Synthesis and characterization of bis[2-(1H-benzimidazol-2-yl)benzoato]nickel(II), and its use for preparation of dimethyl carbonate from methanol and CO2

Abstract

A new complex, bis[2-(1H-benzimidazol-2-yl)benzoato]nickel(II) (NiL2), has been synthesized and characterized. It was used as catalyst for synthesis of dimethyl carbonate (DMC) from methanol and CO2 in the presence of dicyclohexyl carbodiimide (DCC) as promoter. The effects of temperature, reaction time, and amount of catalyst on the reaction, and the reusability of the catalyst, were investigated. A catalytic mechanism is proposed. The results revealed that NiL2 + DCC had excellent catalytic activity, because this catalytic system promoted facile formation of DMC, with acceptable yield, in the presence of a small amount of NiL2 and under moderate conditions (80 °C, 1.0 MPa). Moreover, the catalyst has been consecutively used five times without significant loss of activity.