Explain the following reaction: Aldol condensation

Aldehydes or ketones having α -hydrogen atom react with dilute base like sodium hydroxide, its two molecules condense to form β -hydroxy aldehydes or β -hydroxy ketones. The obtained product is called aldol because it contains both aldehyde and alcohol groups and the reaction is called aldol condensation. Example:

Explain the following reaction: Cannizzaro reaction

Cannizzaro's reaction: The self oxidation-reduction (disproportionation) reaction of aldehydes which do not have α -hydrogen atom, on treatment with concentrated alkali is known as the Cannizzaro's reaction. In this reaction, two molecules of aldehydes participate where one is reduced to alcohol and the other is oxidised to carboxylic acid. For example, when methanal is treated with concentrated potassium hydroxide, methanol and potassium methanoate are produced. 2 HCHO → Con . KOH CH 3 OH + HCOOK

How will you bring about the following conversion: Benzaldehyde to benzophenone?

Benzaldehyde on oxidation with acidified potassium permanganate gives benzoic acid. Benzoic acid undergoes decarboxylation on heating with sodalime, and forms benzene. Benzene on Friedel-Craft's benzoylation with benzoyl chloride in the presence of anhydrous AlCl 3 catalyst forms benzophenone. The reactions are given below: