How to Prepare Butane by Decarboxylation Method?

Butane can be prepared from decarboxylation method from pentanoic acid. Pentanoic acid is a carboxylic acid. In carboxylation reaction, one carbon atom in the carboxylic acid is removed to give the alkane as the product. Butane has four carbon atoms. Therefore we have to use a carboxylic acid which have five carbon atoms.

carboxylic acid to alkane - decarboxylation

Decarboxylation of carboxylic acids

Decarboxylation is used to reduce any carboxylic acids to hydrocarbon (alkanes). Sodalime mixture is used as the reagent in the decarboxylation. Carboxylic acid can be an aliphatic or aromatic one. This is one method of preparing alkanes from carboxylic acids by a single step. But note that, to give an alkane that has one carbon fewer than the starting carboxylic acid.

Sodalime mixture - NaOH / CaO

In carboxylation, carboxylic group is eliminated to give hydrocarbon

_COOH group of carboxylic acid is eliminated. Therefore number of carbon atoms is reduced by one. So we have to use a carboxylic acid which has five carbon atoms. It is pentanoic acid / Valeric acid / CH3CH2CH2CH2COOH.

Pentanoic acid to butane

Pentanoic acid reacts with sodalime to give butane. Mixture should be heated to get the product.

Pentanoic acid to butane - decarboxylation

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