Which method is used to prepare aldehydes from primary alcohols?

Primary alcohols are converted to aldehydes through an oxidation reaction. In this method, heating a primary alcohol with an oxidizing agent facilitates the transformation. Acidified potassium dichromate (K2Cr2O7) is a well-known oxidizing agent that selectively oxidizes primary alcohols to aldehydes.

During the reaction, the -OH group of the primary alcohol is oxidized, resulting in the formation of an intermediate that leads to the release of water and the formation of the carbonyl group characteristic of aldehydes. The use of acid in the potassium dichromate solution enhances the efficiency of the oxidation process and ensures complete conversion without over-oxidation to carboxylic acids, which is a common issue when stronger oxidizing conditions are applied.

In contrast, the other methods listed do not effectively yield aldehydes from primary alcohols.