

(3) Extremely short-wave radiation, e.g., hard X

rays.

“Hansa” [BASF]. TM for a group of yellow to

(4) The resistance of a pesticide or detergent to

orange, insoluble azo pigments based on toluidine

biodegradation.

and ␤-naphthol. Have good light fastness in deep

(5) Rubber cured with 30% or more of sulfur. See

shades but tend to fade in pastels. Notably poor

rubber, hard.

resistance to bleeding, good weather resistance, and

(6) Wood from deciduous trees. See hardwood;

relatively unaffected by acids and alkalies. Used

hardness.

chiefly in emulsion paints, toy enamels, and other

applications.

Harden, Sir Arthur. (1865–1940). An En-

glish chemist who won the Nobel Prize in chemistry

Hantach pyrrole synthesis. Formation of

in 1929 along with Hans von-Euler-Chelpin. He

pyrrole derivatives from ␣-chloromethyl ketone, ␤-

discovered fermentation enzymes and demonstrated

keto esters, and ammonia or amines.

the structure of zymase. His fermentation work

proved how inorganic phosphates speeded the pro-

cess. Born in England, he received his doctorate in

Hantzch pyridine synthesis. Synthesis of

Germany.

alkylpyridines by condensation of two moles of a ␤-

dicarbonyl compound with one mole of an aldehyde

hardness. The resistance of a material to defor-

in the presence of ammonia. The resulting dihydro-

mation of an indenter of specific size and shape

pyridine is dehydrogenated with an oxidizing agent.

under a known load. This definition applies to all

types of hardness scales except the Mohs scale,

Hanus reagent. Reagent consisting of 20% io-

which is based on the concept of scratch hardness

dine monobromide in glacial acetic acid.

and is used chiefly for minerals. The most generally

Use: Determination of iodine values.

used hardness scales are Brinell (for cast iron),

Rockwell (for sheet metal and heat-treated steel),

haploid. A single set of chromosomes (half the

diamond pyramid, Knoop, and scleroscope (for met-

full set of genetic material), present in the egg and

als). Durometer hardness is used for materials such

sperm cells of animals and in the egg and pollen cells

as rubber and plastics.

of plants. Human beings have 23 chromosomes in

their reproductive cells.

hardwood. In papermaking terminology, the

See: Diploid.

wood from deciduous trees (maple, oak, birch), re-

gardless of whether it is actually hard or soft.

haploid-diploid life cycle. Occurs when a

Use: Components of paper pulp, but in much lower

multicellular diploid phase, or sporophyte, alter-

volume than softwoods.

nates with a multicellular haploid phase, or gameto-

phyte. Only plants and certain algae possess this

Hardy-Weinberg Law. The concept that both

kind of life cycle, which is also called “alternation of

gene frequencies and genotype frequencies will re-

generations”.

main constant from generation to generation in an

infinitely large, interbreeding population in which

haploid life cycle. Occurs when the only mul- mating is at random and there is no selection, migra-

ticellular stage in an organism’s life cycle is haploid. tion or mutation.

632“HARD WATER/ACID”

“Hard Water/Acid Tolerant Synthetic Use: Fabrication into all types of process equipment.

Lube” [Ace]. TM for a conveyor lubricant.

Hauptman, Herbert A. (1917– ). An Ameri-

Hargreaves process. The manufacture of sodi-

can biophysicist who won the Nobel Prize for chem-

um sulfate (salt cake) from sodium chloride and

istry in 1985 along with Karle. Work involved de-

sulfur dioxide. A mixture of sulfur dioxide and air is

veloping equations that allow determination of

passed over briquettes of sodium chloride in a coun-

phase information from X ray crystallography inten-

tercurrent manner to produce sodium sulfate and

sity patterns. The use of computers permitted use of

hydrogen chloride. This process accounts for only a

the equations to determine the conformation of thou-

small amount of the salt cake produced in the U.S.

sands of chemicals. Hauptman was director of re-

search and vice president of the Medical Foundation

Harries ozonide reaction. Treatment of ole-

of Buffalo and a professor of biophysics in Buffalo

fins with ozone as a method of cleaving olefinic

at the State University of New York.

linkages. On hydrolysis or catalytic hydrogenation,

the initially formed ozonide yields two molecules of

“Haveg” [Ametek]. TM for a series of molding

carbonyl compounds.

compounds fabricated into corrosive-resistant

chemical process equipment. Composites of various

“Hartex” [Firestone]. TM for natural rubber

synthetic polymers with silicate fillers.

latex.

Use: Tanks, towers, scrubbers, agitators, piping, etc.

Use: Dipped goods and adhesives.

in the handling of sulfuric, hydrochloric, and phos-

phoric acids and chlorinated solvents. Also used as

hartshorn. See ammonium carbonate.

ablative products to protect metal surfaces from heat

of launching missiles.

hartshorn oil. See bone oil.

“Havelast” [Ametek]. TM for an elastomeric

HAS. Abbreviation for hydroxylamine acid sul-

binder or impregnant for various reinforcing materi-

fate.

als such as “Siltemp,” as fabric or rovings, asbestos,

glass, or graphite.

hashish. Extract of cannabis (marijuana), more

Use: Rocket and missile industry when resiliency is

concentrated and thus more powerful than the base

desired.

drug.

See cannabis.

Haworth methylation. Formation of methyl-

ated methyl glycosides from monosaccharides with

Hass chlorination rules. A series of rules

dimethyl sulfate and 30% sodium hydroxide. The

pertaining to the chlorination of saturated hydro-

glycosidic methyl group is hydrolyzed with acid to

carbons.

yield the free methylated sugar.

Hassel, Odd. (1897–1981). A Norwegian

Haworth perspective formulas. A method

chemist who won the Nobel Prize for chemistry in

for representing cyclic chemical structures (sugars)

1969 with Barton. A great deal of his work was

in order to define the configuration around each

concerned with using X ray and electron differentia-

chiral center.

tion methods of crystal and molecular structures. He

also researched stereochemistry and conformational

Haworth phenanthrene synthesis. Acyla-

analysis. His education and teaching career were in

tion of aromatic compounds with aliphatic dibasic

his homeland.

acid anhydrides to ␤-aroylpropionic acids, reduc-

tion of the carbonyl group according to Clemmensen

hassium. Hs. A transfermium element. Atomic

or Wolff-Kishner procedures, cyclization of the ␥-

number 108. Very short half-life.

arylbutyric acid with 85% sulfuric acid, and conver-

sion of the cyclic ketone to polycyclic hydroaromat-

Hass vapor-phase nitrogen. Production of

ic and subsequently to aromatic compounds.

nitroparaffins by vapor phase reaction of aliphatic

hydrocarbons with gaseous nitric acid at 420C; a

series of thirteen rules governing these reactions.

Haworth, Sir Walter N. (1883–1950). An

English chemist who received the Nobel Prize in

“Hastelloy” [Haynes]. TM for a family of chemistry in 1937 along with Paul Karrer. He rec-

high-strength, nickel-based alloys with a high resis- ommended the name ascorbic acid and synthesized

tance to uniform corrosion, outstanding resistance to vitamin C. He accomplished much work on carbo-

localized attack, and excellent stress corrosion hydrate structure and developed a substitute for

cracking resistance while maintaining ease of weld- blood plasma using carbohydrates. During World

ing and fabrication. War II, he developed gaseous diffusion separation

Available forms: Sheet, plate, bars, rods, welding on uranium isotopes. He received his Ph.D. in Man-

electrodes, and wire. chester.

633 HEAT

Hayashi rearrangement. Rearrangement of Hb. Abbreviation for hemoglobin.

␣-benzoylbenzoic acids in the presence of sulfuric

acid or phosphorus pentoxide.

HCCH. Abbreviation for hexachlorocyclo-

hexane.

“Haynes” [Haynes]. TM for a series of high-

HCE. See epoxyheptachlor.

temperature nickel and cobalt-based alloys designed

to resist high-temperature corrosion processes up to

HCG. Abbreviation for human chorionic gonado-

2200° F. Engineered to provide high temperature

tropin.

strength, resistance to creep, oxidation and sulfida-

tion resistance while maintaining ease of welding

“HCR” [Dow]. TM applied to ion-exchange

and fabrication.

resin used in water-treating and chemical process

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

applications; strong acid cation-exchange resin, 8%

electrodes, and wire.

divinylbenzene cross-linked.

Use: Fabrication into all types of process equipment.

HDPE. Abbreviation for high-density polyeth-

“Haystellite” [Cabot]. TM for tungsten car-

ylene.

bide products, principally in the form of hard-sur-

facing rods for protecting parts from severe abra-

He. Symbol for helium.

sion.

HEA. Abbreviation for 2-hydroxyethyl acrylate.

hazardous material. Any material or sub-

stance that in normal use can be damaging to the

head box. A large container, holding the pre-

health and well-being of humans. Such materials

pared slurry of paper pulp and additives, located at

cover a broad range of types that may be classified as

the head of the fourdrinier machine; the slurry is fed

follows: (1) Toxic agents (see poison; toxicity) in-

continuously from slots in the bottom of the box to

cluding drugs, chemicals, and natural or synthetic

the wire on which the sheet is formed.

products that in normal use are in any way harmful,

ranging from poisons to skin irritants and allergens.

head space. A term used in the canning industry

When improperly used, all materials can be hazard-

to refer to the space intentionally left between the

ous to humans.

top of the filled liquid and the cover of the can to

(2) Corrosive chemicals such as sodium hydroxide

allow for expansion of the contents during heat pro-

or sulfuric acid that destroy or otherwise damage the

cessing.

skin and mucous membranes on external contact or

inhalation.

“Healthya Water” [Kao]. TM for first sport

(3) Flammable materials including (a) organic sol-

drink approved as a food for specific health use.

vents, (b) finely divided metals or powders, (c) some

classes of fibers, textiles, or plastics, and (d) chemi-

heat. A form of energy associated with and pro-

cals that either evolve or absorb oxygen during stor-

portional to molecular motion. It can be transferred

age, thus constituting a fire risk in contact with

from one body to another by radiation, conduction,

organic materials.

or convection; unlike latent heat, sensible heat is

(4) Explosives and strong oxidizers such as perox-

accompanied by a change in temperature.

ides and nitrates.

