-        COO –

Definition

“Organic compounds that contain divalent functional group – COO – are called ester.”

General Formula

They are denoted by RCOOR where R may be any alkyl group. The alkyl groups of ester may be similar or different. The general formula of ester is:

C_nH_2n+1 – COO – C_nH_2n+1

Where n may be any natural number.

Structure

The structural formula of ester shows that it contains a Carbonyl group.

Formula

Examples

Formulae

Preparation

Ester can be prepared by the following methods:

1. Esterification of Alcohol

In presence of catalyst H₂SO₄, when Carboxylic Acid reacts with alcohol then ester is formed.

Chemical Properties

The important chemical reactions of ester are given below:

1. Hydrolysis in Presence of Acid

In presence of catalyst dilute H₂SO₄ when ester reacts with water then Carboxylic Acid and alcohol are formed.

2. Hydrolysis in Presence of Base

When ester reacts with 10% dilute NaOH then salt and alcohol are formed.

RCOOR + NaOH ® RCOONa + ROH

CH₃COOC₂H₅ + NaOH ® CH₃COONa + C₂H₅OH

Uses Of Carboxylic Acid

1.      It is used as a good solvent for paints, varnishes, oils, fats, gum, resins, cellulose etc.

2.      It is used as plasticizer.

It is used in the preparation of artifical flavours and essences.