1 17.4 Esters of Carboxylic Acids 17.5 Naming Esters 17.6 Properties of Esters Chapter 17 Carboxylic Acids And Esters.

1

17.4 Esters of Carboxylic Acids

17.5 Naming Esters

17.6 Properties of Esters

Chapter 17 Carboxylic Acids And Esters

2

In an ester, the H in the carboxyl group is replaced by an alkyl group.

O CH3—C—O—CH3

CH3—COO—CH3

ester group

Esters

3

An ester is produced by the reaction of a carboxylic acid and alcohol in the presence of an acid catalyst.

O H+

CH3—C—OH + HO—CH2—CH3

O

CH3—C—O—CH2—CH3 + H2O

Esterification

4

Ester Products

Aspirin: Is used to relieve pain and

reduce inflammation. Is an ester of salicylic acid

and acetic acid.Oil of wintergreen: Is used to soothe sore

muscles. Is an ester of salicylic acid

and methanol.

C

O

OH

O C

O

CH3

Acetylsalicylic acid(Aspirin)

C

O

O CH3

OH

Methyl salicylate(Oil of wintergreen)

5

Esters are named with the alkyl name of the alcohol followed by the carboxylate name from the acid.

from acid from alcohol O

methylCH3—C—O—CH3

Ethanoate methyl ethanoate (IUPAC) (Acetate) methyl acetate (common)

Naming Esters

6

Esters give fruits their pleasant fragrances and flavors.

Some Esters In Nature

7

In hydrolysis: An ester reacts with water to produce a carboxylic

acid and an alcohol. An acid catalyst is required.

O H+

H—C—O—CH2—CH3 + H2O

O

H—C—OH + HO—CH2—CH3

Hydrolysis

8

In base hydrolysis or saponification, an ester reacts with a strong base to produce the salt of the carboxylic acid and an alcohol. O

|| CH3—C—O—CH2—CH3 + NaOH

O CH3—C—O– Na+ + HO—CH2—CH3

salt of carboxylic acid alcohol

Base Hydrolysis (Saponification)

9

Base Hydrolysis of Fatty Acids Produces Soaps

10

Cleaning Action of Soap

A soap: Contains a nonpolar carbon

end that dissolves in nonpolar fats and oils, and a polar end that dissolves in water.

Forms groups of soap molecules called micelles that dissolve in water and are washed away.