—of combustion: The heat evolved when a definite

(5) Materials in which dangerous heat buildup oc-

quantity of a substance is completely oxidized

curs on storage, either by oxidation or microbiologi-

(burned).

cal action. Examples are fish meal, wet cellulosics,

—of crystallization: The heat evolved or absorbed

and other organic waste materials.

when a crystal forms from a saturated solution of a

(6) Radioactive chemicals that emit ionizing radia-

substance;

tion. Packaging, labeling, and shipping of hazardous

—of dilution: The heat evolved per mole of solute

materials by rail, highway, water, and air are regulat-

when a solution is diluted from one specific concen-

ed in the U.S. by the Department of Transportation

tration to another.

(DOT). In general, its regulations for air shipment

—of formation: The heat evolved or absorbed when

follow those of the International Air Transport As-

a compound is formed in its standard state from

sociation (IATA), though there are numerous points

elements in their standard states at a specified tem-

of difference.

perature and pressure.

An authoritative guide to the safety labeling of haz-

—of fusion: The heat required to convert a substance

ardous materials and products is issued by the Amer-

from the solid to the liquid state with no temperature

ican National Standards Institute. See toxicity;

change (also called latent heat of fusion or melting).

flammable material; label.

—of hydration: The heat associated with the hydra-

tion or solvation of ions in solution; also the heat

hazardous waste. See chemical waste; ra- evolved or absorbed when a hydrate of a compound

dioactive waste. is formed.

634HEAT EXCHANGER

—of reaction: The heat evolved or absorbed when a

heavy metal. A metal of atomic weight greater

chemical reaction occurs in which the final state of than sodium (23) that forms soaps on reaction with

the system is brought to the same temperature and fatty acids, e.g., aluminum, lead, cobalt.

pressure as that of the initial state of the reacting See soap (2).

system.

—of solution: The heat evolved or absorbed when a

heavy oil. An oil distilled from coal tar between

susbtance is dissolved in a solvent.

230C and 330C, the exact range not at all definite.

—of sublimation: The heat required to convert a unit

See coal tar.

mass of a substance from the solid to the vapor state

(sublimation) at a specified temperature and pres-

heavy oxygen. See oxygen-18.

sure without the appearance of the liquid state.

—of transition: The heat evolved or absorbed when

heavy spar. See barite.

a unit mass of a given substance is convereted from

one crystalline form to another.

heavy water. (deuterium oxide; DOD; tritium

—of vaporization: The heat required to convert a

oxide; TOT). Water composed of two atoms of

substance from the liquid to the gaseous state with

deuterium and one atom of oxygen; or one or two

no temperature change (also called latent heat of

atoms of tritium and one of oxygen. In lower states

vaporization).

of purity, the proportion of heavy water molecules

decreases. Deuterium oxide is present to the extent

heat exchanger. A vessel in which an outgoing

of approximately one part in 6500 of ordinary water.

hot liquid or vapor transfers a large part of its heat to

Deuterium oxide freezes at 3.8C, boils at 101.4C,

an incoming cool liquid; in the case of vapors, the

and has density of 1.1056 at (25C).

latent heat of condensation is thus utilized to heat the

Derivation: There are several methods of separating

entering liquid. The shell-and-tube type is widely

or concentrating DOD: (1) fractional distillation, (2)

used; here the hot liquid or vapor is contained in the

Girdler-Spevack process, (3) hydrogen-sulfide ex-

shell while the cool liquid passes through the tubes,

change process, (4) electrolysis, (5) cryogenic meth-

which are usually arranged in coils for maximum

ane distillation.

contact with the heat source. Heat exchangers are

Available forms: DOD 99.75% pure, in up to 5000 g

used in many chemical operations, e.g., evaporation

lots.

and pulp manufacture, as well as to produce steam

Use: Moderator in some types of nuclear reactors.

from the heat developed in nuclear reactors for pow-

Tritium (hydrogen of atomic weight 3) combines

er generation.

with oxygen to give another variety of heavy water,

See evaporation; heat transfer.

TOT, i.e., tritium oxide.

See tritium.

heat transfer. Transmission of thermal energy

from one location to another by means of a tempera-

ture gradient existing between the two locations. It

HEBP. See 2-hydroxyethyl dibutyl phosphate.

may take place by conduction, convection, or radia-

tion. Heat transfer is involved in many types of

hecto-. (h). Prefix meaning 10

units, e.g., 1 hg

industrial operations, including distillation, evapo-

1 hectogram

100 grams.

ration, canning of foods, baking, curing, etc. In some

cases, a heat exchanger is utilized. Fluids of high

hectorite. (hector clay).

heat capacity are widely used to remove unwanted

0.67

(Mg,Li)

(OH,F)

. One of the montmoril-

heat or to transfer it from one place to another within

lonite group of minerals that are principal constitu-

a system; examples are air, water, ethylene glycol.

ents of bentonite.

See coolant.

Hazard: Respiratory irritant.

Use: Chill-proofing of beer.

heavy. A nontechnical word used in a number of

scientific senses: (1) referring to atomic weight

hedeoma oil. See pennyroyal oil.

(heavy water, heavy metal); (2) referring to produc-

tion volume (heavy chemical); (3) referring to phys-

hedonal. (methylpropylcarbinolurethane).

ical weight (heavy spar); (4) referring to thickness

CAS: 120-36-5. CH

CH(CH

)OCONH

(heavy-gauge wire); (5) referring to distillation

Properties: White, crystalline powder; faint aromat-

range (heavy oil).

ic odor and taste. Fusing p 76C, bp 215C. Soluble in

alcohol, ether, organic solvents; sparingly soluble in

heavy chemicals. A chemical produced in ton-

cold water; more soluble in hot water.

nage quantities, often in a relatively impure state.

Use: Medicine (sedative).

Examples are sodium chloride, sulfuric acid, soda

ash, salt cake, sodium hydroxide, etc.

See basic chemicals; fine chemical.

␣-hederine.

CAS: 27013-91-8. mf: C

heavy hydrogen. See deuterium; tritium. Hazard: Low toxicity by ingestion.

635 HELLEBRIGENIN

HEDTA. See ing. All ingredients conform to FDA requirements

hydroxyethylethylenediaminetriacetic acid. for food packaging.

HEED. Abbreviation for high-energy electron

“Heliozone” [Du Pont]. TM for a blend of

diffraction.

waxy material.

Use: Retards sun-checking and cracking of rubbers.

Heeger, Alan J. (1923– ). Awarded Nobel

Prize in chemistry in 2000 jointly with Alan

helium.

G.MacDiarmid and Hideki Shirakawa for the dis-

CAS: 7440-59-7. He. Noble element of atomic num-

covery and development of conductive polymers.

ber 2, first element in the noble gas group of the

He performs his research at Texas Instruments, Dal-

periodic table, aw 4.00260, valence of 0. Helium

las, Texas.

nuclei are alpha particles. Most important isotope is

helium-3.

Hehner number. The percentage of weight of

Properties: Colorless, noncombustible gas; odorless

water-insoluble fatty acids in oils and fats.

and tasteless. Liquefies at 4.2K to form helium I; at

2.2K there is a transition (␭) point at which helium II

Heisenberg, Werner P. (1901–1976). A na-

is formed. See note below.

tive of Germany, Heisenberg received his doctorate

Properties: Bp −268.9C (1 atm), fp −272.2C (25

from the University of Munich in 1923, after which

atm) lowest of any substance, bulk d 0.1785 g/L

he was closely associated for several years with

(0C). Very slightly soluble in water; insoluble in

Niels Bohr in Copenhagen. He was awarded the

alcohol; rate of diffusion through solids is three

Nobel Prize in physics in 1932 for his brilliant work

times that of air; an asphyxiant gas.

in quantum mechanics. In 1946, he became director

See noble gas.

of the Max Planck Institute. His notable contribu-

Occurrence: Texas, Oklahoma, Kansas, New Mexi-

tions to theoretical physics, best known of which

co, Arizona, Canada. Originally discovered in the

was the uncertainty principle, imparted new impetus

sun’s atmosphere (1868) and confirmed in the atmo-

to nuclear physics and made possible a better under-

sphere of Jupiter.

standing of atomic structure and chemical bonding.

Derivation: From natural gas, by liquefaction of all

See uncertainty principle.

other components, followed by purification over

activated charcoal.

helenine. A nucleoprotein derived from the mold

Grade: USP, technical, 99.995% pure.

Penicillium funiculosum.

Use: To pressurize rocket fuels, welding, inert atmo-

Use: An antiviral drug.

sphere (growing germanium and silicon crystals),

inflation of weather and research balloons, heat-

Helferich method. Glycosidation of an acety-

transfer medium, leak detection, chromatography,

lated sugar by heating with a phenol in the presence

cryogenic research, magnetohydrodynamics, lumi-

of zinc chloride or p-toluenesulfonic acid as cata-

nous signs, geological dating, aerodynamic re-

lyst.

search, lasers, diving and space-vehicle breathing

equipment. Possible future uses include coolant for

Helianthine B. See methyl orange.

nuclear fusion power plants and in superconducting

electric systems.

helicase. An enzyme that catalyzes the unwind-

Note: Liquid helium has unique thermodynamic

ing of strands in a DNA molecule before replication.

properties too complex to be adequately described

here. Liquid He I has refr index 1.026, d 0.125, and is

“Helindon” [BASF]. TM for vat dyestuffs

called a “quantum fluid” because it exhibits atomic

used for dyeing wool.

properties on a macroscopic scale. Its bp is near

absolute zero and viscosity is 25 micropoises (water

“Heliogen” [BASF]. TM for phthalocyanine

10,000). He II, formed on cooling He I below its

dyestuffs.

transition point, has the unusual property of super-

Use: Paint, lacquers, printing inks, wallpaper, coated

fluidity, extremely high thermal conductivity, and

paper, rubber, and plastics.

viscosity approaching zero.

See superconductivity.

“Helisorb” [Norquay]. TM for UV stabilizer.

Properties: Free-flowing nonhazardous powder.

helix-loop-helix. A protein structural motif

Use: An effective UV stabilizer for UVA and UVB

characteristic of certain DNA-binding proteins.

protection in low concentrations for cosmetics and

plastics.

hellebrigenin 3-acetate.

“He-Li-Ox” 500 Series [Mallinckrodt]. CAS: 4064-09-9. mf: C

TM for a series of PVC heat stabilizers for extrud- Hazard: A poison.

ing, injection molding, calendering, and blow mold- Source: Natural product.

