Organic Chemistry

674 CHAPTER 17 Carbonyl Compounds I

Esters

An esteris a compound that has an group in place of the OH group of a carboxylic

acid. In naming an ester, the name of the group attached to the carboxyl oxygenis

stated first, followed by the name of the acid, with “ic acid”replaced by “ate.”

Salts of carboxylic acids are named in the same way. The cation is named first, followed

by the name of the acid, again with “ic acid”replaced by “ate.”

Cyclic esters are called lactones. In systematic nomenclature, they are named as

“2-oxacycloalkanones.”Their common names are derived from the common name of the

carboxylic acid, which designates the length of the carbon chain, and a Greek letter to

indicate the carbon to which the carboxyl oxygen is attached. Thus, four-membered ring

lactones are (the carboxyl oxygen is on the ), five-membered

ring lactones are and six-membered ring lactones are

PROBLEM 1

The word “lactone”has its origin in lactic acid, a three-carbon carboxylic acid with an OH

group on the a-carbon.Ironically, lactic acid cannot form a lactone. Why not?

g-lactones, d-lactones.

b-lactones b-carbon

(R¿)

OR¿

ethanoic anhydride

acetic anhydride

a symmetrical anhydride

ethanoic methanoic anhydride

acetic formic anhydride

a mixed anhydride

systematic name:

common name:

CH 3 O CH 3

C

O

C

O

CH 3 O H

C

O

C

O

Tutorial:

Nomenclature of carboxylic

acids and their derivatives

3-D Molecules:

-Caprolactone;

cis-2-Ethylcyclohexane-

carboxamide

d

CH 3

O

O

O

O

CH 2 CH 3

O O

OO

2-oxacyclopentanone

-butyrolactone

2-oxacyclohexanone

-valerolactone

3-methyl-2-oxacyclohexanone

-caprolactone

3-ethyl-2-oxacyclopentanone

-caprolactone

sodium methanoate

sodium formate

potassium ethanoate

potassium acetate

sodium benzenecarboxylate

sodium benzoate

systematic name:

common name:

H O−^ Na+

C

O

CH 3 O−^ K+

C

O

O− Na+

C

O

carbonyl oxygen

carboxyl oxygen

ethyl ethanoate

ethyl acetate

phenyl propanoate

phenyl propionate

methyl 3-bromobutanoate

methyl -bromobutyrate

systematic name: ethyl cyclohexanecarboxylate

common name:

R OR′

C

O

CH 3 OCH 2 CH 3

C

O

CH 3 CHCH 2 OCH 3

C

O

Br

OCH 2 CH 3

C

O

CH 3 CH 2 O

C

O