Well-Defined Cesium Benzotriazolide as an Active Catalyst for Generating Disubstituted Ureas from Carbon Dioxide and Amines

Abstract

The reaction of alkali metal carbonates with various azole compounds produced a new series of alkali metal azolides, and they were applied as active catalysts for the production of disubstituted ureas from the carboxylation of various amines with CO2. Among them, cesium benzotriazolide (Cs[BTd]) was found to be the most active for the carboxylation reaction and was structurally characterized by single-crystal X-ray diffraction. The crystal structure of highly hygroscopic Cs[BTd] was found to be [BTA]center dot center dot center dot Cs[BTd], which explains why it is a water-tolerant active species for this carboxylation reaction, leading to a maximum turnover frequency of 344 h(-1) as well as high recyclability even after five successive runs.