EADC. Abbreviation for ethylaluminum dichlo- “Easy Glide” [Swix]. TM for ski wax.

ride. Use: For no-wax skis for better performance and to

avoid icing.

EAK. Abbreviation for ethyl amyl ketone.

“Ebecryl 605a” [Cytec].

CAS: 84593-14-6.

earth. (1) Any siliceous or claylike compound or

Hazard: A mild skin irritant.

mixture, e.g., fuller’s earth, diatomaceous earth. (2)

Use: Industrial coating for wood, plastics, paper, and

A natural metallic oxide, sometimes used as a pig-

electronics including parquet and safety glass inter-

ment, e.g., red and yellow iron oxide, ocher, or

layers.

umber. (3) An oxide of any of a series of chemically

related metals that are difficult to separate from their

ebonite. See rubber, hard.

oxides or other combined forms, specifically, rare

earths, alkaline earths.

ebullator. A solid substance or surface used to

See specific entry.

prevent superheating of liquids above their boiling

point.

earth wax. General name for ozocerite, ceresin,

and montan waxes.

ebullioscope. (ebulliscope). An instrument to

See wax.

determine concentration by means of boiling points

of liquids.

EASC. Abbreviation for ethylaluminum sesqui-

chloride.

ebulliscope. See ebullioscope.

“Easibrom” [Nalco]. TM for microbiological

ecabet sodium.

control.

CAS: 86408-72-2. mf: C

S•Na.

Use: For cooling and water systems.

Hazard: Moderately toxic by ingestion.

“Easperol” [Henkel]. TM for sulfated fatty

“Ecdel” [Eastman]. TM for an elastomer

alcohol–vegetable-oil mixtures.

which imparts excellent low-temperature resistance

Use: Replacement additives for sulfated sperm-oil

that significantly reduces product loss due to flex

types in production of leather.

cracking and shattering during cold weather distri-

bution.

“Eastar” [Eastman]. TM for PETG copolyes-

Use: Applications where low extraction of plasticiz-

ter useful in a variety of processes and applications

ers from the product, flex crack resistance, and utili-

because of its toughness, clarity, and good melt

ty in harsh environments are required.

strength.

Use: For blister packaging and thermoformed con-

echinomycin.

tainers for refrigerated/frozen foods, candies, and

CAS: 512-64-1. C

sundries.

Properties: Colorless crystals. Slightly hygroscopic,

mp 218C. Soluble in fats, chloroform, dioxane; in-

East India. A type of fossil or semirecent resin

soluble in water.

similar to dammar. Varieties are batu, black, and

Use: Medicine (antibiotic).

pale.

Use: In spirit and oleoresinous varnishes.

ECM. See extracellular matrix.

“Eastobond” [Eastman]. TM for a series of

ecology. The study of the interactions between

hot-melt adhesives used in the packaging industry

plant and animal organisms and their environment;

for bonding paper, board, film, foil, and glassine.

the latter is conceived to include everything that is

not an intrinsic part of the organism and thus in-

“Eastone” [Eastman]. TM for disperse dye-

cludes both living and nonliving components.

stuffs for use with acetate and nylon fibers.

Though primarily a branch of biology, ecology does

involve chemistry in respect to plant and animal

“Eastotac” [Eastman]. TM for hydrogenated nutrients, metabolism, photosynthesis, etc., espe-

aliphatic hydrocarbon tackifying resins. cially interferences that may occur in connection

Derivation: Produced from petroleum feedstock by with these. Thus, insecticides, chemical-waste dis-

polymerization followed by hydrogenation. posal, air and water pollution, oil spills, and radioac-

489

490ECONOMIC POISON

tive contaminants have direct bearing on the ecology tion, nor are medicinal oils derived from animal

of a given area. sources (cod liver, mineral oil, etc.).

See environmental chemistry.

Edman degradation. Sequential degradation

economic poison. See pesticide. of peptides beginning at the N-terminal residue

based on the reaction of phenylisocyanate with the

economics, chemical. See chemical eco- ␣-amino group of the terminal amino acid of the

nomics. peptide chain.

economizer. A device that acts like a heat ex- EDTA. Abbreviation for ethylenediaminetetraa-

cetic acid.

changer whereby the heat produced by an operation

is used to warm incoming air or water. It is widely

used in the paper industry, in boilers, and in chemi-

EDTAN. Abbreviation for ethylene diamine tet-

cal processing. Heat recovery up to 30% is possible. raacetonitrile.

ecosystem. The organisms of an ecologic com- EDTA Na

Abbreviation for ethylene diamine

munity together with the physical environment that tetraacetic acid tetrasodium salt.

they occupy. See tetrasodium EDTA.

“Ecozyme” [Swan]. TM for a xylanase-based effect. An evaporation-condensation unit.

enzyme that reduces chemical bleaching agents up See evaporation.

to 25% with enhanced pulp quality.

Use: Reduces chlorinated effluent discharge levels in

effective charge. The value of charge that, mul-

pulp mills.

tiplied by the actual distance between two atoms of a

heteropolar, diatomic molecule, gives the actual di-

ECTEOLA-cellulose. (epichlorohydrin trieth- pole moment.

anolamine cellulose). A dry, powdered cellulose

derivative containing tertiary amine groups.

effervescence. The rapid escape of gas from a

Use: As an anion exchanger in chromatography. It is

liquid or a mixture.

less basic than DEAE-cellulose and serves to sepa-

rate viruses, nucleic acids, and nucleoproteins.

efflorescence. Loss of combined water mole-

cules by a hydrate when exposed to air, resulting in

EDAP. See EDC (reagent).

partial decomposition indicated by presence of a

powdery coating on the material. This commonly

EDB. Abbreviation for ethylene dibromide. occurs with washing soda (Na

•10H

O), which

loses almost all its water constituent spontaneously.

EDC (reagent).

CAS: 25952-53-8. mf: C

•ClH. effluent. Any gas or liquid emerging from a pipe

Use: An antibiotic. or similar outlet; usually refers to waste products

Hazard: A poison. from chemical or industrial plants, as stack gases or

liquid mix.

Edeleanu process. A solvent extraction pro-

cess using liquid sulfur dioxide for the removal of

egg. (1) A large gamete without flagellae that is

undesirable aromatics from heavy lubrication oils. fertilized by a sperm cell. An egg cell is also called

an ovum. (2) A complex multicellular structure in

which an animal embryo develops.

edestin. A protein having a molecular weight of

310,000, obtained from hempseed. Closely similar

proteins occur in seeds of pumpkin, squash, etc.

egg oil. Fatty oil obtained from egg yolk by

extraction with ethylene dichloride; insoluble in wa-

ter, but readily forms emulsions on strong agitation.

edetate. See ethylenediaminetetraacetic acid

Use: Ointments, cosmetic creams.

(note).

egg yolk.

edible oil. As commonly used, the term refers to

Properties: Yellow, semisolid mass. D 0.95, mp

any fatty oil obtained from the flesh or seeds of

22C. High cholesterol content.

plants that is used primarily in foodstuffs (marga-

Grade: Technical, edible.

rine, salad dressing, shortening, etc.). Among these

Use: Baking, dairy products, mayonnaise, pharma-

are olive, safflower, cottonseed, coconut, peanut,

ceuticals, soap, perfumery.

soybean, and corn oils, some of which may be hy-

See albumin, egg.

drogenated to solid form. They vary in degree of

unsaturation, ranging from 78% for safflower to

about 10% for coconut. Castor oil, though technical-

EHEC. Abbreviation for ethyl hydroxyethyl cel-

ly edible, is not usually considered in this classifica- lulose.

491 ELAIDIC ACID

Ehrlich, Paul. (1854–1915). A native of Sile- Einhorn-Brunner reaction. Formation of

sia, Ehrlich is considered the founder of the science substituted 1,2,4-triazoles by condensation of hy-

of chemotherapy, or the treatment of diseases by drazines or semicarbazides with diacylamines in the

chemical agents. He did fundamental work on im- presence of acid catalysts.

munity, which earned him the Nobel Prize in medi-

cine in 1908, and also developed the famous

einstein. The energy acquired by a gram-molecu-

neoarsphenamine (salvarsan or 606) treatment for

lar weight of a substance when each molecule ab-

syphilis (1910), which was not improved upon until

sorbs a quantum of excitation energy.

the discovery of penicillin.

einsteinium. Es. A synthetic radioactive element

with atomic number 99 and aw 253, discovered in

Ehrlich-Sachs reaction. Formation of anils by

the debris from the 1952 hydrogen-bomb explosion.

the base-catalyzed condensation of compounds con-

Einsteinium has since been prepared in a cyclotron

taining active methylene groups with aromatic ni-

by bombarding uranium with accelerated nitrogen

troso compounds.

ions, in a nuclear reactor by irradiating plutonium or

californium with neutrons, and by other nuclear re-

eicosamethyl nonasiloxane. C

actions. The element is named for Albert Einstein. It

Properties: Inert liquid. Bp 173C (5 mm Hg), d

has chemical properties similar to those of the rare-

0.918. Soluble in benzene and light hydrocarbons;

earth metal holmium. Isotopes are known with mass

slightly soluble in alcohol.

numbers ranging from 246 to 253. Einsteinium has

Use: Silicone fluids, foam suppressor in lubricating

valence of 2, and the lowest heat of vaporization of

oils.

any divalent element.

