Performance of combined use of chlorosilanes and AlCl₃ in the carboxylation of toluene with CO₂

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• 作者：Xibao Zhang and Zhenmin Cheng
• 刊名：AIChE Journal
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：63
• 期：1
• 页码：185-191
• 全文大小：258K
• ISSN：1547-5905

文摘

Carboxylation of toluene with CO₂ for the production of p-toluic acid was shown to be promoted by the addition of Me₂PhSiCl, Ph₂SiCl₂, Ph₃SiH, or Ph₃SiCl into the AlCl₃ activated system, and the reaction activity was in the increasing order of Ph₂SiCl₂ < Me₂PhSiCl < Ph₃SiH < Ph₃SiCl. The spectrum of IR indicated that CO₂ could be effectively activated by AlCl₃ or Ph₃SiCl independently. DFT calculation was carried out to estimate the electrophilic potentials of the chlorine bridged AlCl₃···chlorosilane complex in the form of the APT atomic charges of Si and Al. The much higher activity of Ph₃Si-Cl···AlCl₃ over AlCl₃-AlCl₃ was considered due to its higher valences of Si and Al which are +2.107 and +1.833 compared with the +1.814 of Al in the latter. The mechanism of CO₂ activation under the action of double Lewis acid sites of Si and Al and the subsequent carboxylation of toluene was consequently proposed.