636HELL-VOLHARD-ZELINSKY

Hell-Volhard-Zelinsky reaction. ␣-Haloge- sorbed by cancerous tissues, making them fluoresce

under UV light.

nation of carboxylic acids with halogen and phos-

Use: Medicine (antidepressant).

phorus, presumably involving the enol form of the

intermediate acyl halide.

hematoxylin.

17-␣-helveticoside.

CAS: 517-28-2. C

•3H

CAS: 6869-17-6. mf: C

Properties: Slightly yellow crystals, turning red in

Hazard: A poison.

light. Mp 100–120C. Soluble in hot water and alco-

Source: Natural product.

hol, in glycerol, and in alkali hydroxides.

Hazard: May be carcinogenic.

hem-. Prefix indicating relationship to blood.

Use: Colorant in inks, biological stains.

HEMA. See hydroxyethyl methacrylate.

heme. (hem). C

FeN

. The nonprotein por-

tion of hemoglobin and myoglobin, consisting of

hema-. Prefix indicating relationship to blood.

reduced (ferrous) iron bound to protoporphyrin.

See porphyrin hemin.

hematein.

Use: Medical and biochemical research.

CAS: 475-25-2. C

. A tetracyclic compound.

An oxidation product of hematoxylin, the coloring

hemel. (generic name for hexamethylmela-

principle of logwood. Not to be confused with he-

mine; HMM). C

[N(CH

)

]

(cyclic).

matin.

Properties: Solid. Insoluble in water; soluble in ace-

Properties: Dark-purple solid. Mp 200+C. Almost

tone.

insoluble in water, slightly soluble in alcohol and

Use: Chemosterilant for insects.

ether; soluble in dilute sodium hydroxide, giving a

bright-red color; soluble in ammonia with brown-

hemellitic acid. (2,3-xylic acid).

ish-violet color.

(CH

)

COOH.

Derivation: By adding ammonia to logwood extract

Properties: Mp 144C.

and exposing to air.

Use: Indicator, biological stain.

hemi-. Prefix meaning half.

hematin. C

FeOH. The hydroxide of

heme. Not to be confused with hematein.

hemicellulose. Cellulose having a degree of po-

Properties: Blue to brown-black powder. Decom-

lymerization of 150 or less. A collective term for ␣

poses at 200C without melting. Soluble in alkalies,

and ␥ cellulose. It is that portion of holocellulose

hot alcohol, or ammonia; slightly soluble in hot

that is soluble in mild caustic solution. The pure

pyridine; insoluble in water, ether, and chloroform.

form is obtained from corn grain hulls. It is not an

Derivation: By dissolving hemin in dilute potassium

important component of cellulosic products and is of

hydroxide, precipitating with acetic acid, and re-

chiefly theoretical interest. Hemicellulose obtained

crystallizing from pyridine.

by treating a mixture of hard and softwoods with

Use: Biochemical research.

steam has been used as an animal feed supplement.

hematite, red. (red iron ore; bloodstone; iron

hemicholinium.

oxide).

CAS: 16478-59-4. mf: C

CAS: 1317-60-8. Fe

with impurities.

Hazard: A poison by ingestion.

Properties: Brilliant black to blackish-red or brick-

red mineral with brown to cherry-red streak and

hemiketal. Organic compound formed by the

metallic to dull luster. D 4.9–5.3, Mohs hardness 6.

reaction of one molecule of ketone (RR

′

CO) with

Noncombustible.

one molecule of alcohol (R

′′

CO). Hemiketals are the

Hazard: A carcinogen (OSHA).

rings of ketose sugars.

Use: The most important ore of iron. Also certain

See ketals.

varieties are used as paint pigments and for rouge.

See iron oxide reds; ferric oxide.

hemimellitene. (1,2,3-trimethylbenzene).

(CH

)

hemato-. Prefix indicating relationship to blood.

Properties: Liquid. D 0.8944 (20/4C), fp −25.5C, bp

176C. Insoluble in water; soluble in alcohol. Occurs

hematoporphyrin.

in some petroleums.

CAS: 14459-29-1. C

. Deep-red crystals;

Hazard: Combustible. TLV: 25 ppm.

soluble in alcohol, sparingly soluble in ether; insolu-

Use: Raw material for chemical synthesis.

ble in water.

Derivation: Obtained from hemin or hematin by the

action of strong acids.

hemin. (Teichmann’s crystals; the chloride of

Hazard: Toxic. Reported to be preferentially ab- heme). C

FeCl.

δHHb

COOH

637 HENNA

hempa. (generic name for hexamethylphos-

phoric triamide; hexamethylphosphoramide;

HMPA; hexametapol).

CAS: 680-31-9. [N(CH

)

]

PO.

Properties: Water-white liquid; mild amine odor. Bp

230–232C (739.4 mm Hg), d 1.021 (15.5/15.5C).

Soluble in water and polar and nonpolar solvents.

Hazard: TLV: animal carcinogen. Toxic by skin

contact. Combustible.

Use: UV inhibitor in polyvinyl chloride, chemosteri-

lant for insects, promoting stereospecific reactions,

specialty solvent.

hempseed oil.

Properties: A drying oil similar in properties and

uses to linseed. Edible, iodine value approximately

Properties: Crystals that are brown by transmitted

160, d 0.923, refr index 1.470–1.472. Contains ap-

light and steel blue by reflected light. Sinters at

proximately 10% saturated fatty acids (palmitic and

240C. Freely soluble in ammonia water; soluble in

stearic), unsaturated acids present are linoleic, lin-

strong organic bases; insoluble in carbonate solu-

olenic, and oleic. Saponification value 190−193.

tions, dilute acid solutions; insoluble but stable in

Source: Produced chiefly in the former U.S.S.R.,

water.

southern Europe, Japan, Chile, little in U.S.

Derivation: By heating hemoglobin with acetic acid

Hazard: Combustible.

and sodium chloride.

Use: Identification of blood stains, biochemical re-

henda- compounds. See unde-.

search, complexing agent.

See chelate.

Henderson-Hasselbalch equation. An

equation relating the pH, the pKa, and the ratio of the

hemizygous. Having only one copy of a particu-

concentrations of the proton-acceptor (A-) and pro-

lar gene. For example, in humans, males are hemizy-

ton-donor (HA) species in a solution.

gous for genes found on the Y chromosome.

n-heneicosanoic acid. CH

(CH

)

COOH. A

hemo-. (haemo-, hem-, hema-, hemato-). Pre-

saturated fatty acid not normally found in natural

fix indicating relationship to blood.

fats or waxes.

Properties: White, crystalline solid. Mp 74.3C. Syn-

hemoglobin. (Hb). The respiratory protein of

thetic product available for organic synthesis, 99%

the red blood cells, it transfers oxygen from the

purity.

lungs to the tissues and carbon dioxide from the

Hazard: Combustible.

tissues to the lungs. Its affinity for carbon monoxide

is greater than 200 times that for oxygen. Hemoglo-

(z)-6-1-heneicosen-11-one.

bin is a conjugated protein of molecular weight

CAS: 54844-65-4. mf: C

65,000, consisting of approximately 94% globin

Hazard: Low toxicity by ingestion and skin contact.

(protein portion) and 6% heme. Each molecule can

Source: Natural product.

combine with one molecule of oxygen to form oxy-

hemoglobin (HbO

). The iron (in the heme portion)

henequen.

must be in the reduced (ferrous) state to enable the

Properties: Hard, strong, reddish fibers obtained

hemoglobin to combine with oxygen. Oxyhemoglo-

from the leaves of Agave fourcroydes. It is similar to

bin is available commercially as a brownish-red

sisal but coarser and stiffer.

powder or crystals, soluble in water.

Available forms: Denier ranges from 300 to 500.

Use: Medicine, usually called hemoglobin.

Source: Mexico, Cuba.

Hazard: Combustible.

hemp. Soft, white fibers 3–6 ft long. It is coarser

Use: Binder twine, cordage.

than flax but stronger, more glossy, and more dura-

ble than cotton. Obtained from the stems of Canna-

Henkel reaction. Industrial-scale thermal rear-

bis sativa.

rangement or disproportionation of alkaline salts of

Source: Central Asia, Italy, the former U.S.S.R.,

aromatic acids to symmetrical diacids in the pres-

India, U.S.

ence of cadmium or other metallic salts.

Hazard: Combustible. May ignite spontaneously

when wet.

Use: Blended with cotton or flax in toweling and

henna. A coloring principle obtained from dried

heavy fabrics, twine, cordage, packing. leaves of certain tropical plants (North Africa,

See cannabis. India).

638“HENNIG PURIFIER”

Use: Commercial hair-dyeing preparations to give a

hepatocyte. The major cell type of liver tissue,

yellow-red color; medicine as an antifungal agent. which is parenchymal tissue. Liver also contains

fixed macrophages called Kupfer cells and other

cells.

“Hennig Purifier” [PPG]. TM for a prepara-

tion having a soda-ash base and other materials.

Produced as walnut-sized briquettes. Packed in 100-

hepatoxane. See hepasynthyl.

lb paper bags.

Use: Ladle addition to produce cleaner steel by aiding

“Hepsera Tabs” [Lapgap]. TM for tablets.

in removal of dissolved oxides and silicates and

Use: For antiviral treatment of chronic hepatitis B.

fluxing nonmetallic inclusions to slag.

heptabarbital. (5-[1-cyclohepten-1-yl]-5-ethyl-

Henry reaction. Formation of nitroalcohols by

barbituric acid; 5-ethyl-5-cycloheptenylbarbituric

an aldol-type condensation of nitroparaffins with

acid).

aldehydes in the presence of base (Henry) or by the

CAS: 509-86-4. C

condensation of sodium salts of acinitroparaffins

Properties: White, crystalline powder; odorless;

with the sodium bisulfite addition products of alde-

slightly bitter taste. Mp 174C. Very sparingly solu-

hydes in the presence of a trace of alkali or weak acid

ble in water; slightly soluble in alcohol; soluble in

(Kamlet). Widely used in sugar chemistry.

alkaline solutions. Forms water-soluble sodium,

magnesium, and calcium salts.