See actinide series.

eicosane. C

. Most technical eicosane is a

mixture of predominantly straight-chain hydrocar-

eka-. Prefix referring to element in next-lower

bons averaging 20 carbon atoms to the molecule.

position in the same group in the periodic system.

Properties: (pure n-eicosane): White, crystalline sol-

id. Fp 36.7C, bp 205C (15 mm Hg), flash p 212F

ekahafnium. One of the last-discovered transu-

(100C), refr index 1.4348 (20C), d 0.778 (at melting

ranic elements; atomic number 104. It has two ␣-

point). Insoluble in water; soluble in ether. Can be

emitting isotopes (257 and 259) and possibly a third

readily chlorinated. Combustible.

(258). The former, made by bombardment of cali-

Grade: Pure normal (99+%), technical.

fornium-249 with carbon-12 nuclei, has a half-life

Use: Cosmetic, lubricants, plasticizers.

of five seconds and decays into nobelium-253. The

259 isotope, made by merging a carbon-13 nucleus

eicosanoic acid. See arachidic acid.

with californium-249, has a half-life of three sec and

decays to nobelium-255.

eicosanoid. Any of a number of biochemically

active compounds resulting from enzymic oxidation

“Ekonol” [Carborundum]. TM for an engi-

of arachidonic acid, e.g., prostaglandins, thrombox-

neering plastic composed of poly-p-oxybenzoate.

anes, prostacyclin, and leukotrienes. As a group,

Resistant to temperatures above 600C, self-lubricat-

they compose what is known as the arachidonic acid

ing surface.

cascade. They have many pharmacological and

Use: In pumps handling corrosive liquids, protective

medical possibilities.

coating for titanium skins on supersonic transports,

See prostaglandin; arachidonic acid.

disk brakes, etc.

1-eicosanol. See arachidyl alcohol.

“ELA” [Du Pont]. Brand name for elastomer

lubricating agent, a mixture of phosphate esters.

5,8,11,14-eicostetraenoic acid. See arachi-

Light-amber liquid.

donic acid.

Use: Unvulcanized rubbers.

eigenenergy. Quantity of energy corresponding

elaboration. A term used in biochemistry to de-

to a time-invarient atomic state.

scribe chemical transformations within an organism

resulting in formation of specific types of sub-

eigenfunction. Wave function corresponding to

stances; for example, plants elaborate proteins and

a state with a definite value of some quantity.

fats, and poisonous snakes elaborate their venom. It

also refers to formation of metabolic end products

such as purines and uric acid.

Eigen, Manfred. (1927– ). A German physicist

who won the Nobel Prize for chemistry in 1967. His

research concerned the rate of hydrogen-ion forma-

elaidic acid. (trans-9-octadecenoic acid).

tion through disassociation of water. He also was CH

[CH

]

HC:CH[CH

]

COOH. The trans form of

concerned with enzyme control. He received his an unsaturated fatty acid of which the cis form is

degree at the University of Gottingen. oleic acid.

492ELAIDINIZATION

high polymers having properties similar to those of

vulcanized natural rubber, namely, the ability to be

stretched to at least twice their original length and to

retract very rapidly to approximately their original

Properties: White solid. D 0.8505 (79/4C), mp

length when released. Among the better-known

43.7C, bp 288C (100 mm Hg), 234C (15 mm Hg),

elastomers introduced since the 1930s are styrene-

refr index 1.4358 (79C). Insoluble in water; soluble

butadiene copolymer, polychloroprene (neoprene),

in alcohol, ether, benzene, and chloroform. Com-

nitrile rubber, butyl rubber, polysulfide rubber

bustible.

(“Thiokol”), cis-1,4-polyisoprene, ethylene-propyl-

Derivation: Synthesized from oleic acid by elaidini-

ene terpolymers (EPDM rubber), silicone rubber,

zation.

and polyurethane rubber. These can be cross-linked

Grade: Purified, 99+%.

with sulfur, peroxides, or similar agents. The term

Use: Medical research, reference standard in chroma-

was later extended to include un-cross-linked polyo-

tography.

lefins that are thermoplastic; these are generally

known as TPO rubbers. Their extension and retrac-

elaidinization. Originally the reaction by which

tion properties are notably different from those of

oleic acid is converted into elaidic acid, but now

thermosetting elastomers, but they are well adapted

used in a more general sense to indicate the conver-

to such specific uses as wire and cable coating,

sion of any unsaturated fatty acid or related com-

automobile bumpers, vibration dampers, and spe-

pound from the geometric cis to the corresponding

cialized mechanical products.

trans form. Nitrous acid and selenium compounds

are commonly used as catalysts for this reaction.

Elbs persulfate oxidation. Hydroxylation of

The resulting trans acids are more stable to oxida-

phenols to p-diphenols by potassium persulfate in

tion.

alkaline solution.

elargin.

Elbs reaction. Formation of anthracenes by in-

CAS: 2169-75-7. mf: C

NO•C

tramolecular condensation of diaryl ketones con-

Hazard: A poison by ingestion.

taining a methyl or methylene substituent adjacent

to the carbonyl group.

elasticity. The ability of a material to recover its

original shape partially or completely after the de-

forming force has been removed. The small amount

elcatonin. See carbocalcitonin.

of deformation that is not recovered is called perma-

nent set or permanent elongation. Among common

electric double layer. A diffuse aggregation

materials, glass and some metals are virtually 100%

of positive and negative electric charges surround-

elastic, whereas vulcanized rubber and other elasto-

ing a suspended colloidal particle which aids in

meric substances are in the range of 90% elastic after

maintaining its stability. According to the Gouy-

extension to rupture. So-called perfect elasticity is a

Freundlich theory, advanced about 1920, a close-

property of atoms that show no energy loss on colli-

packed array of charges is attached to the surface of

sion.

the particle while a diffuse layer of charges of oppo-

See modulus of elasticity; stress; strain; plasticity.

site sign extends into the liquid. The particle is elec-

trically neutral. There is an electrokinetic potential

elastic modulus. See modulus of elasticity.

gradient across the double layer that is called the

zeta potential. The diagram is an approximation of

elastin. A scleroprotein that occurs in connective

this phenomenon. Modifications of this theory have

tissue.

been introduced in recent years, notably by Derja-

Properties: Yellow, fibrous mass. Insoluble in wa-

guin and Landau and by Verwey and Overbeek

ter, dilute acids, alkalies, salt solutions, and alcohol.

(DLVO theory).

Is partially digested by pepsin solution and wholly

See zeta potential.

by trypsin.

“ElastoFlo” [Dow]. TM for ethylene-propyl-

ene rubber polymer.

Properties: A free-flowing granular solid.

Use: For automotive hose, tubing and extrusions,

roofing membranes and gaskets.

“Elastoguard” [Milliken]. TM for an antimi-

crobial, anti-fatigue solution.

elastomer. As originally defined by Fisher

(1940), this term referred to synthetic thermosetting

493 ELECTRODE, GLASS

electric furnace. See furnace. electrical phenomena. It has certain applications in

biochemistry (in nerve reactions and the electric

organs of fish) as well as in organic chemistry. Mi-

electric steel. Steel made in an electric furnace.

chael Faraday (1791–1867) is generally regarded as

the founder of electrochemistry.

electric vehicle propulsion. See storage

battery.

electrocoating. A process of applying primer

paint to household appliances, automobiles, etc., in

electride. An experimental compound composed

which the metal piece to be coated becomes the

of an alkali-metal cation and an electron in which the

anode in a tank of water-based paint. The coating

electron functions as a chemical element (e.g., a

deposited on the metal is uniform regardless of the

halogen) in salt formation. Several such compounds

shape of the article. Large-scale use of electrocoat-

have been made in the U.S. and abroad. The phe-

ing is on automobile bodies.

nomenon is reported to be one that challenges ac-

See electrostatic coating.

cepted concepts of compound formation.

electroconductive polymer. See polymer,

electrochemical equivalent. The number of

electroconductive.

grams of an element or group of elements liberated

by the passage of one coulomb of electricity (one

ampere for one sec).

electrocratic. Descriptive of a liquid colloidal

dispersion of insoluble solid particles whose stabili-

ty is maintained by either positive or negative

“Electrocarb” [Electro Abrasives]. TM for

charges on the particles. As the like charges are

silicon carbide.

mutually repellent, they offset the attraction of grav-

CAS: 409-21-2.

ity and prevent the particles from sinking or coalesc-

Properties: High thermal conductivity, abrasion re-

ing. A colloidal gold suspension is a well-known

sistant, high hardness (2550 knoop). Electrical con-

example. Electrocratic dispersions can be readily

ductor.

precipitated by addition of an oppositely charged

Grade: Grit sizes 8–1600 mesh.

electrolyte, as in the purification of water with

Use: Wear resistant filler, thermal conductor in com-

ions from aluminum sulfate.

pounds, high temperature paints, ceramics, refracto-

ries. As a polishing and lapping abrasive.

