Well-Defined CeO<sub>2</sub> as Efficient Catalysts for the Green Synthesis of Pentamethylene Dicarbamate via Carbonylation of 1,5-Pentanediamine with Methyl Carbamate
Tiping Wei, Liguo Wang, Jiajun Zhang, Yan Cao, Xiang Hui, Jianhui Shi, Shuang Xu, Liyan Zhao, Peng He, Huiquan Li
Abstract
Bio-based pentamethylene dicarbamate (PDC) belongs to N-substituted carbamates, which are important fine chemicals and organic intermediates. In this work, well-defined CeO 2 rods, cubes, and octahedrons were successfully prepared to catalyze the synthesis of PDC by carbonylation of 1,5-pentanediamine (PDA) with methyl carbamate (MC). Among them, CeO 2 rods with higher amounts of acid–base sites and abundant oxygen vacancies showed superior intrinsic activity in the PDA carbonylation reaction. In situ FTIR results showed that intermediate polyureas were readily formed in the reaction, and then, CeO 2 rods promoted the alcoholysis of polyureas to PDC. In situ DRIFTS results indicated that the surface of CeO 2 rods is more favorable for the adsorption and activation of the reactants. CeO 2 rods can also be used for the efficient synthesis of a series of N-substituted carbamates. We believe that this work will contribute to the efficient, green, and sustainable production of N-substituted carbamates.