Henry’s law. When a liquid and a gas are in

Use: Medicine (sedative).

contact, the mass of the gas that dissolves in a given

See barbiturate.

quantity of liquid is proportional to the pressure of

the gas above the liquid. Thus, if air is kept in contact

heptachlor. (generic name for 1, 4, 5, 6, 7,

with water at standard atmospheric pressure, each

8, 8-heptachloro-3a,4,7,7a-tetrahydro-4,7-metha-

kg of water dissolves 0.017 g oxygen at 20C; if this

noindene. Generic).

pressure is halved (by doing the experiment at high

CAS: 76-44-8. C

altitude where the pressure is only 0.5 atm), the

Properties: White to light-tan, waxy solid. Mp

water dissolves only 0.0085 g oxygen. The law

95–96C, d 1.57–1.59. Insoluble in water; soluble in

holds true only for equilibrium conditions, i.e., when

xylene and alcohol.

enough time has elapsed so that the quantity of gas

Hazard: Toxic by ingestion, inhalation, and skin

dissolved is no longer changing.

absorption; use has been restricted and discontinued

except for termite control. TLV: 0.5 mg/m

; animal

hentriacontane. C

or CH

(CH

)

carcinogen.

Properties: Crystals. D 0.781 (68C), bp 302C (15

Use: Insecticide.

mm Hg), mp 68C.

Hazard: Combustible.

heptachlorepoxide. C

O. A degradation

product of heptachlor that also acts as an insecticide.

HEOD. See dieldrin.

See epoxyheptachlor.

heparin.

heptachlorotetrahydromethanoindene.

CAS: 9005-49-6. A complex organic acid (muco-

See heptachlor.

polysaccharide) present in mammalian tissues; a

strong inhibitor of blood coagulation; a dextrorota-

n-heptacosane. CH

(CH

)

tory polysaccharide built up from hexosamine and

Properties: Crystals. D 0.804, bp 270C (15 mm Hg),

hexuronic acid units containing sulfuric acid ester

mp 59.5C. Soluble in alcohol; insoluble in water.

groups. Precise chemical formula and structure unc-

Hazard: Combustible.

ertain; a formula of (C

)

and molecular

weight of 12,000 have been suggested for sodium

n-heptadecane. C

or CH

(CH

)

heparinate.

Properties: Leaflets, soluble in alcohol. D 0.778, bp

Properties: White or pale-colored amorphous pow-

303C, mp 22.5C. Insoluble in water.

der; nearly odorless; hygroscopic. Soluble in water;

Hazard: Combustible.

insoluble in alcohol, benzene, acetone, chloroform,

and ether; pH in 17% solution between 5.0 and 7.5.

Derivation: Animal livers or lungs.

n-heptadecanoic acid. (margaric acid).

Grade: USP.

CAS: 506-12-7. CH

(CH

)

COOH. A saturated fat-

Hazard: May cause internal bleeding.

ty acid not normally found in natural fats or waxes.

Use: Medicine (anticoagulant), biochemical re-

Properties: Colorless crystals. Mp 61C, d 0.8355

search, rodenticides.

(90.6/4C), bp 363.8C, 230.7C (16 mm Hg), refr

index 1.4324 (70C). Soluble in alcohol and ether;

hepasynthyl. insoluble in water.

CAS: 5634-42-4. mf: C

•C

. Available forms: 99% pure synthetic product.

Hazard: Moderately toxic by ingestion. Use: Organic synthesis.

639

-HEPTANOIC ACID

heptadecanol. Any saturated C

alcohol. heptalin acetate. See methylcyclohexanol ac-

Hazard: Combustible. etate.

See n-heptadecanol; 3,9-diethyl-6-tridecanol.

heptamethylene. See cycloheptane.

n-heptadecanol. C

OH.

Properties: Colorless liquid. D 0.8475 (20/20C), bp

heptamethylnonane. C

. Isomer of cetane

308.5C, vap press <0.01 mm Hg (20C), flash p 310F

(hexadecane). In 1964 it replaced ␣-methylna-

(154C), bulk d 7.1 lb/gal (20C). Slightly soluble in

phthalene as ignition standard for diesel fuels.

water.

Properties: Ignition value 15 on cetane-␣-methylna-

Grade: Technical.

phthalene scale.

Hazard: Combustible.

Hazard: Flammable, moderate fire risk.

Use: Organic synthesis, plasticizer, intermediates,

perfume fixatives, soaps and cosmetics, manufac-

heptanal. (heptaldehyde; enanthaldehyde; al-

ture of wetting agents and detergents.

dehyde C-7).

CAS: 111-71-7. C

CHO.

2-(8-heptadecenyl)-2-imidazoline-1-ethanol.

Properties: Oily, colorless liquid; penetrating, fruity

See amine 220.

odor; hygroscopic. D 0.814–0.819, refr index 1.42,

mp 43C, bp 153C. Soluble in three volumes of 60%

2-heptadecylglyoxalidine. (2-heptadecylimi-

alcohol, slightly soluble in water. Soluble in ether.

dazoline). C

or C

Derivation: Castor oil, from decomposition of the

Properties: Waxy solid. Mp 85C, bp 200C (2 mm

ricinoleic acid glyceride.

Hg). Slightly soluble in water; soluble in alcohol,

Hazard: Combustible.

benzene; hydrolyzes on standing to form N-2-ami-

Use: Manufacture of 1-heptanol, organic synthesis,

noethyl stearamide.

perfumery, pharmaceuticals, flavoring.

Derivation: By reacting stearic acid with ethylene

diamine.

n-heptane. (dipropylmethane).

Hazard: Combustible.

CAS: 142-82-5. CH

(CH

)

Use: Fungicide.

Properties: Volatile, colorless liquid. Fp −90.595C,

bp 98.428C, refr index 1.38764 (20C), d 0.68368

2-heptadecylglyoxalidine acetate. See

(20C), flash p 25F (−3.89C) (CC). Soluble in alco-

glyodin.

hol, ether, chloroform; insoluble in water; distilla-

tion range 93.3–98.9C; vap press 2.0 psi (a)(37.7C)

2-heptadecylimidazoline. See 2-heptadecyl-

(max). Color Saybolt +30 (min), maximum sulfur

glyoxalidine.

content 0.01 wt %, corrosive passes ASTM D

130–30 test, autoign temp 433F (222C).

2-heptadecyl-2-imidazoline acetate. See

Derivation: Fractional distillation of petroleum, pu-

glyodin.

rified by rectification.

Grade: Commercial, 99%, spectro, ASTM reference

heptafluorobutyric acid. (perfluorobutyric

fuel, research, 99.92 mole %.

acid). C

COOH.

Hazard: Toxic by inhalation. Flammable, dangerous

Properties: Colorless, hygroscopic liquid with sharp

fire risk. TLV: TWA 400 ppm; STEL 500 ppm.

odor. Bp 120C (735 mm Hg), fp −17.5C, d 1.641

Use: Standard for octane-rating determinations (pure

(25C), refr index 1.290 (25C), surface tension 15.8

normal heptane has zero octane number), anesthetic,

dynes/cm (30C). Miscible with water, acetone,

solvent, organic synthesis, preparation of laboratory

ether, and petroleum ether; soluble in benzene and

reagents.

carbon tetrachloride; insoluble in carbon disulfide

See octane number.

and mineral oil.

Derivation: By electrolysis of a solution of butyric

1,7-heptanedicarboxylic acid. See azelaic

acid in hydrogen fluoride.

acid.

Hazard: Irritant to tissue.

Use: Intermediate, surfactant, acidulant.

1,7-heptanedioic acid. See pimelic acid.

␥-heptalactone.

CAS: 105-21-5. mf: C

n-heptanoic acid. (enanthic acid; n-heptylic

Properties: Colorless, sltly oily liquid; coconut,

acid; heptoic acid).

sweet, malty, caramel odor. D: 0.997−1.004 @ 20°,

CAS: 111-14-8. CH

(CH

)

COOH.

refr index: 1.439−1.445. Misc in alc, fixed oils; very

Properties: Clear, oily liquid; unpleasant odor. D

sltly sol in water.

0.9181 (20/4C), fp 8C, bp 221.9C, refr index 1.4229.

Hazard: A skin irritant.

Soluble in alcohol and ether, insoluble in water.

Use: Food additive;.

Derivation: By oxidizing heptanal with potassium

permanganate in dilute sulfuric acid.

heptaldehyde. See heptanal. Hazard: Combustible.

6401-HEPTANOL

Use: Organic synthesis, production of special lubri-

1-heptyl acetate.

cants for aircraft and brake fluids. CAS: 112-06-1. C

OOCCH

. Liquid with fruity

odor.

Use: Artificial fruit essences.

1-heptanol. See heptyl alcohol.

heptyl alcohol. (1-heptanol; enanthyl alco-

2-heptanol. See methyl amyl carbinol.

hol).

CAS: 111-70-6. C

OH.

3-heptanol.

Properties: Colorless, fragrant liquid. Fp −34.6C, bp

CAS: 589-82-2. CH

CH(OH)C

175C, d 0.824 (20/4C), refr index 1.4233 (20C),

Properties: Liquid. D 0.8224 (20C), fp −70C, bp

flash p 170F (76.6C). Slightly soluble in water;

156.2C, flash p 140F (60C) (CC). Slightly soluble in

miscible with alcohol and ether.

water.

Derivation: From heptaldehyde by reduction.

Hazard: Toxic by ingestion. Moderate fire risk.

Hazard: Combustible.

Use: Flotation frother, solvent and diluent in organic

Use: Organic intermediate, solvent, cosmetic formu-

coatings, intermediates.

lations.

2-heptanone. See methyl-n-amyl ketone.

heptylamine. C

Properties: Colorless liquid. D 0.777 (20/4C), fp

−23C, bp 155C, flash p 140F (60C) (OC). Slightly

3-heptanone. See ethyl butyl ketone.

soluble in water; soluble in alcohol and ether.

Hazard: Combustible.

4-heptanone. See dipropyl ketone.

heptyl formate. HCOOC

heptanoyl chloride. CH

(CH

)

COCl.

Properties: Colorless liquid; fruity odor. Bp 176.7C,

Properties: Solid. Mw 148.63, bp 173C, d 0.960, fp

d 0.894 (0C).

58C.

Hazard: Combustible.

Hazard: Corrosive and a lachrymator.

Use: Artificial fruit essences.

