摘要
A series of zwitterionic‐type quaternary ammoniums(ZTQAs)with varying lengths of alkyl chains combined with KI were synthesized and considered as catalysts for the coupling reaction of CO2 and various terminal epoxides.The prolonged alkyl chain of ZTQAs exhibited temperature‐responsive self‐separation in propylene carbonate(PC).The interaction between ZTQAs and KI was confirmed by X‐ray photoelectron spectroscopy and quantum chemical calculations.This interaction strengthened the nucleophilicity of the I?ion,favoring the catalytic reaction.The 3‐(dimethyltetradecylammonium)propane sulfonate(DTPS)/KI showed an excellent yield of PC(95.1%)at 125°C,1.5 MPa,and 1 mol%loading of catalyst.The precipitate formed spontaneously from the catalytic system,providing high catalytic activity of the homogeneous catalyst,as well as easy recovery of the heterogeneous catalyst.
随着在世界各国工业化进程不断加快,人类对煤、石油、天然气等化石燃料的需求越来越大,既加速了能源短缺,又排放了大量CO_2.CO_2又成为分布最广、价格便宜和储量丰富的碳资源.人类除了努力做到CO_2减排,又可将其转化为能源、材料和各种化工产品.CO_2与环氧化合物发生偶联反应生成环碳酸酯,具有原子经济性,符合绿色化学的观点,是最有前景的方法之一.CO_2可以与三元环氧化合物发生偶联反应生成五元环状碳酸酯,它是当今合成环碳酸酯比较成熟的方法.已经被设计合成并应用的高效催化体系有离子液体催化剂、金属盐或氧化物催化剂、有机催化剂、希夫碱金属配合物催化剂以及大环金属配合物催化剂等等,但最有效的催化剂还是均相催化剂,其最大的缺点在于催化剂和产物分离困难.既有均相催化剂高的催化活性,又能像多相催化剂易于分离,是人们设计新催化剂的目标.本文设计合成了一系列含有不同烷基链长度的两性离子型季铵盐(ZTQAs),可以与KI协同催化CO_2与环氧化合物偶联反应.随着烷基链的增长,ZTQAs在碳酸丙烯酯中表现出温度调控的自分离特性.通过X射线光电子能谱和量子化学计算证实,ZTQAs与KI之间存在明显的相互作用,从而增强了碘离子的亲核能力.当反应条件为125 ℃,CO_2压力1.5 MPa以及1mol%催化剂用量下,DTPS/KI催化剂取得了良好的收率(95.1%).并且该催化剂可以从催化系统中自发的析出,因而既表现出均相催化剂的高活性,又可以像非均相催化剂那样循环使用.
基金
supported by the National Natural Science Foundation of China(41330317,21403051)
the Natural Science Foundation of Hebei province(B2016402030,B2017402079)
the Science and Technology Foundation of Universities of Hebei Province(ZD2015113)
the Science and Technology Research Development Program of Handan(1621211041-3,1622201049-2)
the Program for One Hundred Innovative Talents in Universities of Hebei Province(BR2-204)~~
作者简介
付西英,共同第一作者.;谢鹏涛,共同第一作者.;常涛,通讯联系人.电话/传真:(0310)8578760;电子信箱:changtao@hebeu.edu.cn。;通讯联系人,秦身钧.电话/传真:(0310)8577902;电子信箱:qinsj528@hebeu.edu.cn。
