Complete the reactions to show how butanoic acid may be converted to butanal.

Butanoic Acid is converted to Butanal in two steps;

Step 1: Conversion of Butanoic Acid into Butyryl Chloride:

Butanoic Acid when treated with Thionyl Chloride gives Butyryl Chloride, SO₂ and HCl gases. This step is selected due to conversion of a bad leaving group (-OH) into a good leaving group (-Cl).

Step 2: Conversion of Butyryl Chloride to Butanal:

In this reaction the Butyryl Chloride is reduced to Butanal by treating Butyryl Chloride with a mild reducing agent i.e. Lithium tri tert-butoxy aluminum hydride.