1-heptene. (1-heptylene). CH

(CH

)

CH:CH

heptyl heptoate. C

OOCC

Properties: Colorless liquid. D 0.6968 (20/4C), bp

Properties: Colorless liquid; fruity odor. D 0.865

93.3C, fp −10C, flash p 32F (0C), refr index 1.3994

(19C), bp 273–274C (754 mm Hg).

(20C). Soluble in alcohol, acetone, ether, petroleum

Hazard: Combustible.

and coal tar solvents; insoluble in water.

Use: Artificial fruit essences.

Hazard: Flammable, dangerous fire risk.

Use: Organic synthesis.

n-heptyl p-hydroxybenzoate. See heptyl-

paraben.

2-heptene. (2-heptylene).

(CH

)

CH:CHCH

(cis and trans isomers).

n-heptylic acid. See heptanoic acid.

Properties: Colorless liquid. D (cis) 0.708, (trans)

0.704, (commercial) 0.7010–0.7050 (20/4C), bp

heptyl (4-(1-methylethyl)phenyl)methyl 3-

(trans) 98C, (cis) 98.5C, (commercial) 97–99C, refr

pyridinylcarbonimidodithioate.

index 1.406 (20C); flash p (commercial) 28F

CAS: 51308-74-8. mf: C

(−2.2C). Soluble in alcohol, acetone, ether, petrole-

Hazard: Moderately toxic by ingestion.

um, and coal tar solvents; insoluble in water.

Use: Agricultural chemical.

Hazard: Flammable, dangerous fire risk.

Use: Suggested as plant growth-retardant.

heptylparaben. mf: C

Properties: Small colorless crystals or white crystal-

3-heptene. (3-heptylene). C

CH:CHC

line powder; odorless, burning taste. Mp: 48−51°.

Properties: (Mixed cis and trans isomers) Colorless

Sol in alc, ether; very sltly sol in water.

liquid. Bp 95C, d 0.705 (15.5/15.5C), refr index

Use: Food additive.

1.405 (20C), flash p 21F (−6.1C).

Hazard: Flammable, dangerous fire risk.

heptyl pelargonate. C

OOCC

Use: Suggested as plant-growth retardant.

Properties: Liquid with pleasant odor. D 0.866

(15.5/15.5C), bp 300C, refr index 1.4360.

6-heptenoic acid, 7-(2-cyclopropyl-4-(4-

Hazard: Combustible.

fluorophenyl)-3-quinolinyl)-3,5-dihydroxy-

Use: Flavors and perfumes.

,calcium salt (2:1), (3r,5s,6e)-. See NK

104 (acid).

␣-heptyl-3,4,5-trimethoxyphenethylamine.

CAS: 67293-51-0. mf: C

heptoic acid. See heptanoic acid. Hazard: A poison.

641 HERZ REACTION; HERZ

herbicide. (weed killer). A pesticide, either or- “Herculon” [Aqualon]. TM for polypropyl-

ganic or inorganic, used to destroy unwanted vege- ene olefin fibers. Available in bulked continuous

tation, especially various types of weeds, grasses, and continuous multifilament yarns, staple, and un-

cut tow.

and woody plants. Until 1924 inorganics such as

Use: Apparel, home furnishings, and industrial appli-

sodium chlorate, sodium chloride, ammonium sul-

cations.

famate, arsenic, and boron compounds were used.

At that time the more specific organics were intro-

hereditary cancer. Cancer that occurs due to

duced, typified by 2,4-dichlorophenoxyacetic acid

the inheritance of an altered gene within a family.

(2,4-D). Herbicides may be of two major types: (1)

See sporadic cancer.

selective, such as 2,4-D, 2,4,5-T, phenols, carba-

mates and urea derivatives, permitting elimination

of weeds without injury to the crop, and (2) nonse-

hereditary mutation. A gene change in the

lective, comprising soil sterilants (sodium com- body’s reproductive cells (egg or sperm) that be-

pounds) and silvicides (ammonium sulfamate). The comes incorporated in the DNA of every cell in the

latter kill woody plants and trees. Some types act as body; also called germline mutation.

overstimulating growth hormones. Many herbicides

are highly toxic and should be handled and applied

heroin. See diacetylmorphine.

with care; use of chlorinated types may be restricted.

See defoliant.

herring oil. See fish oil.

herbifert.

Herschbach, Dudley R. (1932– ). Awarded

CAS: 39324-65-7. mf: C

S•C

ClN

the Nobel Prize in chemistry in 1986 for work re-

Hazard: Moderately toxic by ingestion. Low toxicity

porting that the energies of reactions of crossed

by skin contact. SO

, and Cl

−

molecular beams of isolated alkali metal atoms and

alkyl halide molecules appeared mostly as vibra-

“Herclor” [Aqualon]. TM for a group of spe-

tional excited states of products. This method of

cialty elastomers based on epichlorohydrin, claimed

studying all types of chemical reactions led to a

to have unique service performance properties.

more detailed knowledge of reaction processes.

Use: Automotive and aircraft parts, wire and cable

Doctorate awarded from Harvard in 1958.

coating, seals and gaskets, packings, hose, belting,

and coated fabrics. “Herclor H” is a homopolymer,

Hershko, Avram. (1937– ). Born in Karcag,

and “Herclor C” a copolymer with ethylene oxide;

Hungary, Hershko won the Nobel Prize for chemis-

both have high resistance to ozone, heat, solvents,

try in 2004 for his pioneering work concerning the

and chemical attack.

discovery of ubiquitin-mediated protein degrada-

tion. He received his M.D. in 1965 and his Ph.D in

“Hercoflex” [Aqualon]. TM for a series of

1969 from the Hadassah Faculty of Medicine of the

plasticizers. 600 High-boiling ester of pentaerythri-

Hebrew University of Jerusalem. He is currently a

tol and a saturated aliphatic acid. 707 High molecu-

Distinguished Professor at the Rappaport Family

lar weight polyol ester. 707A High molecular

Institute for Research in Medical Sciences at the

weight polyol ester.

Technion (Israel Institute of Technology) in Haifa

Use: High-temperature vinyl electrical insulation.

and Adjunct Professor of Pathology at New York

900 High molecular weight polyester.

University. In 2000 he received the Albert Lasker

Use: Plasticizer for polyvinyl acetate.

Award for Basic Medical Research.

“Hercolube” [Aqualon]. TM for synthetic lu-

Herzberg, Gerhard. (1904–1999). A German-

bricant base stocks. J15 Saturated aliphatic ester of

born physicist who won the Nobel Prize for chemis-

pentaerythritol for plasticizing vinylidene chloride.

try in 1971 for his work on the composition of

Derivation: Derived from pentaerythritol esters of

molecules. His research involved the spectroscopy

saturated fatty acids.

of atoms and molecules and their excitation behav-

ior. He became a Canadian citizen and was the direc-

“Hercolyn” D [Aqualon]. TM for a pale, vis- tor of the Division of Pure Physics of the National

cous liquid; the hydrogenated methyl ester of rosin. Research Council of Canada.

Use: Plasticizing resin.

Herzig-Meyer determination of N-alkyl

hercules trap. Water-measuring liquid trap groups. N-alkylamines are refluxed with hy-

used in aquametry when the material collected is driodic acid and the quaternary alkyl ammonium

heavier than water. iodides are pyrolyzed to split off alkyl iodide, which

is determined gravimetrically by conversion to sil-

ver iodide or titrated as iodate.

“Herculoid” [Aqualon]. TM for nitrocellu-

lose containing 10.9–11.2% nitrogen.

Hazard: See nitrocellulose.

Herz reaction; Herz compounds. Forma-

Use: Pyroxylin plastics. tion of o-aminothiophenols by heating aromatic

642HESPERIDIN

amines with excess sulfur monochloride. The first DNA molecules with similar or partially identical

products formed are thiazothionium halides known sequences. Sometimes from two unmanipulated

as Herz compounds. If the position next to the amino species, at other times a gene has been modified and

reintroduced.

group is unoccupied, chloride is substituted at this

position during the reaction.

heterogeneity. The production of identical or

similar phenotypes by different genetic mecha-

hesperidin.

nisms.

CAS: 520-26-3. C

. A natural bioflavonoid of

the flavanone group.

heterogeneous. (Latin “different kinds”). Any

Properties: Fine needles. Mp 258–262C. Soluble in

mixture or solution comprised of two or more sub-

dilute alkalies and pyridine.

stances regardless of whether they are uniformly

Derivation: Extraction from citrus fruit peel.

dispersed. Common examples are such diverse ma-

Use: Synthetic sweetener research.

terials as air (a mixture of 20% oxygen and 80%

nitrogen), milk, marble, paint, gasoline, blood and

Hess’s law. The heat evolved or absorbed in a

mayonnaise. In all such cases, the mixtures can be

chemical process is the same whether the process

separated mechanically into their components. “Ho-

takes place in one or in several steps; also known as

mogenized” milk is as heterogeneous as regular

the law of constant heat summation.

milk and the term is, strictly speaking, a misnomer.

See homogeneous; mixture.

hetastarch. A starch derivative containing 90%

amylopectin.

heterogeneous catalysis. See catalysis, het-

Use: Blood plasma volume expander.

erogeneous.

heteratisine. See 20-ethyl-6-␤,8-dihydroxy-1-

heteromolybdates. (heteropolymolybdates). A

␣-methoxy-4.

large group of complex molybdenum salts and acids

in which the anion contains oxygen atoms and from

heteratisine 6-benzoate.

2 to 18 hexavalent molybdenum atoms, as well as

CAS: 99759-48-5. mf: C

one or more other metal or nonmetal atoms (phos-

Hazard: A poison.

phorus, arsenic, iron, and tellurium). The latter are

Source: Natural product.

referred to as hetero atoms, and any of approximate-

ly 35 elements may be present in this manner. Exam-

heteroaromatic. See heterocyclic.

ple: Na

PMo

, sodium phospho-12-molybdate.

The molecular weights of these compounds range up

heteroazeotrope. Azeotropic mixture having

to 3000. The acids and most of the salts are very

more than one liquid phase in equilibrium with the

soluble in water, and the acids and some salts are

vapor phase at the boiling points.

soluble in organic solvents.

