Alkyl Group Symbols

by Axel Drefahl • www.axeleratio.com
Alkyl group symbols are often found in the chemical literature to keep names and formulae of chemical compounds at a reasonable size. The Chemical Property Viewer accepts alkyl group symbols to shorten query strings and to reduce or eliminate the need for integer subscripts.
Handbook for Estimating Physicochemical Properties of Organic Compounds
by Martin Reinhard and Axel Drefahl
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The following table lists symbols for n-alkyl groups valid within search queries in the Chemical Property Viewer.
Formula Symbol Group Name
—CH3 Me methyl
—CH2CH3 Et ethyl
—(CH2)2CH3 Pr propyl
—(CH2)3CH3 Bu butyl
—(CH2)4CH3 Pe pentyl
—(CH2)5CH3 Hx hexyl
—(CH2)6CH3 Hp heptyl
—(CH2)7CH3 Oc octyl
—(CH2)8CH3 Nn nonyl
—(CH2)9CH3 De decyl
—(CH2)10CH3 Un undecyl
—(CH2)11CH3 Do dodecyl
—(CH2)19CH3 Cn cosanyl

Applications and examples of usage
Short Notations for Organic Cations
Short Notations for Organic Anions

Since alkyl group symbols have the same appearance as many element symbols — one upper-case letter followed by one lower-case letter — it is desirable that alkyl group symbols do not coincide with element symbols. We choose Nn for nonyl instead of No, since the latter symbol stands for the chemical element nobelium. The symbol for the n-propyl group is Pr, which also denotes the chemical element praseodymium. Pr is so frequently used to symbolize the propyl group that it would seem awkward to define a different notation. Therefore, we stick to the so-often-applied hope that context overwrites ambiguity.
In some instances, the following three-letter symbols may be used to denote branched alkyl groups: iPr for iso-propyl, iBu for iso-butyl, sBu for sec-butyl and tBu for tert-butyl.
Three-letter symbols are also used for the linear alkyl chains with 13 to 19 C-atoms:
Formula Symbol Group Name
—(CH2)12CH3 trD tridecyl
—(CH2)13CH3 teD tetradecyl
—(CH2)14CH3 peD pentadecyl
—(CH2)15CH3 hxD hexadecyl
—(CH2)16CH3 hpD heptadecyl
—(CH2)17CH3 ocD octadecyl
—(CH2)18CH3 nnD nonadecyl
Three-letter symbols, if used in structural notations, are placed inside square brackets. For example, [hxD]OH is a valid formula for n-hexadecanol. And 1R3[iBu]IM represents the class of 1-alkyl-3-isobutylimidazolium cations.
Last update was made on October 24 in 2008 by Axel Drefahl
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