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 :

acid 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

[1] Organic chemists will note that some degree of generality and rigor has been sacrificed here for the sake of clarity. Terminology sometimes differed in the nineteenth century; such distinctions are explained in the text.

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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

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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

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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

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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

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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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