Use: Phosphomolybdates and phosphotungstates are

heterochromatin. Chromatin which is in a con-

used as precipitants for basic dyes to form lakes and

densed, less accessible state and thus frequently

toners. The phospho- and silicomolybdate groups

transcriptionally silent. However, some DNA is

are of key importance in the functioning of certain

constitutive heterochromatin (e.g. the second X

enzymes. There are many uses in analytical chem-

chromosome is inactivated to a Barr body for dosage

istry.

compensation) whereas other DNA is facultative

heterochromatin. An example might be genes re-

heterophos.

quired under time of stress only, or during a stage of

CAS: 40626-35-5. mf: C

PS.

the cell cycle.

Hazard: A poison by ingestion.

Use: Agricultural chemical.

heterocyclic. Designating a closed-ring struc-

ture, usually of either 5 or 6 members, in which one

heteropolysaccharide. A polysaccharide con-

or more of the atoms in the ring is an element other

taining two or more types of sugars.

than carbon, e.g., sulfur, nitrogen, etc. Examples are

pyridine, pyrole, furan, thiophene, and purine.

heterotroph. An organism that requires complex

nutrient molecules, such as glucose, as an energy

source.

heterotropic enzyme. An allosteric enzyme

requiring a molecule other than its substrate as a

modulator.

heteroduplex DNA. Duplex DNA containing heterozygosity. The presence of different alleles

complementary strands derived from two different at one or more loci on homologous chromosomes.

643 1,2,3,4,5,6-HEXACHLOROCYCLO

heterozygote. See heterozygosity. Hazard: Toxic by ingestion and inhalation, strong

irritant. Combustible. Evolves phosgene when

heated.

HETP. (1) Abbreviation for hexaethyl tetra-

Use: Desiccant, herbicide.

phosphate; (2) abbreviation for height equivalent to

a theoretical plate.

hexachlorobenzene. (perchlorobenzene).

See theoretical plate.

CAS: 118-74-1. C

Properties: White needles. D 2.04, mp 229C, bp

“Hetron” [Ashland]. TM for an unsaturated

326C, flash p 468F (242C). Soluble in benzene and

polyester resin.

boiling alcohol; insoluble in water.

Use: Corrosion and chemical resistance, fire-retar-

Hazard: TLV: 0.002 (skin); Animal Carcinogen.

dant, castings, marine gel coats, laminating, and

Toxic by ingestion. Combustible.

molding.

Use: Organic synthesis, fungicide for seeds, wood

preservative.

Heumann-Pfleger indigo synthesis. Cycli-

zation of phenylglycine to indoxyl followed by oxi-

2,2

′

,4,4

′

,6,6

′

-hexachlorobiphenyl.

dation by air or oxidizing agents, such as ferric

CAS: 33979-03-2. mf: C

chloride, to yield indigo.

Hazard: A poison.

heuristic. See computational chemistry.

2,3

′

,4,4

′

,6-hexachlorobiphenyl.

CAS: 59291-65-5. mf: C

Hevesy, Georg de. (1885–1966). A Hungarian

Hazard: A poison.

chemist who won the Nobel Prize in chemistry in

1943. He discovered the element hafnium in 1923.

One of his interesting projects involved the calcula-

hexachlorobutadiene.

tion of the percentages of chemical elements in the

CAS: 87-68-3. Cl

C:CClCCl:CCl

universe. He also was involved in research using

Properties: Clear, colorless liquid; mild odor. Freez-

radioactive lead and phosphorus traces. His work

ing range −19 to −22C, boiling range 210–220C, refr

included the separation of isotopes by physical

index 1.552 (20C), flash p none, d 1.675 (15.5/

means. His Ph.D. was granted at Freiburg in 1908.

15.5C), bulk d 13.97 lb/gal (15.5C), purity 98%

(min). Vap press 22 mm Hg (100C), 500 mm Hg

hexa-. Prefix signifying six.

(200C). Viscosity (37.7C) 2.447 cP, 1.479 centi-

stokes; (98.9C) 1.131 cP, 0.724 centistokes. Insolu-

hexabromobenzene.

ble in water, compatible with numerous resins, solu-

CAS: 87-82-1. mf: C

ble in alcohol and ether. Nonflammable.

Hazard: A poison.

Hazard: Toxic by ingestion and inhalation, a sus-

pected carcinogen. TLV: TWA 0.02 ppm; animal

hexabromoethane. C

. carcinogen.

Properties: Yellowish-white, rhombic needles. Use: Solvent for elastomers, heat-transfer liquid,

Slightly soluble in water and alcohol. Mp 149C transformer and hydraulic fluid, wash liquor for

(decomposes with separation of bromine). removing C

and higher hydrocarbons.

Derivation: Action of bromine on diiodoacetylene.

Use: Organic synthesis.

1,2,3,4,5,6-hexachlorocyclohexane. (BHC;

HCCH; HCH; TBH; benzene hexachloride).

1,2,3,4,6,7-hexabromonaphthalene.

CAS: 608-73-1. C

. A systemic insecticide.

CAS: 75625-24-0. mf: C

The ␥ isomer is known as lindane.

Hazard: A poison by ingestion.

Properties: White or yellowish powder or flakes;

musty odor. Melting point vary with isomeric com-

1,1,1,3,3,3-hexabutyldistannthiane.

position. D 1.87, vap press approximately 0.5 mm

CAS: 4808-30-4. mf: C

SSn

Hg (60C). Stable toward moderate heat but decom-

Properties: Colorless oil. Bp: 208° (decomp).

posed by alkaline substances. Mp of the pure iso-

Hazard: Moderately toxic by ingestion. TWA 0.1

mers are (␣-trans) 157–158C, (␤-cis) 297C (sub-

mg(Sn)/m

; STEL 0.2 mg/m

(skin)

limes), (␥) 112.5C, (⌬) 138–139C, (⑀) 217–219C.

Use: Drug.

Insoluble in water; soluble in 100% alcohol, chloro-

form, and ether.

hexacalcium phytate. See calcium phytate.

Derivation: Chlorination of benzene in actinic light.

Method of purification: Fractional crystallization.

hexachloroacetone. (hexachloro-2-propa- The technical grade may run 10–15% ␥ isomer but

none). can be brought up to 99% (lindane).

CAS: 116-16-5. Cl

CCOCCl

. Grade: Technical (mixture of isomers), 25% ␥ iso-

Properties: Yellow liquid. Bp 204C, fp −3C, d 1.744 mer, and 99% ␥ isomer (lindane).

(12/12C). Slightly soluble in water; soluble in ace- Hazard: Toxic by ingestion and inhalation, absorbed

tone. by skin, strong irritant to skin and eyes. CNS depres-

644HEXACHLOROCYCLOPENTADIENE

sant. Use may be restricted. TLV: (lindane) 0.5 mg/ irritant, absorbed by skin. TLV: 1 ppm; suspected

. human carcinogen.

Use: Component of insecticides; toxic to flies, cock- Use: Organic synthesis, retarding agent in fermenta-

roaches, aphids, grasshoppers, wire worms, and boll

tion, camphor substitute in nitrocellulose, pyrotech-

weevils.

nics and smoke devices, solvent, explosives.

hexachlorocyclopentadiene. (perchlorocy-

hexachloromethylcarbonate. (triphosgene).

clopentadiene).

(OCCl

)

CO.

CAS: 77-47-4. C

Properties: White crystals; odor similar to that of

Properties: Pale-yellow liquid; pungent odor. Bp

phosgene. D approximately 2, bp 205–206C (partial

239C, fp 9.6C, d 1.717 (15/15C), bulk d 14.30 lb/gal

decomposition), mp 78–79C. Decomposed by hot

(15.5C), refr index 1.563 (25C), flash p none. Non-

water and alkali hydroxides. Only slowly aceted

flammable.

upon by cold water. Soluble in alcohol, benzene,

Grade: Technical.

ether.

Hazard: Toxic by ingestion, inhalation, and skin

Derivation: Chlorination of dimethyl carbonate ex-

absorption. TLV: TWA 0.01 ppm; not classifiable as

posed to direct sunlight.

a human carcinogen.

Hazard: Strong irritant to eyes and skin.

Use: Intermediate for resins, dyes, pesticides, fungi-

Use: Lachrymator.

cides, pharmaceuticals.

hexachloromethyl ether. O(CCl

)

2,3,4,4,5,5-hexachloro-2-cyclopenten-1-one.

Properties: Liquid; phosgenelike odor. D 1.538

CAS: 2514-52-5. mf: C

(18C), bp 98C (partial decomposition).

Hazard: A poison by ingestion. Moderately toxic by

Derivation: Chlorination of dichloromethyl ether.

inhalation.

Hazard: Strong irritant to eyes and skin.

2,2

′

,4,4

′

,5,5

′

-hexachlorodiphenyl ether.

hexachloronaphthalene.

CAS: 71859-30-8. mf: C

CAS: 1335-87-1. C

Hazard: A reproductive hazard.

Properties: White solid.

Hazard: Toxic by inhalation, strong irritant, ab-

2,2

′

,4,4

′

,5,6

′

-hexachlorodiphenyl ether. sorbed by skin. TLV: 0.2 mg/m

CAS: 106220-81-9. mf: C

Hazard: A reproductive hazard.

1,2,3,4,6,7-hexachloronaphthalene.

CAS: 103426-96-6. mf: C

hexachlorodiphenyl oxide. (chlorinated di- Hazard: A reproductive hazard.

phenyl oxide).

CAS: 31242-93-0. C

1,2,3,5,6,7-hexachloronaphthalene.

Properties: Light-yellow, very viscous liquid. Bp

CAS: 103426-97-7. mf: C

230–260C (8 mm Hg), d 1.60 (20/20C), bulk d 13.12

Hazard: A poison by ingestion.

lb/gal (25C), refr index 1.621 (25C), flash p none.

Soluble in methanol, ether; very slightly soluble in

hexachlorophene. (2,2

′

-methylene-bis-(3,4,6-

water. Nonflammable.

trichlorophenol); bis-(3,5,6-trichloro-2-hydroxy-

Hazard: Toxic by ingestion. TLV: 0.5 mg/m

phenyl)methane).

Use: Solvent, intermediate.

CAS: 70-30-4. (C

HCl

OH)

Properties: White, free-flowing powder; odorless.

1,1,1,4,4,4-hexachloro-1,4-disilabutane.

Mp 161–167C. Soluble in acetone, alcohol, ether,

See bis(trichlorosilyl)ethane.

chloroform; insoluble in water.