“Electrocure.” TM for a process for hardening

electrochemical gradient. The sum of the gra- or curing paint films on plastics by use of low-volt-

dients of concentration and of electric charge of an age electron beams. Paints so treated cure in four sec

ion across a membrane. Used as the driving force for or less at room temperature; the finishes produced

processes, such as oxidative phosphorylation and are said to be superior in resistance to abrasion and

photophosphorylation. chemicals. The process can also be applied to other

substrates such as wood, glass, metals, etc.

electrochemical potential. The energy re-

quired to maintain a separation of charge and of

electrode. Either of two substances having differ-

concentration across a membrane.

ent electromotive activity that enables an electric

current to flow in the presence of an electrolyte.

Electrodes are sometimes called plates or terminals.

Electrochemical Society. (ECS). Established

Commercial electrodes are made of a number of

in 1902, this society was organized to promote the

materials which vary widely in electrical conductiv-

advancement of the science of electrochemistry and

ity, i.e., lead, lead dioxide, zinc, aluminum, copper,

related fields. It comprises 11 divisions, each devot-

iron, manganese dioxide, nickel, cadmium, mercu-

ed to a special branch of electrochemistry, e.g., cor-

ry, titanium, and graphite; research electrodes may

rosion, batteries, rare metals, electrodeposition, etc.

be calomel (mercurous chloride), platinum, glass, or

It publishes a journal and sponsors books relating to

hydrogen. Electrodes are essential components of

its major interests. Its office is at 65 South Main

both batteries and electrolytic cells; in batteries the

Street, Pennington, New Jersey 08534-2839.

negative plate is the anode and the positive plate the

Website: http://www.electrochem.org.

cathode, whereas in electrolytic cells the reverse is

the case.

electrochemistry. That branch of chemistry

Use: Electrodes are also used in welding devices.

concerned primarily with the relationship between

See anode; cathode; battery; electrolytic cell.

electrical forces and chemical reactions. This rela-

tionship is fundamental and farreaching, as the

structure of matter is based on electrical effects.

electrode, glass. A thin, glass membrane that

Electrochemistry is directly involved in chemical when immersed in a suitable liquid medium devel-

bonding, ionization, electrolysis (e.g., production of ops a measurable electrical potential that can be

aluminum), metallurgy, battery science, fuel cells, readily related to the activity of ionic species present

and corrosion—in short, in any situation in which a in the solution. By appropriate manipulation of the

chemical change is caused by or associated with glass composition, careful pretreatment of the glass

494ELECTRODE, HYDROGEN

surface, and reproducible experimental conditions, in a bath without application of an electric current,

i.e., by chemical reduction.

electrodes can be devised that not only yield infor-

mation about the concentration of ions in solution

but also have the ability to discriminate in the sense

electroluminescence. Luminescence generated

of a selective response between a number of differ-

in crystals by electric fields or currents in the ab-

ent ions of similar chemical characteristics. Because

sence of bombardment or other means of excitation.

of their ability to give both qualitative and quantita-

It is a solid-state phenomenon involving p- and n-

tive information about ions in solution, glass elec-

type semiconductors, and is observed in many crys-

trodes are widely used for purposes of chemical

talline substances, especially silicon carbide, zinc

measurement, especially in electrochemical re-

sulfide, and gallium arsenide, as well as in silicon,

search.

germanium, and diamond.

See phosphor.

electrode, hydrogen. A platinum surface coat-

electrolysis. Decomposition of water and other

ed with platinum black immersed in a solution and

inorganic compounds in aqueous solution by means

bathed with a stream of pure hydrogen gas. The

of an electric current, the extent being proportional

potential developed depends on the equilibrium be-

to the quantity of electricity passing through the

tween the hydrogen gas and the hydrogen ions in

solution. The positive and negative ions formed are

solution.

carried by the current to the oppositely charged

Use: Standard reference electrode.

electrodes, where they are collected (if wanted) or

released (if unwanted). Metallic ions deposited on

electrodeposition. The precipitation of a mate-

the electrode form a coating. A simple electrolysis is

rial at an electrode as the result of the passage of an

the separation of water into oxygen and hydrogen;

electric current through a solution or suspension of

this is one method of producing hydrogen. Some-

the material, for example, alkaline-earth carbonates,

what more complicated is electrolysis of brine to

rubber from latex, paint films on metal. A technique

chlorine and sodium hydroxide; this is carried out in

for electrodepositing refractory carbide coatings on

electrolytic cells of the diaphragm or mercury type,

metal has been reported. The electrode is in the

with water taking part in the reaction. In electroplat-

shape of the desired article. An important advantage

ing, metal salts dissociate into their constituent ions,

of electrodeposition is its ability to coat complex

the positively charged metal ions coating the cath-

shapes having small and irregular cavities with exact

ode. There are a number of variations of this process

thickness control.

(electrodeposition, electrocoating, electroforming).

See electrophoresis.

See electrolytic cell; ionization.

electrodialysis. A form of dialysis in which an

electrolyte. A substance that will provide ionic

electric current aids the separation of substances that

conductivity when dissolved in water or when in

ionize in solution. Seawater can be desalted by this

contact with it; such compounds may be either solid

method on a large scale by placing it in the center

or liquid. Familiar types are sulfuric acid and sodi-

chamber of a three-compartment container having

um chloride, which ionize in solution. One solid

two semipermeable membranes and a positive elec-

electrolyte, used originally in fuel cells, is a polymer

trode in one end chamber, and a negative electrode

of perfluorinated sulfonic acid used as the core of a

in the other. The ions migrate to their respective

water electrolysis cell for production of hydrogen

electrodes under a difference of potential, leaving

and oxygen. When saturated with water it has high

the water saltfree.

conductivity. Another solid type is a ceramic mix-

See dialysis; desalination; demineralization.

ture of sodium, aluminum, lithium, and magnesium

used as a separating medium in the liquid-sodi-

electroforming. An electrolytic plating process

um–sulfur (␤) battery under continuing develop-

for manufacturing metal parts. A mold of the object

ment. The most common application of electrolytes

to be reproduced is made in a soft metal or in wax (by

is in electroplating of metals in which dissolved

impression). The mold surface is made conducting

(ionized) metal salts are the electrolytes.

by coating with graphite. Some suitable metal is

See electrolysis; electroplating.

then deposited electrolytically on the mold surface.

This mold is then (in most cases) a negative of the

electrolyte acid. Legal label name for battery

object to be produced. Other industrial applications

acid.

are phonograph records, plastic tile, ducting, tubing,

etc.

electrolytic cell. An electrochemical device in

which electrolysis occurs when an electric current is

electrogenic. Contributing to the generation of

passed through it. Ionizable compounds dissociate

an electrical potential across a membrane.

in the aqueous solution with which the electrodes are

in contact. Such cells are of two types: (1) the dia-

electroless coating. A protective coating of phragm cell, which has two compartments separated

copper, cobalt, nickel, gold, or palladium deposited by a porous membrane; and (2) the mercury cell, in

495 ELECTRONEGATIVITY

which mercury is the cathode. The anodes of both tric energy, or bombardment with high-energy parti-

types have long been made of graphite; because this cles (see radiation, ionizing). In such cases, they are

decomposes rapidly as electrolysis progresses, they totally free from the atomic orbit and their energy

are being replaced with dimensionally stable types can be utilized by means of a conductor (electricity)

consisting of titanium coated with oxides of rutheni- or a vacuum tube or semiconductor. Current is gen-

um and other rare metals, which are also much more erated by detaching the electrons of a metallic con-

efficient. In electrolysis of sodium chloride, the cur- ductor (silver, copper) by means of an electric or

rent causes chloride ion to migrate to the anode, magnetic field; the electrons then flow along the

where it is collected as chlorine gas; sodium hydrox- conductor to a positively charged terminal. The sci-

ide and hydrogen are also formed, the hydrogen ence of electronics was made possible by the ability

being discharged. The overall cell reaction is: 2NaCl of a heated metal cathode to emit a continuous

+2H

O → H

+Cl

+ 2NaOH. This principle is stream of electrons in a vacuum tube. Free electrons,

applied in the electroplating of metals, electrodepo- called ␤ particles, are spontaneously emitted by de-

sition of colloids, and similar processes. caying radioactive nuclei; they have comparatively

See diaphragm cell; mercury cell; electroplating. low energy but can be accelerated to velocities ap-

proaching that of light. The basic nature of the elec-

tron has been the subject of much research of the

electromagnetic separation. Separation of

highest order of mathematical rigor. In simplest

isotopes, especially those of uranium, by first accel-

terms, the electron has the properties of both a parti-

erating them by means of an electrostatic field and

cle and a wave, i.e., a standing wave is associated

then passing them through a magnetic field. The

with an electron moving in its orbit. The energy state

effect of this is to cause all the particles to take a

of any electron in an atom is described by four

curved path; the heavier ones, having higher kinetic

quantum numbers.

energy, describe a wider arc than the lighter ones.

