The Foundations of Chemistry

27-14 Some Derivatives of Carboxylic Acids 1081

Naturally occurring fats and oils are mixtures of many different esters. Milk fat, lard,
and tallow are familiar, important fats. Soybean oil, cottonseed oil, linseed oil, palm oil,
and coconut oil are examples of important oils.
The triesters of glycerol are called glycerides. Simple glyceridesare esters in which all
three R groups are identical. Two examples are

Waxesare esters of fatty acids and alcohols other than glycerol. Most are derived from
long-chain fatty acids and long-chain monohydric alcohols. Both usually contain even
numbers of carbon atoms. Beeswax is largely C 15 H 31 COOC 30 H 61 ; carnauba wax contains
C 25 H 51 COOC 30 H 61. Both are esters of myricyl alcohol, C 30 H 61 OH.
Fats are solid esters of glycerol and (mostly) saturated acids. Oils are liquid esters that
are derived primarily from unsaturated acids and glycerol. The acid portion of a fat usually
contains an even number of carbon atoms, often 16 or 18. Some acids that occur frequently
in fats and oils are

butyric CH 3 CH 2 CH 2 COOH

lauric CH 3 (CH 2 ) 10 COOH

myristic CH 3 (CH 2 ) 12 COOH

palmitic CH 3 (CH 2 ) 14 COOH

stearic CH 3 (CH 2 ) 16 COOH

oleic CH 3 (CH 2 ) 7 CHUCH(CH 2 ) 7 COOH

linolenic CH 3 CH 2 CHUCHCH 2 CHUCHCH 2 CHUCH(CH 2 ) 7 COOH

ricinoleic CH 3 (CH 2 ) 5 CHOHCH 2 CHUCH(CH 2 ) 7 COOH

Figure 27-19a shows a model of stearic acid, a long-chain saturated fatty acid.

Amides

Amidesare thought of as derivatives of organic acids and ammonia, primary amines, or

secondary amines. Amides contain the C N functional group. They are named as

O

H 2 C (CH 2 ) 14 CH 3

(CH 2 ) 14 CH 3

(CH 2 ) 14 CH 3

O C

O

O

O

HC C

O

H 2 C C

O

H 2 C (CH 2 ) 16 CH 3

(CH 2 ) 16 CH 3

(CH 2 ) 16 CH 3

O C

O

O

O

HC C

O

H 2 C C

O

glyceryl tristearate

(stearin)

glyceryl tripalmitate

(palmitin)

ROC CH 2

O

O

O

R C CH

O

R C CH 2

O

C

O

The fatty acid portions,R , may be saturated or unsaturated.

The R’s may be in the same or different groups.

Most natural fatty acids contain even

numbers of carbon atoms because they

are synthesized in the body from two-

carbon acetyl groups.

Honeybees produce the wax to build

their honeycombs.

Glycerol is

CH 2

HO CH

HO

HO

CH 2