How are aldehydes and ketones reduced to alcohols, and what are the catalysts used in catalytic hydrogenation?

Aldehydes and ketones are reduced to alcohols through catalytic hydrogenation, typically using hydrogen gas (H2) and a metal catalyst. Common catalysts include platinum (Pt), palladium (Pd), or nickel (Ni). During catalytic hydrogenation, the carbonyl group undergoes addition of hydrogen, resulting in the reduction of the carbon-oxygen double bond to form the corresponding alcohol. The metal catalyst facilitates the activation of hydrogen and promotes the reaction. This method provides a mild and selective way to convert aldehydes and ketones to alcohols without affecting other functional groups present in the molecule.