See shell; atom; orbital theory; Lewis electron theory.

Thus, two isotopes of closely similar masses can be

separated and collected.

See mass spectrometry; magnetic separation.

electron acceptor. A substance that receives

electrons in a redox reaction.

electromagnetic spectrum. See radiation.

electron-beam welding. See welding.

electrometallurgy. Application of the princi-

ples and techniques of electrochemistry to the pro-

electron carrier. A protein or other chemical

duction of such metals as aluminum and titanium. species, such as a cytochrome or coenzyme Q, that

can reversibly gain and lose electrons. They func-

tion in the transfer of electrons from organic nutri-

electromotive series. See activity series.

ents to oxygen or some other terminal acceptor as in

the case of anaerobes.

electron. Discovered by J. J. Thompson in 1896,

the electron is a fundamental particle of matter that

electron donor. A substance that donates elec-

can exist either as a constituent of an atom or in the

trons in a redox reaction.

free state. It has a negative electric charge (4.8 × 10

−10

esu) and a mass 1/1837 that of a proton, equivalent to

9.1 × 10

−28

gram. The number of electrons in an atom electronegativity. All atoms (except those of

of any element is the same as the number of protons helium) that have fewer than eight electrons in their

in the nucleus, i.e., the atomic number. Thus, the highest principal quantum level have low-energy

range is from one electron in hydrogen to 103 in orbital vacancies capable of accommodating elec-

lawrencium. As the negative charge of the electrons trons from outside the atom. The existence of these

equals the positive charge of the protons, all atoms vacancies is evidence that within these regions the

are electrically neutral. Electrons are arranged in nuclear charge can exert a significant attraction for

from one to seven shells around the nucleus; the such electrons, even though as a whole the atom is

maximum number of electrons in each shell is strict- electrically neutral. This attraction is called “elec-

ly limited by the laws of physics. The tendency of tronegativity.” To the extent that the initially neutral

electrons to form complete outer shells accounts for atom may be able to acquire electrons from outside,

the valence of an element, and they play an essential it will acquire also their negative charge. The word

part in chemical bonding. The outer shells are not “electronegativity” means “tendency to become

always filled: sodium has two electrons in the first negatively charged.” The concept of electronegativ-

shell, eight in the second, and only one in the third. A ity is an extremely useful one in chemistry, since the

single electron in the outer shell may be attracted attractive force exerted by the nuclei of atoms that

into an incomplete shell of another element, leaving have vacancies in their outer shells makes possible

the original atom with a net positive charge. Each the formation of both covalent and ionic bonds and

atom then is called an ion. Valence electrons are is thus a fundamental factor in the formation of

those that can be captured by or shared with another chemical compounds. The most highly electronega-

atom. Electrons can be removed from the atoms of tive elements are the halogens, sulfur, and oxygen.

metals and some other elements by heat, light, elec- See bond, chemical.

496ELECTRON MICROSCOPE

electron microscope. A microscope in which Use: In recombinant DNA technology.

See transfection.

the source of illumination is a stream of electrons

emanating from a tungsten cathode in a high vacuum

and accelerated by a strong electric impulse (300

electron transport chain. See acceptor con-

kv). The electrons are focused by a series of magnet-

trol.

ic fields that function as lenses in the same way as

glass affects waves of visible light, i.e., the electron

electron-volt. (eV). An extremely small unit

stream curves as it passes through the magnetic

used in measuring the energy of electrons and other

field. Such lenses were developed in Germany by

atomic constituents. It is the energy developed by an

Busch, Knoll, and Tuska in the 1930s, and were

electron in falling through a potential difference of

adapted to microscopy by Zworykin and Hillier at

one V, equivalent to 1.6 × 10

−19

J. The rupture of a

the RCA Laboratories in the early 1940s, when the

carbon-to-carbon bond has been calculated to yield

first commercial instruments were produced. The

approximately 5 eV.

electron microscope is characterized by extremely

high resolving power due to the ultrashort wave-

electrophoresis. Migration of suspended or col-

length of electronic radiation—a small fraction of an

loidal particles in a liquid such as rubber latex due to

angstrom unit (A

). Resolution of 2 A

is possible,

the effect of a potential difference across immersed

which permits determination of the structure of mac-

electrodes. The migration is toward electrodes of

romolecules (DNA) and even observation of large

charge opposite to that of the particles. Most solids,

atoms (uranium). Instruments of the scanning trans-

being negatively charged, migrate to the anode, the

mission type with a resolving power of 0.05 A

were

exception being basic dyes, hydroxide solutions,

developed at the University of Chicago. Two kinds

and colloids that have adsorbed positive ions, all of

of electron microscopies are in general use: the

which are positively charged and migrate to the

transmission type, in which the electrons penetrate

cathode. Migrating particles lose their charge at the

the specimen, and the scanning type introduced in

electrode and generally agglomerate around it. Clay

1970, in which the electrons, condensed to a fine

suspensions can be filtered by means of forced-flow

beam, repeatedly traverse the surface of the speci-

electrophoresis. Electrophoresis is important in the

men, producing a three-dimensional contour effect

study of proteins because the molecules of such

by means of secondary electrons emanating from the

materials act like colloidal particles and their charge

specimen itself. Pictures of astonishing accuracy

is positive or negative according to whether the

have been obtained, especially of surface structures,

surrounding solution is acidic or basic. Thus, the

a matter of great importance in the study of catalysis

acidity of the solution can be used to control the

and other critical phenomena in both industry and

direction in which a protein moves upon electropho-

the biological sciences. A unique combination of

resis. It has been found that electrophoresis can be

these techniques is the scanning transmission elec-

carried out more efficiently under zero-gravity con-

tron microscope (STEM), by means of which col-

ditions in outer space than on earth.

ored motion pictures of uranium atoms on a thin-

Use: Experimentally to separate mixtures of electri-

film carbon substrate have been obtained.

cally charged species such as proteins or nucleic

See optical microscope; resolving power; ultramicro-

acids.

scope; field-ion microscope.

See electrodeposition.

electroplating. The deposition of a thin layer or

electron octet. Group of eight valence elec-

coating of metal (e.g., chromium, nickel, copper,

trons. The most stable configuration of the outer-

silver, etc.) on an object by passing an electric cur-

most, or valency, electron shell of the atom.

rent through an aqueous solution of a salt containing

ions of the element being deposited, for example,

electron paramagnetic resonance. (EPR).

. The material being plated (usually a metal but

A method of spectroscopic analysis similar to nucle-

often a plastic) constitutes the cathode. The anode is

ar magnetic resonance except that microwave radia-

often composed of the metal being deposited; ideal-

tion is employed instead of radio frequencies. It is

ly it dissolves as the process proceeds. The thin layer

used for studying free radicals, crystalline centers,

deposited is sometimes composed of two or more

transition elements, and structures involving un-

metals, in which case it is an alloy. The solution or

paired electrons.

plating bath contains dissolved salts of all the metals

being deposited. Electrolytic cells are used for this

electrophile. An electron-deficient group with a

process. The anode must be an electrical conductor,

strong tendency to accept electrons from an elec-

but may or may not be of the same chemical compo-

tron-rich group (nucleophile).

sition as the material being deposited, and may or

See nucleophile; Lewis acid.

may not dissolve during the process. The purpose of

electroplating is usually protection of the base metal

electroporation. A process using high-voltage from corrosion. Silver is electroplated on copper for

current to make cell membranes permeable to allow economy reasons; plastics may be electroplated for

the introduction of new DNA. decorative effects.

497 ELUATE

See electrophoresis; protective coating; “electroless” heavier than lead are unstable and radioactive.

About 90% of the earth’s crust is made up of ele-

coating; throwing power; current density.

ments with even numbers of protons and neutrons.

