NCEA Level 3 Organic Chemistry Reaction Schemes Practice Test

Reducing aldehydes and ketones relies on hydride donors delivering a hydrogen to the carbonyl carbon, turning the C=O into an alcohol after workup. Sodium borohydride and lithium aluminum hydride are classic sources of hydride for this transformation. Sodium borohydride is milder and efficiently reduces both aldehydes (to primary alcohols) and ketones (to secondary alcohols) in typical solvents. Lithium aluminum hydride is stronger but achieves the same carbonyl reductions readily as well, though it can act on more functional groups under broader conditions. Because either reagent can accomplish the reduction of both types of carbonyls, the best answer is that sodium borohydride or lithium aluminum hydride can do it. Hydrogenation with H2 and a Pd catalyst is a different route and is not as universally reliable for these carbonyl reductions under standard conditions.