Calcium-Based Catalytic System for the Synthesis of Bio-Derived Cyclic Carbonates under Mild Conditions
作者:Lars Longwitz、Johannes Steinbauer、Anke Spannenberg、Thomas Werner
DOI:10.1021/acscatal.7b03367
日期:2018.1.5
Recently, bio-derived cyclic carbonates have gained significant importance: e.g., as building blocks in non-isocyanate polyurethanes (NIPUs). Herein we report the development of a calcium-based catalyst system for the synthesis of challenging internal and trisubstituted cyclic carbonates from bio-derived epoxides and CO2 under mild reaction conditions. Several crown ethers were tested as ligands in
近来,生物来源的环状碳酸酯已变得非常重要:例如,作为非异氰酸酯聚氨酯(NIPU)中的结构单元。本文中,我们报告了在温和的反应条件下,由生物衍生的环氧化物和CO 2合成具有挑战性的内部和三取代的环状碳酸酯的钙基催化剂系统的开发。测试了几种冠醚作为配体与各种助催化剂的配体,以活化CO 2。活性最高的系统除碘化钙外,还由二环己基官能化的18冠-6醚和三苯基膦组成。用1检测到冠状醚在原位络合Ca 2+。1 H NMR光谱。有趣的是,加入三苯基膦作为助催化剂可显着提高活性,这与有机超碱(如DBU和TBD)的活性相似或什至更高。该催化体系用于将16种不同的生物衍生环氧化物(包括脂肪酸酯,油和萜烯)与CO 2进行转化,并能够在温和条件下促进反应。各种内部环氧化物仅在45℃,0.5 MPa CO 2压力,5摩尔%的催化剂负载量和24小时的反应时间下转化,分离出的收率最高为相应碳酸盐的98%。尽管需要更苛刻