No stable elements heavier than nitrogen have an

electropolishing. A nonmechanical method of

odd number of both protons and neutrons. Elements

polishing metal surfaces that is actually the reverse

of even atomic number normally have several iso-

of electroplating. This is achieved by making the

topes, while those of odd atomic number never have

object to be polished the anode in an electrolytic

more than two stable isotopes. All elements beyond

circuit, the cathode usually being carbon. The elec-

uranium (transuranic) were nonexistent in 1940.

trolytes used are phosphoric, hydrofluoric, nitric,

They are artificially created by bombardment of

and sulfuric acids (sometimes called polishing

other elements with neutrons or other heavy parti-

acids).

cles. Research on new elements is actively carried

on at many laboratories including the Lawrence

electrostatic bond. Alternative name for an

Livermore Laboratories, which reported discovery

ionic bond.

of element 106 in 1974. Creation of element 109 was

See bond, chemical.

announced in 1982, and of element 112 in 1996. A

single atom of element 109 was made by West Ger-

electrostatic coating. A metal-painting tech-

man physicists by bombarding

209

Bi with

Fe nuclei.

nique in which electrostatically charged pigment

Controversy continues on the naming of elements

particles are sprayed onto a substrate metal, fol-

104 through 109. Many more (possibly up to 150)

lowed by baking. The electric charge attracts the

are theoretically possible according to Dr. G. T.

particles to the metal and holds them in place until

Seaborg.

heat treatment is applied. Maintenance of the charge

See periodic table; isotope; radioactivity; abundance.

is thus essential; factors affecting this are relative

Note: For origin of elements, see nucleogenesis.

humidity (the lower the better) and the chemical

nature of the pigment, e.g., phthalocyanine blue

retains the charge much longer than titanium di-

elemi. A soft, balsam like resin obtained from a

oxide.

tree in the Philippines, soluble in coal tar hydrocar-

bons, but not in petroleum solvents, alcohols, and

electrostatic precipitator. See Cottrell,

ketones.

Frederick G.

Use: Plasticizer, adhesion of lacquers to metals, ce-

ments and adhesives, wax compositions, printing

electrovalent bond. Alternative name for an

inks, textile and paper coatings, perfumery, water-

ionic bond.

proofing, engraving.

See bond, chemical; ionic bond.

elimination reaction. A chemical reaction in-

electrowinning. The technique of extracting a

volving elimination of a portion of a reactant com-

metal from its soluble salt by an electrolytic cell. It is

pound, resulting in a second compound. Many reac-

used in recovery of zinc, cobalt, chromium, and

tions eliminate water.

manganese, and has been applied to copper when in

the form of a silicate ore. For any specific metal, the

“Elimin-Ox” [Nalco]. TM for chemicals for

salt in solution is subjected to electrolysis and is

scavenging oxygen.

electrodeposited on a cathode made of the metal

Use: In water systems.

being extracted.

element. One of the 112 presently known kinds of

elongation factors. Specific proteins required

substances that compose all matter at and above the

in the elongation of polypeptide chains by ribo-

atomic level. According to a theory that has gained

somes, or DNA strands by replisomes.

acceptance, the lightest elements were formed in

less than half an hour from a primordial complex

Eltekoff reaction. Production of highly

called ylem, a mixture of neutrons and electromag-

branched hydrocarbons by methylation of olefins

netic radiation. The smallest unit of any element is

with methyl choride, or methyl iodide in the pres-

the atom. All the atoms of a given element are

ence of lead oxide, or calcium oxide at high tempera-

identical in nuclear charge and number of electrons

tures.

and protons, but they may differ in mass, e.g., hydro-

gen has mass numbers of 1, 2, and 3, called hydro-

eluant. The liquid used to separate or extract one

gen, deuterium, and tritium, respectively. These are

material from another.

the isotopes of hydrogen; most elements have isoto-

See chromatography.

pic forms that are due to the presence of one or more

extra neutrons in the nucleus. The atomic number of

an element indicates its position in the periodic table

eluate. The solution that results from the elution

and represents the number of protons present, which process.

is the same as the number of electrons. All elements See chromatography.

498ELUTRIATION

elutriation. A process of washing, decantation, Hazard: Toxic by ingestion.

and settling that separates a suspension of a finely

divided solid into parts according to their weight. It

emeralds, synthetic. Artificial crystals pro-

is especially useful for very fine particles below the

duced by a high-pressure, high-temperature process

usual screen sizes, and is used for pigments, clay

from beryllium aluminum silicate containing a

dressing, and ore flotation.

small amount of chromium.

Use: Lasers, masers, semiconductors.

“Elvace” [Reichhold]. TM for a series of vinyl

acetate ethylene emulsions.

emery. See corundum; abrasive.

“Elvacite” [Du Pont]. (butyl methacrylate emetine. (cephaeline methyl ether; 6

′

,10,11-

tetramethoxyemetan).

resins). TM for polymer products.

CAS: 483-18-1. C

. An alkaloid from

Use: Resistance to UV weathering and degrading; as

ipecac.

base for lacquers, paints, coatings, and inks.

Properties: White powder; very bitter taste. Mp 74C.

Darkens on exposure to light. Soluble in alcohol and

“Elvanol” [Du Pont]. TM for various grades

ether, slightly soluble in water.

of polyvinyl alcohol.

Derivation: By extraction from root of Cephalis ipe-

cacuanha (ipecac) or synthetically.

“EMA” resins [Solutia]. TM for ethylene-

Hazard: Toxic by ingestion.

maleic anhydride copolymers. Water-soluble resins

Use: Medicine (antiamebic).

that serve as dispersing agents in cold-water deter-

gents, thickeners, binders, stabilizers, and emulsi-

emission spectroscopy. Study of the composi-

fiers.

tion of substances and identification of elements by

observation of the wavelengths of radiation they

embosser. See fiber roll.

emit as they return to a normal state after excitation

by an external energy source. When atoms or mole-

embrittlement. Hardening of a metal (especially

cules are excited by energy input from an arc, spark,

steel) or of an ABS resin, resulting in loss of strength

or flame, they respond in a characteristic manner;

and impairment of other physical properties. In met-

their identity and composition are signaled by the

als, the primary cause is exposure to hydrogen,

wavelengths of incident light they emit. The spectra

though other factors such as corrosion also are in-

of elements are in the form of lines of distinctive

volved. In copolymer plastics, such as ABS resins,

color, such as the yellow sodium D line of sodium;

embrittlement is due to formation of a vitreous ma-

those of molecules are groups of lines called bands.

trix as well as to oxidation of the butadiene particles

The number of lines present in an emission spectrum

in the matrix. Embrittlement due to thermal shock

depends on the number and position of the outer-

occurs in pressurized-water reactors. This may re-

most electrons and the degree of excitation of the

sult in rupture of reactor walls and is a constant

atoms. The first application of emission spectra was

source of trouble in reactors of this type.

identification of sodium in the solar spectrum

(1814).

embryo. Once a zygote begins to undergo cellular

See spectroscopy.

divisions, it becomes an embryo.

emivirine.

embryonic stem (ES) cells. An embryonic

CAS: 149950-60-7. mf: C

cell that can replicate indefinitely, transform into

Hazard: Moderately toxic by ingestion.

other types of cells, and serve as a continuous source

of new cells.

emmenagogue. A drug used to induce menstrua-

tion.

Emde degradation. Modification of the Hof-

mann degradation method for reductive cleavage of

the carbon-nitrogen bond by treatment of an alco-

Emmert reaction. Formation of 2-pyridyldial-

holic or aqueous solution of a quaternary ammo- kylcarbinols by condensation of ketones with pyri-

nium halide with sodium amalgam. Also used as a dine or its homologs in the presence of aluminum or

catalytic method with palladium and platinum cata- magnesium amalgam.

lysts. The method succeeds with ring compounds

not degraded by the Hofmann procedure.

emodin. (frangula emodin; frangulic acid;

1,3,8-trihydroxy-6-methylanthraquinone).

emedastine difumarate.

CAS: 518-82-1. C

(OH)

CAS: 87233-62-3. mf: C

O•2C

Occurrence: Either free, or combined with a sugar in

Hazard: A poison by ingestion.

a glucoside, in rhubarb, cascara sagrada, and other

plants. A synthetic product is also available.

emerald green. A pigment consisting of copper Properties: Orange crystals. Mp 256C. Soluble in

acetoarsenite. alcohol, insoluble in water.

499 ENANTIOMER

Use: Medicine (cathartic). ules plus water droplets are the disperse phase.

See colloid; protective; phase (2); detergent; surface-

active agent; wetting agent.

emoren.

CAS: 13930-31-9. mf: C

•xClH.

Hazard: Moderately toxic by ingestion.

emulsion breaker. See demulsification.

empirical formula. See formula, chemical.

emulsion paint. See paint emulsion.

EMTS. Abbreviation for ethylmercury-p-toluene

emulsion polymerization. Polymerization re-

sulfonanilide.

action carried out with the reactants in emulsified

form. Performed at normal pressure and −20 to

“Emulmetik” [Lucas Meyer]. TM for hy-

+60C. Many copolymers (synthetic rubbers) are

drogenated lecithin.

made in this way.

emulsifier. A surface-active agent.

“Emulsiphos” [Solutia]. TM for sodium

See emulsion.

phosphate.

CAS: 7601-54-9.

emulsifying oil. See soluble oil.

Grade: Powders.

Use: Food-grade phosphate emulsifying agent used

“Emulsilac-S” [ACH]. (sodium stearoyl lac-

in processed cheese and cheese food.

tylate) TM for emulsifier, dough conditioner-

strengthener, and whipping agent.

“Emulvis” [Hall]. TM for polyoxyethylene

Use: For baked goods, puddings, dips, cheese substi-

stearate.

tutes, sauces, whipped toppings, and fillings.

Use: Viscosity builder and solubility retarder for cos-

metics, soaps, and shampoos.

emulsion. (synaptase; amygdalase; ␤-glucosi-

dase). An enzyme catalyzing the production of glu-

en. Abbreviation for ethylenediamine, used in for-

cose from ␤-glucosides.

mulas for coordination compounds, e.g., the cobalt

Properties: White powder; odorless; tasteless. Capa-

complex Co[en]

(NO

)

ble of hydrolyzing glucosides such as amygdalin to

See dien; pn; py.

glucose and the other component substances. Solu-

ble in water; insoluble in ether and alcohol.

enamel. (1) A type of paint consisting of an inti-

Source: Sweet almonds.

mate dispersion of pigments in a varnish or resin

Derivation: By extracting an emulsion of almonds

vehicle. The vehicle may be an oil-resin mix or

with ether, filtering the clear solution, and precipi-

entirely synthetic resin. Those containing drying

tating the emulsion with alcohol.

oils are converted to films by oxidation; those com-

posed wholly of synthetic resins may be converted

emulsion. A stable mixture of two or more im-

by either heat or oxidation, or both.

miscible liquids held in suspension by small per-

See baking finish.

centages of substances called emulsifiers. These are

(2) Porcelain enamel.

of two types: (1) Proteins or carbohydrate polymers

which act by coating the surfaces of the dispersed fat

enamine. A group of amino olefins; the name

or oil particles, thus preventing them from coalesc-

refers especially to unsaturated tertiary amines of

ing; these are sometimes called protective colloids.

the general formula

(2) Long-chain alcohols and fatty acids, which are

able to reduce the surface tension at the interface of

the suspended particles because of the solubility

properties of their molecules. Soaps behave in this

where R is any alkyl group. Though of little use as end

manner; they exert cleaning action by emulsifying

products, enamines are valuable intermediates for

the oily components of soils. All such substances,

many organic syntheses.

both natural and synthetic, are known collectively as

detergents. Polymerization reactions are often car-

enanthaldehyde. See heptanal.

ried out in emulsion form; a wide variety of food and

industrial products are emulsions of one kind or

enanthic acid. See n-heptanoic acid.

another, e.g., floor and glass waxes, drugs, paints,

shortenings, textile and leather dressings, etc. All

enanthyl alcohol. See heptyl alcohol.

emulsions consist of a continuous phase and a dis-

perse phase: in an oil-in-water (o/w) emulsion, such

as milk, water is the continuous phase and butterfat

enantiomer. (enantiomorph). One of a pair of

(oil) the disperse phase; in a water-in-oil (w/o) emul- optical isomers containing one or more asymmetric

sion, such as butter, free fat (from crushed fat glob- carbon atoms C* whose molecular configurations

ules) is the continuous phase and unbroken fat glob- have left- and right-hand (chiral) forms. These

500ENANTIOMORPH

forms are conventionally designated dextro (

D) and endocytosis. The uptake of extracellular material

by its inclusion within a vesicle (endosome) formed

levo (

L) because they compare to each other structur-

by an invagination of the plasma membrane.

ally as do the right and left hands when the carbon

atoms are lined up vertically. This is apparent in the

endoergic. See Endothermic.

enantiomorphic forms of glyceraldehyde; the two

structures are mirror images of each other and can-

endomycin. An antifungal antibiotic complex

not be made to coincide:

produced by streptomyces.

endonuclease. An enzyme that digests nucleic

acids starting in the middle of the strand (as opposed

to an exonuclease, which must start at an end). Ex-

Several pairs of enantiomers are possible, depending

amples include the restriction enzymes, DNase I and

on the number of asymmetric carbon atoms in the

RNase A.

molecule. Compounds in which an asymmetric carbon

See restriction enzyme.

is present display optical rotation.

See asymmetry; optical isomer; optical rotation.

endoplasmic reticulum. An extensive system

of double membranes in the cytoplasm of eukaryotic

enantiomorph. See enantiomer.

cells. The two major types are smooth and rough

endoplasmic reticulum. Functions in calcium stor-

encapsulation. The process in which a material

age as well as in protein and lipid synthesis.

or an assembly of small, discrete units is coated with

or imbedded in a molten film, sheath, or foam, usual-

“Endor” [Du Pont]. TM for a rubber peptiz-

ly of an elastomer. A foam-forming plastic may be

ing agent containing activated zinc salt of pentachlo-

used to fill the spaces between various electrical or

rothiophenol. (C

Zn and 80% inert filler.

electronic components so that they are imbedded in

Properties: Grayish-green powder. D 2.39.

and supported by the foam. Plastics and other mate-

rials used for this purpose are often called potting

endorphin. Any of a group of polypeptides

compounds. A specialized use of this technique is in

formed in the brain tissue and pituitary gland of

growing crystals for semiconductors, in which a

higher animals that are thought to control the trans-

coating of liquid boric oxide is the encapsulating

fer of signals at nerve junctions, thus ensuring that

agent. Use of a glassy silicate coating to encapsulate

behavior patterns in the individual remain normal.

nuclear waste for permanent disposal is under inves-

Imbalance or malfunction of these polypeptides has

tigation.

been reported to be a factor in irrational and violent

See microencapsulation.

actions and other emotional disorders, as well as in

epilepsy and memory processes. This belongs to a

′

end. The end of a nucleic acid that lacks a

developing field of medicinal chemistry called neu-

nucleotide bound at the 3

′

position of the terminal

ropharmacology.

residue.

␤-endorphin.

endergonic reaction. A chemical reaction that

CAS: 60617-12-1.

consumes energy (that is, for which DG is positive).

Hazard: A reproductive hazard.

This is a nonspontaneous processe.

endosmosis. The passing of a fluid inward

“Endic” anhydride [Velsicol]. TM for

through a porous partition toward another fluid of

endo-cis-bicyclo(2.21)-5-heptene-2,3-dicarboxylic

different character.

anhydride. (C

See exosmosis; Perrin rule.

Properties: White crystals. Mp 163C. Soluble in

aromatic hydrocarbons, acetone, ethanol.

endosulfan. (6,7,8,9,10,10-hexachloro-

Use: Elastomers, plasticizers, fire retardant chemi-

1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzo-

cals, resins, and epoxy curing systems.

dioxathiepin-3-oxide).

CAS: 115-29-7. C

endo-. A prefix used in chemical names to indi-

Properties: (commercial product): Brown crystals.

cate an inner position, specifically (1) in a ring rather

Mp 70–100C (pure: mp 106C). Mixture of two iso-

than a side chain or (2) attached as a bridge within a

mers. Mp 108–109C and 206–208C.

ring.

Hazard: Toxic by ingestion, inhalation, and skin

See exo-.

absorption; use may be restricted. TLV: 0.1 mg/m

;

not classifiable as a human carcinogen.

Use: Insecticide.

endocrine glands. Groups of cells specialized

to synthesize hormones and secrete them into the

blood to regulate other types of cells. The pancreas,

endosymbiosis. When one organism takes up

for example. permanent residence within another, so that the two

501 ENERGY BALANCE

become a single functional organism. Mitochondria

enercology. A coined word defined as the bal-

and plastids are believed to have resulted from endo- anced relationship between energy and ecology. A

symbiosis. foundation devoted to practical applications of this

relationship has been established at Alma College,

Michigan.

endothall. (7-oxalobicyclo-[2.2.1]-heptane-2,3-

dicarboxylic acid disodium salt).

