Question

The alkane formed on heating sodium butanoate with sodalime is

• A. methane
• B. ethane
• C. propane
• D. butane

Answer 1

Answer: (C)

The alkane formed on heating sodium butanoate with sodalime is propane. In this reaction, the product contains one carbon atom less than the carboxylic acid. This process of elimination of carbon dioxide from a carboxylic acid is known as decarboxylation.

$\underset{\mathrm{Sodium}\mathrm{butanoate}}{\mathrm{CH}{}_3\mathrm{CH}{}_2\mathrm{CH}{}_2\mathrm{COO}{}^{-}\mathrm{Na}{}^{-}}+\mathrm{NaOH}\underset{\mathrm{\Delta }}{\overset{\text{CaO}}{\to }}\underset{\mathrm{Propane}}{\mathrm{CH}{}_3\mathrm{CH}{}_2\mathrm{CH}{}_3}+\mathrm{Na}{}_2\mathrm{CO}{}_3$