Organic Chemistry

734 CHAPTER 18 Carbonyl Compounds II

If the compound has both an alkene and an aldehyde functional group, the alkene is

cited first, with the “e”ending omitted to avoid two successive vowels (Section 8.1).

Ketones

The systematic name of a ketone is obtained by removing the “e”from the name of the

parent hydrocarbon and adding “one.”The chain is numbered in the direction that

gives the carbonyl carbon the smaller number. In the case of cyclic ketones, a number

is not necessary because the carbonyl carbon is assumed to be at the 1-position.

Frequently, derived names are used for ketones—the substituents attached to the

carbonyl group are cited in alphabetical order, followed by “ketone.”

Only a few ketones have common names. The smallest ketone, propanone, is usual-

ly referred to by its common name, acetone. Acetone is a common laboratory solvent.

Common names are also used for some phenyl-substituted ketones; the number of car-

bons (other than those of the phenyl group) is indicated by the common name of the

corresponding carboxylic acid, substituting “ophenone”for “ic acid.”

If the ketone has a second functional group of higher naming priority, the ketone

oxygen is indicated by the prefix “oxo.”

O

O O

O

systematic name: 4-oxopentanal methyl 3-oxobutanoate 2-(3-oxopentyl)-

cyclohexanone

O OCH 3

O

H

3-pentenal

CH 3 CH CHCH 2 H

C

O

propanone

acetone

dimethyl ketone

systematic name:

common name:

derived name:

3-hexanone

ethyl propyl ketone

6-methyl-2-heptanone

isohexyl methyl ketone

CH 3 CH 3

C

O

CH 3 CH 2 CH 2 CH 2 CH 3

C

O

CH 3 CHCH 2 CH 2 CH 2 CH 3

CH 3

C

O

CH 3 C

CH 3

O

CH 3 CH 2 CH 3 CH 3 CH CHCH 2

systematic name: cyclohexanone butanedione

common name:

2,4-pentanedione

acetylacetone

4-hexen-2-one

C

O

O

C

O

CH 3

C

O

C

O

CH 3

acetophenone

methyl phenyl ketone

butyrophenone

phenyl propyl ketone

benzophenone

diphenyl ketone

common name:

derived name:

C

O

CH 2 CH 2 CH 3

C

O

C

O

Tutorial:

Nomenclature of aldehydes

and ketones