Catalytic reduction of 1,4‐benzoquinone to hydroquinone via [FeFe]‐hydrogenase model complexes under mild conditions

Abstract

AbstractBACKGROUNDHydroquinone (HQ) is an important fine chemical raw material and intermediate, which is widely used in chemistry industry. It is great significance to develop a new environmentally‐friendly synthesis method to produce HQ.RESULTSThree [FeFe]‐hydrogenase model complexes (μ‐budt)[Fe(CO)3]2[1; budt = SCH(CH3)CH2CH2)S], (μ‐budt)[Fe(CO)3][Fe(CO)2PPh3](2), and (μ‐bust)[Fe(CO)3]2 [3; bust = SCH(CH3)CH2CH2)S(O)] were synthesized by direct CO/L substitution or sulfur based oxygenation. The synthesized new complexes were fully characterized by FT‐IR, 1H NMR, 13C NMR and X‐ray crystallography. The electrochemical properties of these model complexes were investigated by cyclic voltammetry in CH2CI2 to evaluate the redox properties of the iron atoms. It was indicated that these new complexes are not only electrochemical catalysts for proton reduction of hydrogen, but also efficient catalysts for catalytic the transfer hydrogenation of BQ (1, 4‐benzoquinone) to prepare HQ under mild conditions. Especially,complex 2 exhibited the highest catalytic activity for reduction of BQ with methanol as the proton source, which gave a BQ conversion of 91 % and 72 % selectivity for HQ.CONCLUSIONSThe complex 2 can be a new type catalyst for catalytic reduction of BQ to HQ under mild reaction conditions. In addition, the Kinetics and mechanism were also investigated for a proposed transfer hydrogenation process. © 2019 Society of Chemical Industry