Derivation: Condensation of 3,4,5-trichlorophenol

hexachloroendomethylene with formaldehyde in the presence of sulfuric acid.

tetrahydrophthalic acid. See chlorendic Hazard: FDA prohibits use unless prescribed by a

acid. physician.

Use: Topical antiinfective (restricted), germicidal

soaps, veterinary medicine.

hexachloroendomethylene

tetrahydrophthalic anhydride. See chlo-

rendic anhydride.

hexachloro-2-propane. See hexachloroace-

tone.

hexachloroethane. (perchloroethane; carbon

trichloride; carbon hexachloride).

hexachloropropylene. (hexachloropropene;

CAS: 67-72-1. Cl

CCCl

. perchloropropylene). CCl

CCl:CCl

Properties: Colorless crystals: camphorlike odor. D Properties: Water-white liquid. Bp 210C. Insoluble

2.091, mp 185C, bp sublimes at 185C. Soluble in in water; miscible with alcohol, ether, chlorinated

alcohol and ether; insoluble in water. compounds.

Hazard: Toxic by ingestion and inhalation, strong Use: Solvent, plasticizer, hydraulic fluid.

645 HEXAETHYLDISTANNOXANE

hexacontane. C

122

. High molecular weight hexadecyl mercaptan. See cetyl mercaptan.

hydrocarbon.

Properties: Waxy solid. Mp 101C.

tert-hexadecyl mercaptan. C

SH.

Hazard: Combustible.

Properties: Colorless liquid; unpleasant odor. Boil-

ing range 121–149C (5 mm Hg), d 0.874 (60/60F),

hexacosanoic acid. See cerotic acid.

refr index 1.474 (20C), flash p 265F (129.4C).

Hazard: Combustible.

n-hexadecane. (cetane). C

Use: Polymer modification.

Properties: Colorless liquid. D 0.77335 (20/4C),

See thiol.

flash p 200F (93C), bp 286.5C, mp 18.14C, refr

index 1.43435 (20C). Soluble in alcohol, acetone,

hexadecyltrichlorosilane.

ether; insoluble in water, autoign temp 401F (205C).

CAS: 5894-60-0. C

SiCl

Grade: Technical, ASTM.

Properties: Colorless to yellow liquid. Bp 269C, d

Hazard: Combustible.

0.996 (25/25C), refr index 1.4568 (25C), flash p

Use: Solvent, organic intermediate, ignition standard

295F (146C).

for diesel fuels.

Derivation: By Grignard reaction of silicon tetra-

See cetane number.

chloride and hexadecylmagnesium chloride.

Grade: Technical.

hexadecanoic acid. See palmitic acid.

Hazard: Strong irritant. Combustible. Evolves hy-

drogen chloride in the presence of moisture.

1-hexadecanol. See cetyl alcohol.

Use: Intermediate for silicones.

hexadecanoyl chloride. See palmitoyl chlo-

hexadecyltrimethylammonium bromide.

ride.

See cetyl trimethylammonium bromide.

(z)-7-hexadecenal.

hexadecyltrimethylammonium chloride.

CAS: 56797-40-1. mf: C

CAS: 112-02-7. mf: C

N•Cl.

Hazard: Low toxicity by ingestion.

Hazard: A poison by ingestion and skin contact.

Source: Natural product.

1,4-hexadiene.

(z)-9-hexadecenal.

CAS: 42296-74-2. H

C:CHCH

HC:CHCH

CAS: 56219-04-6. mf: C

Properties: Colorless liquid. D 0.6996 (20/4C), bp

Hazard: Low toxicity by ingestion.

64C (745 mm Hg), refr index 1.4162 (20C), flash p

Source: Natural product.

−6F (−21.1C). Insoluble in water.

Derivation: Reaction between ethylene and butadi-

1-hexadecene. (cetene; ␣-hexadecylene).

ene with a special catalyst.

(CH

)

CH:CH

Hazard: Highly flammable, explosive limits in air

Properties: Colorless liquid. Mp 4C, bp 274C, flash

2–6.1%.

p 200F (93C), d 0.784 (15/4C), refr index 1.441

Use: As third monomer in EPDM synthetic elas-

(20C). Insoluble in water; soluble in alcohol, ether,

tomers.

petroleum, and coal tar solvents.

Derivation: Treatment of cetyl alcohol with phos-

2,4-hexadienedial, (e,e)-.

phorus pentoxide.

CAS: 18409-46-6. mf: C

Grade: 95% purity.

Hazard: A poison.

Hazard: Combustible.

Use: Organic synthesis.

2,4-hexadienoic acid. See sorbic acid.

cis-9-hexadecenoic acid. See palmitoleic

1,5-hexadiyne. See dipropargyl.

acid.

hexa-2-ethylbutoxydisiloxane.

(z)-11-hexadecenol.

[(CH

CH(C

)CH

Si]

CAS: 56683-54-6. mf: C

Properties: Colorless oil. Bp 195C (0.2 mm Hg).

Hazard: Low toxicity by ingestion.

Derivation: Reaction of silicon tetrachloride, 2-

Source: Natural product.

ethylbutanol, and water.

Hazard: Combustible.

(z)-7-hexadecen-1-ol acetate.

Use: Aircraft hydraulic fluid.

CAS: 23192-42-9. mf: C

Hazard: Moderately toxic by ingestion and skin con-

tact. Low toxicity by inhalation.

hexaethyldistannoxane.

Use: Agricultural chemical.

CAS: 1112-63-6. mf: C

OSn

Properties: Air-sensitive liquid. D: 1.377 @ 20°, bp:

6-hexadecenolide. See ambrettolide. 272°.

646HEXAETHYLDISTANNTHIANE

Hazard: A poison. TWA 0.1 mg(Sn)/m

; STEL 0.2 Use: Dielectric and coolant, aerosol propellant, re-

mg/m

(skin) frigerant.

Use: Drug.

2-(1,1,2,3,3,3-hexafluoro-2-(heptafluoro-

propoxy)propoxy)-2,3,3,3-tetrafluoro-

hexaethyldistannthiane.

propanoic acid.

CAS: 994-50-3. mf: C

SSn

CAS: 13252-14-7. mf: C

Properties: A liquid. D: 1.431 @ 20°, bp: 187−188°

Hazard: Moderately toxic by inhalation and skin

@ 20 mm.

contact. A moderate eye irritant.

Hazard: A poison. TWA 0.1 mg(Sn)/m

; STEL 0.2

mg/m

(skin)

hexafluorophosphoric acid.

Use: Drug.

CAS: 16940-81-1. HPF

Properties: (65% solution) Colorless, fuming liquid.

hexaethyl tetraphosphate. (HETP).

D 1.81, mp 31C (6H

O). Stable in neutral and alka-

CAS: 757-58-4. A mixture of ethyl phosphates and

line solutions.

ethyl pyrophosphates (TEPP).

Hazard: Strong irritant to tissue.

Properties: Yellow liquid. D 1.26–1.28 (25/4C), fp

Use: Metal cleaners, electrolytic or chemical polish-

−90C, refr index 1.427, decomposes at high temper-

ing agents for the formation of protective coatings

atures. Soluble or miscible with water and many

for metal surfaces, and as a catalyst.

organic solvents except kerosene; hydrolyzes in low

concentration; hygroscopic.

1,1,1,2,3,3-hexafluoropropane.

Hazard: Toxic by ingestion, inhalation, and skin

CAS: 431-63-0. mf: C

absorption; cholinesterase inhibitor.

Hazard: Low toxicity by inhalation. A reproductive

Use: Contact insecticide.

hazard.

Note: Hexaethyl tetraphosphate and compressed gas

mixture not accepted by air or by passenger rail. For

1,1,1,3,3,3-hexafluoropropane.

details consult regulations.

CAS: 690-39-1. mf: C

Hazard: Moderately toxic by inhalation route.

hexafluoroacetone.

CAS: 684-16-2. CF

COCF

hexafluoropropylene. (perfluoropropene).

Properties: Colorless, hygroscopic, highly reactive

CF:CF

gas. Bp −27C, fp −122C, liquid density 1.33 (25C),

Properties: Gas. Fp −156C, bp −29C, d 1.583 (−40/

minimum purity 95%.

4C).

Hazard: Toxic by inhalation and skin absorption.

Reacts vigorously with water and other substances,

hexafluoropropylene epoxide. (HFPO).

releasing considerable heat. Nonflammable. TLV:

0.1 ppm.

Derivation: Oxidation of hexafluoropropylene with

Use: Intermediate in organic synthesis.

alkaline hydrogen peroxide at approximately −30C.

Use: Monomer for HFPO polymers that are heat

hexafluoroacetone bisphenol a.

resistant to 410C. Noncombustible.

CAS: 1478-61-1. mf: C

See “Freon E”; “Krytox.”

Hazard: Moderately toxic by ingestion.

hexafluorosilicic acid. See fluosilicic acid.

hexafluorobenzene. C

Properties: Liquid. Bp 80.26C, mp 5.2C, d 1.613.

hexaglycerol. See trimethylolpropane, poly-

Hazard: Toxic by inhalation. Combustible.

glycerol.

Use: Chemical intermediate, solvent in NMR spec-

troscopy.

hexahydric alcohol. See mannitol, sorbitol,

and dulcitol.

hexafluorocalcitriol.

CAS: 83805-11-2. mf: C

hexahydroaniline. See cyclohexylamine.

Hazard: A poison by ingestion.

hexahydrobenzene. See cyclohexane.

hexafluorodiphenylolpropane. See hexafl-

uoroacetone bisphenol a.

hexahydrobenzoic acid. (cyclohexanecar-

boxylic acid [a naphthenic acid]). C

COOH.

hexafluoroethane. (fluorocarbon 116). Properties: Colorless monoclinic prisms. Mp 31C,

CAS: 76-16-4. CF

. bp 233C, d 1.048 (15/4C), refr index 1.4561

Properties: A gas. Bp −78.2C, d 1.59. Insoluble in (33.8C). Slightly soluble in water; soluble in alcohol

water; slightly soluble in alcohol. One of the most and ether.

stable of all organic compounds. Use: Paint and varnish driers, dry-cleaning soaps,

Grade: 99.6% pure. lubricating oils, stabilizer for rubber.

