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B. Modern Chemical Definitions[1]

acetic acid = essence of vinegar: CH3 CO2 H

acetoacetic ester: CH3 COCH2 CO2 CH2 CH3 , produced by self-condensation of ethyl acetate, CH3 CO2 CH2 CH3

acetone: CH3 COCH3 , the simplest ketone

acetyl: CH3 CO- (the oxygen is double bonded to carbon, which has an untilled valence)

acetylene :  imageacid anhydride: acid from which the elements of water (H2 O) have been extracted

acid chloride: compound of the form RCOCl

alanine: CH3 CH(NH2 )CO2 H, aminopropionic acid

alcohol: loosely, a compound with a hydroxyl (-OH) group

aldehyde: any compound whose carbon chain ends in -CH=O

aldehyde (loosely) = acetaldehyde: CH3 CHO

aliphatic compound: non-benzenoid organic compound


alkyl: saturated hydrocarbon radical, often symbolized generically as "R"

amide: compound of the form RCONH2 (this particular example is a primary amide)

amine: compound of the form NR3 , where the R's are hydrogen or hydrocarbon groups

amino acid: compound with both amine and carboxylic acid groups

amyl: a five-carbon saturated hydrocarbon radical

amylene: a five-carbon olefin

aniline: C6 H5 NH2 , aminobenzene

anthranilic acid:ortho -aminobenzoic acid

aromatic compound: organic compound derived from benzene

-ate: suffix indicating ester or salt of an acid

benzaldehyde: C6 H5 CHO, benzoyl hydride

benzene: C6 H6

benzoic acid: C6 H5 CO2 H, benzenecarboxylic acid

benzonitrile: C6 H5 CN

benzoyl: C6 H5 CO-, phenyl carbonyl

benzyl alcohol: C6 H5 CH2 OH

butane: a four-carbon saturated hydrocarbon

butyl: a four-carbon saturated hydrocarbon radical

butylene: a four-carbon olefin

butyric acid: a four-carbon carboxylic acid

caproic acid: a six-carbon carboxylic acid

carbohydrate: a compound exhibiting a multiple of the formula CH2 O

carbonyl: functional group consisting of a carbon atom double bonded to oxygen

carboxyl: -COOH, confers acid character on a molecule

carboxylic acid: loosely, an organic acid, or a compound with a carboxyl group

chloroform: CHCl3

condensation: amalgamation of two molecules into one, often with loss of H2 O

cresol: methyl phenol, MeC6 H4 OH

cyanogen: NC-CN

cyclohexamethine: any proposed structure for benzene exhibiting a cyclical array of six trivalent CH groups


cyclohexatriene: Kekulé's hexagonal benzene formula, possessing three carbon-carbon double bonds and three carbon-carbon single bonds; an example of a cyclohexamethine theory

dibasic acid: acid having two replaceable hydrogen atoms; a double acid

dimer: compound formed of two identical parts, a "doubled" molecule

dithionic acid = hyposulfuric acid: H2 S2 O6

ester: compound of the form RCO2 R, resulting from condensation of an organic acid and an alcohol

ethane: CH3 CH3

ether: compound of the form R-O-R, where the R's are hydrocarbon radicals

ether (loosely) = diethyl ether: CH3 CH2 OCH2 CH3 or EtOEt

ethyl: CH3 CH2 -, often symbolized Et

ethyl alcohol = (loosely) alcohol: CH3 CH2 OH or EtOH

ethylamine: EtNH2

ethylene: CH2 =CH2 , the simplest olefin or alkene

ethylidene: CH3 CH= (a radical, or incomplete molecule)

fatty acid: large organic acids found as components of fats

formic acid: HCO2 H

functional group: any site on an organic molecule that has a multiple bond or a heteroatom

