No. 2, Volume 1 
October 1997

  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

 Jul 97 Issue
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Dictator v. Dictator
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Science & Technology
A Translator’s Guide to Organic Chemical Nomenclature IX
by Chester E. Claff, Jr., Ph.D.
Banking and Finance
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Translation Journal

A Translator’s Guide to Organic Chemical Nomenclature

Part IX

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.


V. Organic Oxygen Compounds (continued)

Structural Diagrams

It becomes burdensome and cluttered to represent each atom in complex molecules by atomic symbols C, H, O, etc., accompanied by multiplying subscripts. A convenient shorthand representation has evolved that is unequivocal, precise, and easily comprehended. In these structural diagrams, all of the carbon-to-carbon bonds of a compound are shown as straight line segments, either single, double, or triple. Carbon atoms are implied at all intersections of line segments, at their ends, and at all vertices. Hydrogen atoms bonded to carbon atoms are not shown, nor are carbon-to-hydrogen bonds; they are implied in such number that the carbon valence of four is filled. All other hydrogen atoms (e.g. in hydroxyl groups) are shown as H, and substituents on cyclic compounds are usually, but not necessarily, shown in full.


Thus CH3CH2CH2CH3 becomes simply and
CH3CCCH3 becomes .


Atoms other than carbon and hydrogen are always represented by their symbols. Examples are as follows:
=trans-2-Butene =
=Ethylene oxide=

More Cyclic Ethers

Returning now to our main stream of thought, further representative examples of cyclic ethers are shown below:

Propylene oxide   Glycidol
Furan   Tetrahydrofuran (THF)
Pyran   Tetrahydropyran
 Dioxane   1,4-Dioxin
   2,3,7,8-Tetrachlorodibenzodioxin (TCDD). This is the “dioxin” of pollution infamy.


Ketones and Aldehydes

Compounds with two hydroxyl groups bonded to a single carbon atom are unstable in general. They split off a molecule of water spontaneously to form ketones or aldehydes with an oxygen atom double-bonded to carbon:
The product is a ketone, often written RCOR'.
The product is an aldehyde, often written RCHO.


Some common aldehydes are:
HCHOFormaldehyde; methanal
CH3CHOAcetaldehyde; ethanal
OHCCHOGlyoxal; ethanedial
CH3CH2CHOPropionaldehyde; propanal
CH2=CHCHOAcrolein; propenal
CH3(CH2)2CHOButyraldehyde; butanal
CH3(CH2)3CHOValeraldehyde; pentanal
(CH3)2CHCH2CHO Isovaleraldehyde; 3-methylbutanal
CH3(CH2)4CHO Caproaldehyde; hexanal

Some representative ketones are:
CH3COCH3Acetone; 2-propanone; 2-oxopropane; 2-ketopropane; dimethyl ketone
CH3COCH2CH3Methyl ethyl ketone (MEK); 2-butanone; 2-oxobutane; 2-ketobutane
CH3COCH=CH2Methyl vinyl ketone; 3-butenone
CH3COCH2COCH3 2,4-Pentanedione
Camphor; 2-camphanone


Review of Systematic Name Endings and Prefixes

The classes of compounds considered so far have the following systematic name endings:
-ane=Saturated aliphatic hydrocarbon
-ene=Aliphatic hydrocarbon containing a double bond
-yne=Aliphatic hydrocarbon containing a triple bond
-enyne=Aliphatic hydrocarbon containing both a double and a triple bond
-yl=Radical or group
-ylidene=Group disubstituted on a terminal carbon atom

Some of the systematic name prefixes we have mentioned are:
halo-=(Chloro-, bromo-, etc.) halogen-substituted
oxo- or keto- =Containing an oxygen atom double-bonded to a carbon atom that in turn is bonded to two other carbon atoms

By now it must be abundantly clear that optional names exist for most organic compounds.

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

 © Copyright 1997 Gabe Bokor
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Updated 09/22/97