Gas-phase reduction of cyclic and acyclic α,β-unsaturated ketones by hydrogen transfer on MgO. Effect of the ketone structure

摘要: Abstract The gas-phase hydrogen transfer reduction (HTR) of cyclic and acyclic α,β-unsaturated ketones to the corresponding unsaturated alcohols (UOL) using 2-propanol as donor was studied on MgO an alternative less selective conventional hydrogenation high pressure H2. HTR 2-cyclohexenone mesityl oxide were used model reactions. activity selectivity toward alcohol depended ketone chemical structure. Cyclic in fact reactive but more UOL formation than oxide, yielding about 85% (91% selectivity) at 573 K. rigid structure enforces a s-trans conformation that favors C O bond thereby enhances formation. In contrast, affords simultaneous both bonds, O, forming also saturated alcohol; consequence, maximum yields 45% (47% obtained 573 K from oxide. conversion pathways other compounds formed primary product reactants via six-membered intermediate according Meerwein–Ponndorf–Verley mechanism. However produced by consecutive reactions directly reduction. Reduction negligible regardless reactant whereas competing such shift likely contribute during reactant.