Esters

Functional Group

Nomenclature

The carbon chain that came from the alcohol is given the suffix "-yl" as if it is a side chain.

The other carbon chain (containing the C=O bond) is given the suffix "-anoate". This is also the suffix for a salt made from a carboxylic acid.

Preparation

Esters can be made by reacting alcohols with either:

- carboxylic acids, with concentrated sulfuric acid and heat, OR

- acid chlorides

Reactions

HYDROLYSIS

Acidic and alkaline conditions can break the ester bond:

Acidic Conditions

Alkaline Conditions - note the different products!

SAPONIFICATION

This is a fancy name for making soaps. Fatty acids are esters, and can be hydrolysed to make soaps:

The IUPAC name for glycerol is 1, 2, 3 propan-triol.

AMIDE FORMATION

Esters can be used to make amides as well. Heat is required to complete the reaction.

POLYMERISATION

This will be a separate blog post. Polyesters are very useful polymers in the clothing industry, and to make drink bottles (PET).

Properties

Esters are insoluble in water. This is because they have a large non-polar part and cannot form hydrogen bonds with water. They do hydrolyse in water, forming the alcohol and carboxylic acid.

Their melting and boiling points are comparable to similar-sized aldehydes and ketones.