Consider the following statements regarding the preparation of aldehydes and ketones: I. Stephen reaction involves the reduction of nitriles with SnCl ₂ and HCl followed by hydrolysis to give aldehydes. II. Etard reaction involves the oxidation of toluene to benzaldehyde using chromyl chloride. III. Treatment of acyl chlorides with dialkylcadmium yields aldehydes. IV. Hydration of propyne in the presence of dilute H

Step-by-step solution

Statement I is correct. Nitriles are reduced to the corresponding imine with stannous chloride in the presence of hydrochloric acid, which on hydrolysis gives the corresponding aldehyde (Stephen reaction). Statement II is correct. Chromyl chloride oxidises the methyl group of toluene to a chromium complex, which on hydrolysis gives benzaldehyde (Etard reaction). Statement III is incorrect. Treatment of acyl chlorides with dialkylcadmium yields ketones, not aldehydes. Statement IV is incorrect. Hydration of propyne