CAS: 145-73-3. C

Ene reaction. Addition of an olefin with an

Hazard: Strong irritant to eyes and skin.

allylic hydrogen (ene) to a compound with a double

Use: Defoliant, herbicide.

bond (enophile), involving the allylic shift of one

double bond, transfer of the allylic hydrogen to the

endothermic. A process or change that takes

enophile, and bonding between the two unsaturated

place with absorption of heat and requires high tem-

termini.

perature for initiation and maintenance. An example

is production of carbon monoxide and hydrogen by

energy. The fundamental active entity in the uni-

passing steam over hot coke.

verse, defined as the capacity for doing work. Two

famous equations relate energy to mass as either E

endothion. [S-(5-methoxy-4-oxo-4H-pyran-2-

(Einstein) or E

h␤n (Planck). These equations

yl)-methyl] O,O-dimethylphosphorothioate).

show that energy cannot be completely divorced

CAS: 2778-04-3.

from mass, as the two are to some extent intercon-

vertible. The law of conservation of energy, simply

stated, is that the sum total of energy in the universe

(CH

P(O)SCH

❘

:CHC(O)C(OCH

):CH

❘

is constant; therefore, energy cannot be either creat-

Properties: Crystals. Mp 90–91C. Very soluble in

ed or destroyed, but only converted from one form to

water; soluble in chloroform and ethanol.

another. Radiant energy (light) comprises the elec-

Hazard: Toxic by ingestion, cholinesterase inhibi-

tromagnetic spectrum; all wavelengths of light are

tor; use may be restricted.

composed of photons or packets of energy traveling

Use: Insecticide.

at the speed of light. Theoretically, they have no

mass except that associated with their speed. Pro-

end point. (1) In chemical analysis, the point

tons, electrons, and neutrons are forms of highly

during a titration at which a marked color change is

condensed energy that possess determinable mass

observed, indicating that no more titrating solution

but move at lower speeds. Energy is directly related

is to be added.

to chemical phenomena in the formation and decom-

See indicator. (2) The highest temperature reached

position of compounds, in the many important reac-

during an assay distillation of hydrocarbon liquids,

tions that occur in electrochemistry, and in the re-

indicating the overall volatility of the liquid

lease of energy in nuclear fission and fusion. Free

(ASTM).

energy is a thermodynamic function; in chemical

reactions, it is a measure of the extent to which a

end-product inhibition. Inhibition of an allo-

substance can react. Kinetic energy (the energy of

steric enzyme at the beginning of a metabolic se-

motion) is most clearly exhibited in gases, in which

quence by the end product of the sequence.

molecules have much greater freedom of motion

than in liquids and solids.

endrin. (1,2,3,4,10,10-hexachloro-6,7-epoxy-

See radiation; matter; thermodynamics; free energy.

1,4,4a,5,6,7,8,8a-octahydro-1,4-endo,endo-5,8-di-

Note: “One of the most difficult challenges we face is

methanonaphthalene).

to find ways to ensure that all peoples of the world

CAS: 72-20-8. C

OCl

. A stereoisomer of dield-

share more equitably the vast human benefits that

rin which is the endo, exo isomer.

energy can bring. The foundation of worldwide en-

Properties: White, crystalline powder. Mp approxi-

ergy policy must be based on energy conservation

mately 200C (rearranges above this point). Insolu-

and the development of additional sources through a

ble in water and methanol; moderately soluble in

judicious application of science and technology.”

other common organic solvents; compatible with

(Glenn T. Seaborg, ACS meeting, April 1976).

nonacidic fertilizers, herbicides, fungicides, and in-

secticides.

energy, activation. The minimum energy

Hazard: Toxic by inhalation and skin absorption, a

which a molecule must acquire before it can be

carcinogen, use may be restricted. TLV: 0.1 mg/m

;

regarded as being activated. The difference between

not classifiable as a human carcinogen.

the energy of an activated molecule and the mean

Use: Insecticide.

energy of all the molecules.

See aldrin.

-ene. (1) Suffix denoting open-chain unsaturated energy balance. (1) Energy required to carry on

hydrocarbons having one double bond, as in pro- an operation or to maintain the desired operating

pene. (2) Suffix denoting an aromatic cyclic hydro- conditions. (2) Calculation of energy required to

carbon, as in benzene. balance a reaction.

502ENERGY BAND

energy band. Energy spectrum of valence elec- cellulose ocean thermal energy

coal oil sands

trons in a polyatomic material.

conversion peat

copaiba petroleum

energy charge. The fractional degree to which

ethyl alcohol (note) plutonium

the ATP/ADP/AMP system is filled with high-ener-

fission radiation

gy phosphate groups.

fuel cell shale oil

fuel oil solar cell

energy converter. Any element or compound

fusion solar energy

having the ability to convert the radiant energy of

gasification solar pond

sunlight into electrical, thermal, or chemical energy.

gasohol storage (4)

Prominent among them are silicon, selenium, and

gasoline thermoelectricity

tellurium, as well as the chlorophyll of plants in

geothermal energy uranium

photosynthesis.

guayule wood

See solar cell; magnetohydrodynamics.

energy coupling. The transfer of energy from

“Energy Smart” [Advanced Ingredients].

one process to another. For example, the coupling of

TM for a nutritive carbo sweetener made from

ATP hydrolysis with glucose phosphorylation.

fruit juice and dextrin.

Use: Nutritive sweetener that is stable at room tem-

energy gap. Forbidden part of energy spectrum

peratures.

of valence electrons.

energy storage. See storage (4).

energy level. See quantum state.

enfleurage. Extraction of odoriferous compo-

energy sources. Nonrenewable energy sources

nents of flowers by means of fats or mixtures of fat

are materials of geologic origin, i.e., petroleum, nat-

and tallow, the process being carried out at room

ural gas, coal, shale oil, and uranium, which cannot

temperature to avoid decomposition of the desired

be replaced once their supply is exhausted. Renew-

perfumes. The latter are separated from the fat by

able sources, on the other hand, are those that can be

washing with alcohol.

replenished on a predictable time basis and are

See essential oil; perfume.

known collectively as biomass; these include such

cellulosic products as wood, bagasse, agricultural

enflurane. (2-choro-1,1,2-trifluoroethyl difluo-

waste, and residue from the forest products indus-

romethyl ether).

tries (shavings, bark, sawdust, etc.), which yield the

CAS: 13838-16-9. C

ClF

same heating value per dry ton as one barrel of crude

Properties: Clear, colorless liquid; mild, sweet odor.

oil. Several of these sources have been in use for

Mw 184.50, D 1.5167 (25C), bp 56.5C, vap press

some years as on-site fuels in the sugarcane, ply-

174.5 mm Hg (20C). Soluble in organic solvents;

wood, and paper pulp industries. Another instance is

slightly soluble in water.

methane obtained from animal manures (biogas),

Hazard: Volatile with anesthetic properties, but non-

which is being developed on a large scale in the west

flammable. TLV: 75 ppm; not classifiable as a hu-

and southwest. Interest in the mass cultivation of

man carcinogen.

algae and hydrocarbon-producing plants such as

Use: Clinical anesthetic.

guayule and copaiba for fuel has been reported.

There are also a number of mechanical energy

engineering material. A metal, alloy, plastic,

sources whose development involves engineering

or ceramic used in the fabrication of machinery and

rather than chemistry, namely, solar radiation, wind,

its components, structural shapes, chemical process

water flow, tides, and thermal gradients in ocean

equipment, castings, tools, instruments, drums,

water. Several of these are already in limited opera-

tanks, piping, ductwork, and auxiliary items (ex-

tion, but in most cases their development will be

cluded are materials used chiefly as protective coat-

slow and costly. Hydroelectric power has long been

ings or as components of alloys). Engineering mate-

an accomplished fact, though it accounts for only

rials are characterized by hardness, strength,

about 1% of electrical needs. Solar energy is being

machinability, dimensional stability, nonflamma-

actively researched, but is unlikely to be a factor of

bility, and resistance to corrosion, most acids, sol-

consequence for at least another decade. The follow-

vents, and heat. The more important of these are

ing entries discuss the chemical sources of energy

listed below; for specific uses, see individual entries.

more specifically:

Metals and alloys Plastics

battery hydrocarbon (note)

biogas hydrogen aluminum ABS resin

biomass methane beryllium acetal resin

breeder natural gas brass acrylic resin

carbohydrate nuclear energy bronze fluorocarbon polymer

503 ENTRAINER

enolase. An enzyme active in glycolysis that cata-

Metals and alloys Plastics

lyzes the conversion of 2-phosphoglyceric acid to

cast iron nylon

the phosphorylated enol of pyruvic acid.

copper phenolformaldehyde resin

lead polybutylene terephthalate

enology. (oenology). The art and science of wine

magnesium polycarbonate

making.

steel polyethylene

tantalum polyphenylene oxide

“Enovid” [Searle]. TM for norethynodrel with

titanium polypropylene

mestranol. Oral contraceptive approved by FDA.

zinc polystyrene

zirconium polyvinyl chloride

enprostil.

various trademarked reinforced plastics (FRP)

CAS: 73121-56-9. mf: C

alloys

Hazard: Moderately toxic by ingestion.

ureaformaldehyde resin

Ceramics

enrichment. (1) In food technology, the addition

glass

to a foodstuff of various nutrient substances during

porcelain

manufacture to increase the dietary value of the

food, e.g., addition to wheat flour of vitamins B

niacin, and iron. In this way, the food is brought up

“Enhance” [Evans Vanodine]. TM for an

to a specific nutritional standard. (2) Increase in the

ultra high solid floor polish.

