Organic Reaction Mechanisms 2016, the 52nd annual volume in this highly successful and unique series, surveys research on organic reaction mechanisms described in the available literature dated 2016. The following classes of organic reaction mechanisms are comprehensively reviewed: * Reaction of Aldehydes and Ketones and their Derivatives * Reactions of Carboxylic, Phosphoric, and Sulfonic Acids and their Derivatives * Oxidation and Reduction * Carbenes and Nitrenes * Nucleophilic Aromatic Substitution * Electrophilic Aromatic Substitution * Carbocations * Nucleophilic Aliphatic Substitution * Carbanions and Electrophilic Aliphatic Substitution * Elimination Reactions * Polar Addition Reactions * Cycloaddition Reactions * Molecular Rearrangements