No. 1, Volume 2 
January 1998

  Dr. Claff
A chemist-turned-translator, Dr. Claff earned his B.S. and Ph.D. degrees in Organic Chemistry at M.I.T. in 1950 and 1953. His academic and industrial research experience included the fields of organosodium chemistry, synthetic rubber, leather tanning and finishing, acrylic and vinyl polymerization, adhesives for coated abrasives, and flexographic printing inks. His career later evolved into corporate administration and management in metalworking, heart-lung machines, biological instrumentation, printing, personnel administration, and paper box manufacturing. His exposure to such diverse disciplines has been a valuable resource in his career as a freelance technical translator since 1974.
   Dr. Claff and his wife Eleanor make their home in Brockton, Massachusetts, with their Maine coon cats, DownE and Baxter.
  Dr. Claff can be reached at

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A Translator’s Guide to Organic Chemical Nomenclature X
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A Translator’s Guide to Organic Chemical Nomenclature

Part X

by Chester E. Claff, Jr., Ph. D.
Download the zipped version of the first installments of this series, originally published in the Sci-Tech Translation Journal, of the American Translators Association. The file is approximately 87 KB.

Part IX of this series appeared in the October, 1997.issue of the Translation Journal.

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V. Organic Oxygen Compounds (continued)

Carboxylic Acids

In Part IX of this series we saw that compounds with two hydroxyl groups bonded to a terminal carbon atom split off a molecule of water spontaneously to form aldehydes. A similar process occurs when a terminal carbon atom carries three hydroxyl groups, giving rise to carboxylic acids as follows:


The carboxylic acids are usually written as RCO2H, RC(O)OH, or RC(=O)OH, where R can stand for any organic group. When R is an aliphatic group, the acids are called fatty acids. Depending on whether or not the group R contains one or more double bonds, the fatty acids can be saturated or unsaturated (referred to popularly as monounsaturated or polyunsaturated fatty acids).

Some of the more common fatty acids are described below in Table 11.

Table 11. Representative Fatty Acids
R Trivial
Systematic Name


Formic acid

Methanoic acid


Acetic acid

Ethanoic acid


Propionic acid

Propanoic acid


Butyric acid

Butanoic acid


Valeric acid

Pentanoic acid


Caproic acid

Hexanoic acid


Enanthic acid

Heptanoic acid


Caprylic acid

Octanoic acid


Pelargonic acid

Nonanoic acid


Capric acid

Decanoic acid


Lauric acid

Dodecanoic acid


Myristic acid

Tetradecanoic acid


Palmitic acid

Hexadecanoic acid


Stearic acid

Octadecanoic acid


Oleic acid

cis-9-Octadecenoic acid

n-C5H11CH=CHCH2CH=CH(CH 2)7-

Linoleic acid

cis,cis-9,12-Octadecadienoic acid

  Some possible sources of confusion exist between caproic acid and capric acid, and between linoleic acid and linolenic acid (9,12,15-octadecatrienoic acid, which has three double bonds).
   Halogenated fatty acids are also common. Some examples are:
  chloroacetic acid ClCH2CO2H,
  trichloroacetic acid Cl3CCO2H,
  a-chloropropionic acid (2-chloropropanoic acid) CH3CHClCO2H,
  b-bromopropionic acid (3-bromopropanoic acid) BrCH2CH2CO2H,
  g-iodobutyric acid (4-iodobutanoic acid) ICH2CH2CH2CO2H.

Note that locants can be of either type. The a-position, on the carbon adjacent to the carboxyl group, is the same as the 2-position.
  In German, Carbonsäure nearly always means carboxylic acid, not carbonic acid which is properly Kohlensäure. In compounds, -carbonsäure always means carboxylic acid and -säure means acid. Thus Essigsäure is acetic acid and Propionsäure is propionic acid. In the case of acetic acid, there are two German terms that require some explanation. Pure acetic acid freezes (and conversely melts) at just below room temperature (62°F, 16.7°C), and may thus be solid or liquid depending on laboratory conditions. Since it freezes so readily, pure acetic acid is called glacial acetic acid in English and Eisessig in German. Small amounts of water liquefy the substance, in which case it is called simply acetic acid or Essigsäure. Vinegar, of course, is dilute acetic acid.
  Locants for cyclic ethers are also designated as a, b, or g, or 2, 3, or 4 with respect to the oxygen atom. Thus furan can give rise to a-furoic acid (2-furancarboxylic acid) or b-furoic acid (3-furancarboxylic acid). Names such as 2-tetrahydrofurancarboxylic acid (2-carboxytetrahydrofuran) or analogous names for its 3-isomer are also acceptable.

Dicarboxylic Acids

Dicarboxylic acids are common in nature and in the laboratory, and have been given their own trivial names. They are used with diols to produce polyesters and are also used to produce polyamides (Nylon). Some of the common ones are listed below in Table 12.

Table 12. Representative Dicarboxylic Acids

  Chemical Structure

Trivial (Common) Name


Oxalic acid


Malonic acid


Succinic acid


Maleic acid


Fumaric acid


Glutaric acid


Adipic acid


Pimelic acid


Suberic acid


Azelaic acid


Sebacic acid

A simple mnemonic for remembering the names of the saturated aliphatic a,w-dicarboxylic acids is “Oh My, Such Good Apple Pie, Sweet As Sugar!” (This does not include the unsaturated maleic and fumaric acids).

Hydroxy Acids

Some of the simple hydroxy acids have also been given trivial names:

Table 13. Representative Hydroxy Acids


Carbonic acid


Glycolic acid


Lactic acid


Malic acid


Tartaric acid


Citric acid

Keto Acids

Some examples with trivial names are:


Pyruvic acid


Levulinic acid
HO2CCH2C(=O)CH2CO2H Acetonedicarboxylic acid
CH3C(=O)CH2CO2H Acetoacetic acid


Unsaturated Acids

In addition to maleic and fumaric acids (Table 12), some important unsaturated acids are:


Acrylic acid


Methacrylic acid


Crotonic acid


Itaconic acid


Citraconic acid


Aconitic acid


Propiolic acid

Acrylic and methacrylic acids are widely used in polymerization to prepare polyacrylic resins.

IN THE NEWS - Review your comprehension of Parts I to X:

The November 24, 1997, issue of Chemical & Engineering News reports:

“BP Chemicals to build butanediol plant...

BP Chemicals ... will build a $100 million, 140-million-lb-per-year 1,4-butanediol plant ... Geminox uses a direct dual-reactor route to produce 1,4-butanediol and its derivatives using butane instead of acetylene, butadiene, or propylene oxide, as do other technologies ... 1,4-Butanediol is used to make tetrahydrofuran, which is used to make fibers and solvents...”

We have discussed all of the organic chemicals mentioned in the extract above. Can you draw their structures and roughly understand how the processes might work? If so, you are on the way to being “chemistry-literate!” The terminology you have learned not only is of theoretical interest, but will help you to understand and appreciate practical industrial matters of current significance.
  Part XI will describe derivatives of carboxylic acids including esters, anhydrides, lactones, and salts.

Readers are urged to e-mail questions, comments, or suggestions for further topics in the field of organic nomenclature to the author at:

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Updated 12/24/97