Mild catalytic multiphase hydrogenolysis of benzyl ethers

Abstract

A preliminary study was conducted on the multiphase (aqueous KOH–isooctane–Aliquat^® 336) hydrogenolysis of benzyl methyl ether using Pd/C, Pt/C and Raney-Ni as catalysts, under mild conditions (T = 50 °C, pH₂ = 1 atm). Using ethanol as solvent, the Pd/C system is very efficient, while the same catalyst under multiphase conditions is almost inactive. With Pt/C, the reaction is always sluggish, and ring hydrogenation kicks in under multiphase conditions. The Raney-Ni system has an opposite behavior, while debenzylation is slow in ethanol, under multiphase conditions the reaction is quite fast. Other O-benzyl protected substrates undergo debenzylation with Raney-Ni as well, with varying chemoselectivity.