glyceride: ester of fatty acid(s) plus glycerin; triglycerides are fats

glycerin: CH2 OHCHOHCH2 OH, a trialcohol

glycine = glycocoll: aminoacetic acid

glycol: compound with two hydroxyl groups, a dialcohol

glycol (loosely) = ethylene glycol: CH2 OHCH2 OH

glycolic acid: CH2 OHCO2 H

glyoxal: OHCCHO

halide: chloride, bromide, iodide, or fluoride

halogen: chlorine, bromine, iodine, or fluorine


heteroatom: in an organic molecule, any atom other than hydrogen or carbon

homolog: a member of a homologous series

homologous series: series of organic compounds that differ only by successive CH2 (methylene) groups, each methylene representing a link in the carbon chain

hydracid: compound whose acidity is unconnected with its oxygen content

hydride: compound of the form X-H, where X may be almost any atom or radical

hydrocarbon: a compound consisting only of hydrogen and carbon

hydrolysis: reaction with water, often splitting the reactant molecule

hydroxyl: -OH, confers alcohol character

iso-: prefix indicating either (1) a new isomer of a familiar compound hitherto thought to have no isomers; or (2) a branched-chain hydrocarbon

isoamyl: Me2 CHCH2 CH2 -

isobutyl: Me2 CHCH2 -

isobutyric acid: Me2 CHCO2 H

isomers: compounds with the identical formula but different structures, that is, compounds that have the same sorts and numbers of atoms but arranged differently

isopropyl alcohol: CH3 CH(OH)CH3

ketone: compound of the form RCOR, that is, carbonyl flanked by two alkyl radicals

lactic acid: CH3 CH(OH)CO2 H

leucic acid: a six-carbon hydroxy acid

leucine: a six-carbon amino acid

malic acid: a four-carbon hydroxy diacid; hydroxysuccinic acid

malonic acid: HO2 CCH2 CO2 H, a three-carbon diacid

methane: CH4 , called "marsh gas" in the nineteenth century

methine: CH, a trivalent radical

methyl: CH3 -, often symbolized Me

methylamine: MeNH2


methylene: CH2 , a divalent radical

methylsulfonyl chloride: CH3 SO2 C1

methylsulfonic acid: CH3 SO3 H

moiety: organic-chemical term indicating a portion of a molecule

nitrile = cyanide: compound with the group -CN

normal: possessing a straight (unbranched) carbon chain, symbolized n -

octane: an eight-carbon saturated hydrocarbon

olefin: a hydrocarbon with a carbon-carbon double bond; alkene

ortho/meta/para: referring to aromatic isomers distinguished by virtue of two substituents occupying different positions on the benzene hexagon-on adjacent carbons (1,2), separated by one carbon (1,3), or on opposing carbons (1,4), respectively

oxalic acid: HO2 CCO2 H

oxyacid: compound whose acidity is related to its oxygen content

paraffin: a hydrocarbon with no multiple bonds; alkane

pentane: a five-carbon saturated hydrocarbon

phenol = carbolic acid: phenyl hydroxide or hydroxybenzene, C6 H5 OH

phenyl: C6 H5 -

phosgene = carbonyl chloride: COCl2

polymer: compound formed of many identical parts

primary alcohol or amine: compound of the form RCH2 OH or RNH2

propane: CH3 CH2 CH3

propionic acid: CH3 CH2 CO2 H

propyl =n-propyl = normal propyl: CH3 CH2 CH2 -

propylene: CH3 CH=CH2

salicylic acid:ortho -hydroxybenzoic acid

saturated: organic compound possessing no carbon-carbon multiple bonds

secondary alcohol or amine: compound of the form R2 CHOH or R2 NH

succinic acid: a four-carbon saturated dicarboxylic acid


sulfonic acid: a compound of the form RSO3 H

tartaric acid: a four-carbon dihydroxy diacid; dihydroxysuccinic acid

tertiary alcohol or amine: a compound of the form R3 COH or R3 N

tertiary butyl alcohol =t-butyl alcohol: Me3 COH

toluene: methylbenzene

unsaturated: possessing carbon-carbon multiple bonds (can absorb hydrogen gas)

valence: number of bonds a given kind of atom can form to other atoms

valeric acid: a five-carbon carboxylic acid


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