Soda-Lime Decarboxylation

$$\text{R--COONa} + \text{NaOH} \xrightarrow{\text{CaO}, \, \Delta} \text{R--H} + \text{Na}_2\text{CO}_3$$

Concept: Sodium salts of carboxylic acids undergo loss of a carbon dioxide molecule ($$\text{CO}_2$$) when heated with soda-lime, yielding an alkane with one carbon atom less than the parent carboxylic acid.

Reagents & Role of CaO:

• Soda-lime is a mixture of $$\text{NaOH}$$ and $$\text{CaO}$$ in a 3:1 mass ratio. Calcium oxide ($$\text{CaO}$$) keeps sodium hydroxide ($$\text{NaOH}$$) dry because $$\text{NaOH}$$ is deliquescent, and it prevents glass apparatus from fusing at high temperatures.