The Pinacol-Pinacolone rearrangement and the Beckmann rearrangement are two different organic reactions that involve the rearrangement of molecular structures to form new products. Here, I will describe the mechanisms and the structures of reactants, intermediates, and products for both reactions.1. Pinacol-Pinacolone rearrangement:The Pinacol-Pinacolone rearrangement is a reaction that involves the conversion of a 1,2-diol pinacol to a ketone pinacolone in the presence of an acid catalyst.Mechanism:a Protonation of the hydroxyl group by the acid catalyst.b Intramolecular migration of the neighboring carbon group with the simultaneous loss of a water molecule, forming a carbocation intermediate.c Deprotonation of the carbocation by a base, forming the final ketone product.Reactant: 1,2-diol pinacol Intermediate: CarbocationProduct: Ketone pinacolone 2. Beckmann rearrangement:The Beckmann rearrangement is a reaction that involves the conversion of an oxime to an amide or a nitrile in the presence of an acid catalyst and a dehydrating agent.Mechanism:a Protonation of the hydroxyl group of the oxime by the acid catalyst.b Intramolecular migration of the neighboring carbon group with the simultaneous loss of a water molecule, forming a nitrilium ion intermediate.c Nucleophilic attack by water or another nucleophile on the nitrilium ion, forming the amide or nitrile product.Reactant: OximeIntermediate: Nitrilium ionProduct: Amide or NitrileIn summary, the Pinacol-Pinacolone rearrangement involves the conversion of a 1,2-diol to a ketone, while the Beckmann rearrangement involves the conversion of an oxime to an amide or a nitrile. The mechanisms of both reactions involve intramolecular migration of a carbon group and the formation of different intermediates carbocation in Pinacol-Pinacolone and nitrilium ion in Beckmann rearrangement .