12.1: Structure of the Carbonyl Group 12.2: Oxidation of Aldehydes and Ketones This page looks at ways of distinguishing between aldehydes and ketones using oxidizing agents such as acidified potassium dichromate(VI) solution, Tollens' reagent, Fehling's solution and Benedict's solution. 12.3: Reduction of Carbonyls to Alcohols Using Metal Hydrides The most common sources of the hydride nucleophile are lithium aluminum hydride and sodium borohydride. In metal hydrides reductions the resulting alkoxide salts are insoluble and need to be hydrolyzed (with care) before the alcohol product can be isolated. In the sodium borohydride reduction the methanol solvent system achieves this hydrolysis automatically. In the lithium aluminum hydride reduction water is usually added in a second step. 12.4: Spectroscopic Properties of Aldehydes and Ketones