abundance of certain isotopes of an element by any

of several methods: (a) By a chemical reaction ac-

enhanced oil recovery. Any of several meth-

companied by irradiation from a laser beam; enrich-

ods for increasing the productivity of oil wells (after

ment of boron, chlorine, and sulfur isotopes has been

pumping is no longer effective) by emulsifying as

achieved in this way in a number of research labora-

much as possible of the oil trapped in the rock struc-

tories. Uranium enrichment is also possible, either

ture. Techniques that have been researched and used

by adding previously prepared

235

U to natural urani-

to some extent involve the pumping into the forma-

um or by the laser technique. (b) Uranium can also

tions of pressurized carbon dioxide, water, steam,

be enriched by gas centrifugation and gaseous diffu-

detergent solutions, brine, and a mixture of various

sion. The latter is the usual procedure. (3) Addition

high polymers, guar gum, xanthan biopolymer,

of oxygen to air to increase its combustion-support-

bauxite, or sand. Considerable success has been

ing ability.

achieved, but such methods have proved to be both

slow and inefficient.

enrobe. To coat candy centers, fruits, nuts, etc.,

See chemical flooding; hydraulic fracturing.

with a liquid confection such as chocolate or sugar

solution by mechanical dipping.

enhancer. (1) A food additive that brings out the

taste of a food product without contributing any taste

ensilage. A feed for livestock prepared by long

of its own. Sodium glutamate is the most widely

storage of corn husks, stalks, etc., in an air-tight

used substance of this class; its effective concentra-

vertical cylindrical structure (silo) in which the ma-

tion is in parts per thousand.

terial undergoes anaerobic fermentation. It is a com-

(2) a nucleotide sequence to which transcription

ponent of biomass.

factor(s) bind, and which increases the transcription

of a gene. It is NOT part of a promoter; the basic

enterokinase. An enzyme found in the small

difference being that an enhancer can be moved

intestine which converts trypsinogen into trypsin.

around anywhere in the general vicinity of the gene

(within several thousand nucleotides on either side

enterotoxin b, staphylococcal.

or even within an intron), and it will still function. It

CAS: 11100-45-1.

can even be clipped out and spliced back in back-

Hazard: A poison.

wards, and will still operate. A promoter, on the

Source: Natural product.

other hand, is position- and orientation-dependent.

Some enhancers are “conditional” in that they en-

enthalpy. The increase in heat content of a sub-

hance transcription only under certain conditions.

stance or system that accompanies its change from

See potentiator.

one state to another under constant pressure. The

internal energy plus the product of the volume and

enocianina. See grape skin extract.

pressure of a working substance.

enol. A chemical grouping containing both a dou- entrainer. An additive for liquid mixtures diffi-

ble bond (ene) and a hydroxyl group (OH), forming cult to separate by ordinary distillation. The entrain-

an intermediate and reversible product. Enols are er usually forms an azeotrope with one of the com-

characteristic of racemic compounds. pounds of the mixture and thereby aids in the

504ENTRAINMENT

separation of such a compound from the remainder lar weight from 10,000 to a million or more. An

important characteristic of enzymes is their specific-

of the mixture.

ity, i.e., a given enzyme can catalyze one particular

reaction and no others. Six types are recognized,

entrainment. The presence of minute drops of

which catalyze the following reactions: (1) redox

water or other liquid in the vapor produced by evap-

(oxidoreductases), (2) transfer of specific radicals or

oration or distillation; also small bubbles of air or

groups (transferases), (3) hydrolysis (proteolytic),

other gas in a liquid as a result of turbulence induced

(4) removal from or addition to the substrate of

by agitation. Entrained water or gas is often undesir-

specific chemical groups (lyases), (5) isomerizaton

able, and care needs to be taken to eliminate or

(isomerases), (6) combination or binding together of

prevent it; in certain cases it is beneficial.

substrate units (ligases). The names of enzymes in-

See venturi; entrainer.

variably terminate in either -ase or -in. The follow-

ing partial list indicates some of the more important

entropy (S). Thermodynamic concept referring

functions performed by enzymes; among these are

to heat content. If, during a reversible change at

the ability to cleave the peptide bonds of proteins

temperature T, an ammount dQ of heat enters the

(hydrolysis) with simultaneous formation of water;

substance, its entropy is augmented by:

and to decompose sugars and starches to ethyl alco-

hol and carbon dioxide (fermentation). Enzymes are

essential to many biochemical processes, especially

in the food, beverage, and pharmaceutical indus-

tries.

environmental chemistry. That aspect of

chemistry concerned with air and water pollution,

amylase starch hydrolysis

pesticides, and chemical and radioactive waste dis-

carboxylase decomposes pyruvic acid

posal. A random selection of specific areas of re-

cellulase converts cellulose to glu-

search includes lead and other toxic chemicals in the

cose

air, effects of increased burning of coal, biological

cholinesterase inactivates acetylcholine

modification of wastes, detoxification methods,

chymotrypsin hydrolysis of proteins

pesticide content of fish, environmental analytical

invertase converts sucrose to glucose

and monitoring techniques, utilization of biomass,

and fructose

drinking water quality, organic contaminants in

lipase hydrolysis of fats

lakes and rivers, and effect of deforestation on car-

maltase converts maltose to glucose

bon dioxide and oxygen content of air.

pepsin hydrolysis of proteins

protease hydrolysis of peptide

Environmental Protection Agency. (EPA).

linkages

A federal agency established in 1970. Under the

rennin hydrolysis of proteins

Toxic Substances Control Act of 1976, it is required

ribonuclease decomposes RNA

to ensure the safe manufacture, use, and transporta-

trypsin splits proteins to amino

tion of hazardous chemicals. It includes an Office of

acids

Hazardous Materials Control which administers

urease decomposes urea to NH

Congressional legislation pertaining to this field.

and CO

The EPA may require manufacturers to conduct

zymase converts sugars to alcohol

tests on materials or products that adversely affect

and CO

(fermentation)

the environment or public health and safety. One of

Recent research in biomimetic chemistry has suc-

the most important aspects of its activities is the

ceeded in creating synthetic enzymes that imitate the

establishment and supervision of automotive emis-

behavior of natural enzymes, e.g., chymotrypsin,

sion standards. It is also concerned with pesticides,

and are almost as effective. See catalyst; biomi-

fungicides, and other potentially detrimental materi-

metic chemistry; fermentation; hydrolysis.

als, as well as industrial waste disposal. It operates in

close conjunction with the U.S. Department of Agri-

culture and the Food and Drug Administration. The

eolotropic. See aeolotropic.

construction of new plants for manufacturing prod-

ucts must conform to EPA standards, especially as

regards effluents that contribute to water pollution.

eosin. (bromeosin; CI 45380; tetrabromofluor-

The headquarters are located at 1200 Pennsylvania

escein).

Avenue, N.W., Washington, DC 20460 Website:

CAS: 15086-94-9. C

http://www.epa.gov.

Properties: Red, crystalline powder. Soluble in alco-

See toxic substances; environmental chemistry.

hol and acetic acid; insoluble in water. The potassi-

um and sodium salts are soluble in water.

enzyme. Any of a unique class of proteins that Derivation: Bromination of fluorescein.

catalyze a broad spectrum of biochemical reactions. Use: Dyeing silk, cotton, and wool; red writing ink;

Enzymes are formed in living cells; they are com- cosmetic products; biological stain; coloring motor

prised one or more polypeptide chains with molecu- fuel.

505 EPINEPHRINE

EP. (1) Abbreviation for extreme pressure as ap- flash p 93F (33.9C) (TOC). Miscible with most

plied to lubricants. (2) Abbreviation for ethylene- organic solvents; slightly soluble in water.

Derivation: By removing hydrogen chloride from

propylene.

dichlorohydrin.

Hazard: Toxic by inhalation, ingestion, and skin

EPA. Abbreviation for Environmental Protection

absorption; strong irritant, a carcinogen. Flamma-

Agency.

ble, moderate fire risk. TLV: 0.5 ppm; animal car-

cinogen.

“EPAL” [Albemarle]. TM for linear primary

Use: Major raw material for epoxy and phenoxy

alcohols.

resins, manufacture of glycerol, curing propylene-

based rubbers, solvent for cellulose esters and

EPC black. Abbreviation for easy-processing

ethers, high-wet-strength resins for paper industry.

channel black.

See carbon black.

epichlorohydrin-bis(3-

aminopropyl)methylamine copolymer.

EPDM. Abbreviation for a terpolymer elastomer

CAS: 41941-50-8. mf: (C

•C

ClO)

made from ethylene-propylene diene monomer.

Hazard: Low toxicity by ingestion.

See ethylene-propylene terpolymer.

epichlorohydrin-dimethylamine copolymer.

ephedrine.