Preamble

Elision of Vowels

The terminal "e" in names of parent compounds is elided when followed by a suffix beginning with "a", "I", or "o":

Examples:	Cf. Rule
4-Penten(e)-1-ol	C-10.3
2-Hexan(e)amine	C-11.42
Anilin(e)ium	C-82.2
Butan(e)ide	C-84.3
1-Chrysen(e)ol	C-202.1
Hexan(e)al	C-302.1
2-Butan(e)one	C-312.1
Heptan(e)oic acid	C-401.1
5-Pentan(e)olide	C-472.2
1-Hexan(e)imine	C-815.3
Hexan(e)amide	C-822.1

The terminal "a" in the names of multiplying affixes is elided when followed by a suffix or ending (not a separate word) beginning with "a" or "o":

Examples:	Cf. Rule
[1,1'-Binaphthalene]-3,3',4,4'-tetramine	C-71.3
1,3,6,8(2H,7H)-Pyrenetetrone	C-315.1
Benzenehexol

There is no elision in the following cases:

(1) in conjunctive nomenclature,	Cf. Rule
e.g., Quinolineacetic acid	C-51.2
,-Dimethyl-2-naphthaleneethanol	C-52.1
(2) in replacement nomenclature,
e.g., Tetraoxatridecane	C-61.1
(3) in multiplying parent compounds,
e.g., Ethylenediaminetetraacetic acid	C-815.1
(4) with multiplying prefixes,
e.g., 1,4,6,9-Tetraoxo-2-pyrenecarboxylic acid

(5) The terminal "e" in the names of parent hydrides is elided when adding "-yl" in formation of names of radicals. For example, pyrene, pyrenyl. However, when ambiguity results the "e" is retained, e.g. pentaphene, pentapheneyl to avoid confusion with pentaphenyl (five phenyl radicals).

(6) For elision of vowels in forming names of fused polycyclic compounds see Rule A-21.4 and in Hantzsch-Widman names see Rule B-1.1.

See Recommendations'93 R-0.1.7