Page 282 - Theory and Problems of BEGINNING CHEMISTRY

CHAP. 18] ORGANIC CHEMISTRY 271

18.9. ALDEHYDES AND KETONES
Aldehydes are produced by the mild oxidation of primary alcohols—alcohols with the —OH group on an
end carbon atom.
O
CH 3 CH 2 OH CH 3 CH
mild oxidation
ethanol or ethyl alcohol ethanal or acetaldehyde
The mild oxidation of a secondary alcohol (with the —OH group on a carbon atom connected to two other carbon
atoms) produces a ketone.
CH 3 CH CH 3 CH 3 C CH 3
oxidation
OH O
2-propanol or isopropyl alcohol propanone or acetone

Each of these groups is characterized by having a carbonyl group, C O, but the aldehyde has the C O
group on one end of the carbon chain, and the ketone has the C O group on a carbon other than one on the
end. Acetone is a familar solvent for varnishes and lacquers. As such, it is used as a nail polish remover. The
systematic name ending for aldehydes is -al; that for ketones is -one.

18.10. ACIDS AND ESTERS
Acids can be produced by the oxidation of aldehydes or primary alcohols. For example, the souring of wine
results from the oxidation of the ethyl alcohol in wine to acetic acid:
CH CH OH CH 3 C O H
3
2
oxidation
ethanol
O
ethanoic acid or acetic acid
A solution of acetic acid formed in this manner is familar as vinegar. The name ending for organic acids is −oic
acid, so the systematic name for acetic acid is ethanoic acid.
Acids react with alcohols to produce esters:
CH CO H + HOCH CH 3 CH CO CH CH + H O
2
3
2
2
3
2
2
3
acetic acid ethyl alcohol ethyl acetate water
(an ester)
Many simple esters have a pleasant, fruity odor. Indeed, the odors of many fruits and oils are due to esters. Esters
are named by combining the radical name of the alcohol with that of the negative ion of the acid. The ending
-ate replaces the -oic acid of the parent acid. The ester in the equation above is an example.
EXAMPLE 18.5. Name the following esters:
(a) C H OCCH 3 and (b) C H OCH
9
4
5
6
O O
Ans. (a) Butyl acetate or butyl ethanoate (b) Phenyl formate or phenyl methanoate
The formation of an ester from an alcohol and an acid is an equilibrium reaction. The reverse reaction can
be promoted by removing the acid from the reaction mixture, for example, by treating it with NaOH. Animal