647 HEXAMETHYLENEDIAMINE

hexahydrocresol. See methylcyclohexanol. hexametapol. See hempa.

hexamethonium chloride. (hexamethylene-

hexahydro-4,7-methanoindandimethanol.

bis(trimethylammonium) chloride).

See tricyclodecanedimethanol.

CAS: 60-25-3. (CH

)

NCl(CH

)

NCl(CH

)

Properties: White, crystalline, hygroscopic powder;

hexahydromethylphenol. See methylcyclo-

faint odor. Mp 289–292C (decomposes). Very solu-

hexanol.

ble in water; soluble in alcohol, methanol, and n-

propanol; insoluble in chloroform and ether. Avail-

hexahydrophenol. See cyclohexanol.

able commercially as unhydrated form or as

dihydrate.

hexahydrophthalic anhydride. (1,2-cyclo-

Use: Medicine (antihypertensive).

hexandicarboxylic anhydride). C

(CO)

Properties: Clear, colorless, viscous liquid that be-

hexamethylbenzene. C

or C

(CH

)

comes a glassy solid at 35–36C. Bp 158C (17 mm

Properties: Colorless plates. Bp 265C, mp 165.5C.

Hg), d 1.19 (40C). Miscible with benzene, toluene,

Soluble in alcohol; insoluble in water.

acetone, carbon tetrachloride, chloroform, ethanol,

Hazard: Combustible.

and ethyl acetate; slightly soluble in petroleum

ether.

hexamethylcyclotrisilazane.

Hazard: Toxic by inhalation, strong irritant to eyes

CAS: 1009-93-4. mf: C

and skin.

Hazard: Moderately toxic by ingestion.

Use: Intermediate for alkyds, plasticizers, insect re-

pellents, and rust inhibitors; hardener in epoxy

hexamethyldiaminoisopropanol diiodide.

resins.

See propiodal.

hexahydropyridine. See piperidine.

hexamethyldisilazane. (HMDS).

CAS: 999-97-3. (CH

)

SiNHSi(CH

)

hexahydrotoluene. See methylcyclohexane.

Properties: Liquid. D 0.77 (25C), refr index 1.4057

(25C), bp 125C, flash p 77F (25C). Soluble in ace-

hexahydro-1,3,5-trinitro-sym-triazine. See

tone, benzene, ethyl ether, heptane, perchloroethy-

cyclonite.

lene; reactive with methanol and water.

Grade: 99% min.

hexahydroxycyclohexane. See inositol.

Hazard: Flammable, moderate fire risk.

Use: Chemical intermediate, chromatographic

hexahydroxylene. See dimethylcyclohexane.

packings.

hexaisobutylditin.

hexamethyldistannane. See hexamethylditin.

CAS: 3750-18-3. mf: C

Hazard: A poison. TWA 0.1 mg(Sn)/m

; STEL 0.2

hexamethylditin.

mg/m

(skin)

CAS: 661-69-8. mf: C

Properties: Crystals from pet ether. Mp: 28°, bp:

hexakis(methoxymethyl)melamine.

182°.

Hazard: A poison by ingestion. TWA 0.1 mg(Sn)/

❘

C(NR)NC(NR)N

❘

C(NR) where R

(CH

OCH

)

; STEL 0.2 mg(Sn)/m

(skin).

Use: Crosslinking agent for alkyds, epoxies, cellulo-

Use: Agricultural chemical.

sics, and vinyls.

hexamethylene. See cyclohexane.

n-hexaldehyde. (caproic aldehyde).

CAS: 66-25-1. CH

(CH

)

CHO.

hexamethylenediamine. (1,6-diaminohexane;

Properties: Colorless liquid; sharp aldehyde odor. D

1,6-hexanediamine).

0.8156 (20/20C), bp 128.6C, vap press 10.5 mm Hg

CAS: 124-09-4. H

N(CH

)

(20C), flash p 90F (32.2C) (OC), bulk d 6.9 wt/gal

Properties: Colorless leaflets. Mp 39–42C, bp 205C.

(20C), fp −56.3C. Immiscible with water.

Soluble in water; slightly soluble in alcohol and

Grade: Technical.

benzene.

Hazard: Flammable, moderate fire risk.

Derivation: (1) Reaction of adipic acid and ammonia

Use: Organic synthesis of plasticizers, rubber chemi-

(catalytic vapor phase) to yield adiponitrile, fol-

cals, dyes, synthetic resins, insecticides.

lowed by liquid-phase catalytic hydrogenation. (2)

Chlorination of butadiene followed by reaction with

“Hexalin” [Du Pont]. TM for cyclohexanol sodium cyanide (cuprous chloride catalyst) to 1,4-

(usually shipped with 2.25% methanol as anti- dicyanobutylene and hydrogenation.

freeze). Hazard: Toxic by ingestion, strong irritant to tissue.

Hazard: Toxic by ingestion. TLV: 0.5 ppm. Combustible.

648HEXAMETHYLENEDIAMINE

Use: Formation of high polymers, e.g., nylon 66.

hexamethylphosphoramide. See hempa.

hexamethylphosphoric triamide. See

hexamethylenediamine carbamate. See

hempa.

“Diak.”

hexamethyltetracosahexaene. See squalene.

hexamethylene diisocyanate.

CAS: 822-06-0. OCN(CH

)

NCO.

hexamethyltetracosane. See squalane.

Properties: Liquid. D 1.04 (25/15.5C), flash p 284F

(140C).

hexamine. See hexamethylenetetramine.

Hazard: TLV: 0.005 ppm. Combustible.

Use: Chemical intermediate.

hexanaphthene. See cyclohexane.

hexamethylene glycol. (1,6-hexanediol).

n-hexane.

CAS: 629-11-8. CH

OH(CH

)

OH.

CAS: 110-54-3. CH

(CH

)

Properties: Crystalline needles. Mp 42C, bp 210C,

Properties: Colorless, volatile liquid; faint odor. D

refr index 1.457, d 0.953 (50C), flash p 130C (266F).

0.65937 (20/4), bp 68.742C, fp −95C, refr index

Derivation: Reduction of adipic acid ester with cop-

1.37486 (20C), flash p −9F (−22.7C), autoign temp

per chromite catalyst.

500F (260C). Soluble in alcohol, acetone, and ether;

Hazard: Toxic by ingestion.

insoluble in water.

Use: Solvent, intermediate for high polymers (nylon,

Derivation: By fractional distillation from petrole-

polyesters), coupling agent, coil coating.

um (molecular sieve process).

Grade: 85%, 95%, 99%, spectro, research, and nano-

hexamethyleneimine.

grade.

CAS: 111-49-9. C

NH (cyclic).

Hazard: Flammable, dangerous fire risk. TLV: 50

Properties: Clear, colorless liquid; ammonia-like

ppm.

odor. Bp 138C, fp −37C, d 0.8799 (20/4C).

Use: Solvent, especially for vegetable oils; low- tem-

Hazard: Toxic by ingestion, strong irritant to tissue.

perature thermometers; calibrations; polymeriza-

Use: Intermediate for pharmaceutical, agricultural,

tion reaction medium; paint diluent; alcohol denatu-

and rubber chemicals.

rant.

hexamethylenetetramine. (methenamine;

2-hexanecarboxylic acid.

HMTA; aminoform; hexamine, erroneously

CAS: 4536-23-6. mf: C

“Hexamethyleneamine”).

Hazard: A reproductive hazard.

CAS: 100-97-0. (CH

)

. A heterocyclic fused ring

structure.

hexanedioic acid. See adipic acid.

1,6-hexanediol. See hexamethylene glycol.

hexanedione-2,5. See acetonyl acetone.

1,2,6-hexanetriol.

Properties: White, crystalline powder or colorless

CAS: 106-69-4.

lustrous crystals; practically odorless. D 1.27 (25C);

HOCH

CH(OH)CH

OH.

soluble in water, alcohol, and chloroform; insoluble

Properties: Water-white liquid. D 1.1063, sets to

in ether; sublimes approximately 200C; partly de-

glass at approximately −20C (fp under controlled

composes.

conditions 32.8C), bp (178C) 5 mm Hg, flash p 380F

Derivation: Action of ammonia on formaldehyde.

(193C). Miscible with water.

Grade: Technical, NF (as methenamine).

Hazard: Combustible.

Hazard: Skin irritant. Flammable, dangerous fire

Use: Alkyd and polyester resin intermediate, soften-

risk.

er, moistening agent, and solvent.

Use: Curing of phenolformaldehyde and resorcinol-

formaldehyde resins, rubber-to-textile adhesives,

hexanitrodiphenylamine. (hexil; hexyl; hex-

protein modifier, organic synthesis, pharmaceuti-

ite; dipicrylamine). (NO

)

NHC

(NO

)

cals, ingredient of highly explosive cyclonite, fuel

Properties: Yellow solid. Mp 238–244C, decom-

tablets, rubber accelerator, fungicide, corrosion in-

poses violently at higher temperatures. Insoluble in

hibitor, shrink-proofing textiles, antibacterial.

water and alcohol; soluble in alkalies and warm

acetic or nitric acid.

hexamethylmelamine. See hemel.

Derivation: Nitration of diphenylamine, also from

dinitrochlorobenzene.

hexamethylpararosaniline chloride. See Hazard: Explodes on shock or exposure to heat,

methyl violet. dangerous.

649 HEXESTROL

Use: Booster explosive, analysis for potassium.

“Hexaphos” [FMC]. TM for a glassy phos-

phate of high molecular weight having superior wa-

hexanitrodiphenyl sulfide. (dipicryl sul- ter-softening properties.

fide). [(NO

)

]

S. Use: Water-softening, boiler-scale control, compo-

nent of cleansers, laundry mixes, dishwashing com-

Properties: Golden-yellow leaflets. Mp 234C. Spar-

pounds, pitch control in pulp industry, prevention of

ingly soluble in alcohol and ether; more soluble in

lime soap deposits in textile operations.

glacial acetic acid and acetone.

Derivation: Interaction of picryl chloride and sodi-

um thiosulfate in alcohol solution in the presence of

hexapropyldistannthiane.

magnesium carbonate.

CAS: 7328-05-4. mf: C

SSn

Hazard: Explodes on shock or exposure to heat;

Hazard: A poison. TWA 0.1 mg(Sn)/m

; STEL 0.2

dangerous.

mg/m

(skin)

Use: High explosive.