Synthesis of 2-Butanol by Selective Hydrogenolysis of 1,4-Anhydroerythritol over Molybdenum Oxide-Modified Rhodium-Supported Silica

Rh-MoO_x/SiO₂ (Mo/Rh=0.13) is an effective catalyst for the hydrogenolysis of 1,4-anhydroerythritol (1,4-AHERY) and provides 2-BuOH in high yield of 51 %. This is the first report of the production of 2-BuOH from 1,4-AHERY by hydrogenolysis. 1,4-AHERY was more suitable as a starting material than erythritol because the 2-BuOH yield from erythritol was low (34 %). Based on the kinetics and comparison of reactivities of the related compounds using Rh-MoO_x/SiO₂ and Rh/SiO₂ catalysts, the modification of Rh/SiO₂ with MoO_x leads to the high activity and high selectivity to 2-BuOH because of the generation of reactive hydride species and the strong adsorption of 1,4-AHERY on MoO_x species. The reaction proceeds by main two routes, (I) the combination of single C−O hydrogenolysis with the desorption of intermediates, a usual route in hydrogenolysis, and (II) multiple C−O hydrogenolysis without the desorption of intermediates from the active site, and the reaction mechanism for Route (II) is proposed.