E
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
20
H
27
O
5
SNa.
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
51
H
64
N
12
O
12
S
2
.
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-
C
5
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
4.
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
2
CO
3
10H
2
O), which
loses almost all its water constituent spontaneously.
EDC (reagent).
CAS: 25952-53-8. mf: C
8
H
17
N
3
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
20
H
60
O
8
Si
9
.
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
20
H
42
. 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
3
[CH
2
]
7
HC:CH[CH
2
]
7
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
23
H
27
NOC
6
H
8
O
7
.
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-
Al
+3
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
2
O H
2
+Cl
2
+ 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).
Cu
+2
. 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
58
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
,7
,10,11-
tetramethoxyemetan).
resins). TM for polymer products.
CAS: 483-18-1. C
29
H
40
O
4
N
2
. 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
17
H
22
N
2
O
3
.
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
14
H
4
O
2
(OH)
3
CH
3
.
CAS: 87233-62-3. mf: C
17
H
26
N
4
O2C
4
H
4
O
4
.
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
28
H
41
N
3
O
3
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]
3
(NO
3
)
3
.
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
6
Cl
5
S)
2
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
3
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
9
H
8
O
3
).
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
6
H
6
Cl
6
O
3
S.
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
3
;
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
8
H
8
Na
2
O
5
.
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-
mc
2
(Einstein) or E
=
hn (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
3
O)
2
P(O)SCH
2
C
:CHC(O)C(OCH
3
):CH
O.
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
12
H
8
OCl
6
. 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
3
;
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
3
H
2
ClF
5
O.
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
23
H
28
O
6
.
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
1
,B
2
,
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-
dQ
hol and carbon dioxide (fermentation). Enzymes are
dS
=
T
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
4
Congressional legislation pertaining to this field.
and CO
2
.
The EPA may require manufacturers to conduct
zymase converts sugars to alcohol
tests on materials or products that adversely affect
and CO
2
(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
20
H
8
Br
4
O
5
.
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
7
H
19
N
3
C
3
H
5
ClO)
x
made from ethylene-propylene diene monomer.
Hazard: Low toxicity by ingestion.
See ethylene-propylene terpolymer.
epichlorohydrin-dimethylamine copolymer.
ephedrine.