Issue 15, 2018

CO2 promoted synthesis of unsymmetrical organic carbonate using switchable agents based on DBU and alcohols

Abstract

1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is an effective nucleophilic catalyst for the transesterification of dimethyl carbonate (DMC) with various alcohols and amines, which afforded unsymmetrical organic carbonate and carbamate. It was observed that the transesterification was accelerated under pressurized CO2 in this work. The activity is very high and the best result (89% conversion with 98% selectivity to unsymmetrical carbonate) was obtained for the DBU/alcohol/DMC/CO2 system. The addition of CO2 to DBU/ethanol generated the DBU cation salt, [DBUH][OCOOCH2CH3], which dissociated more favorably under increasing reaction temperature even under pressurized CO2. The salt could also help to activate DMC by H-bond interaction. The reaction system can be extended easily for the catalytic synthesis of carbamates from amines and DMC. After the reaction, the salt was separated from the reaction mixture and DBU can be recovered by the feasible thermal decomposition, offering a straightforward strategy for the recycling of DBU. On the basis of these results, a plausible mechanism involving the role of both DBU and CO2 has been proposed.

Graphical abstract: CO2 promoted synthesis of unsymmetrical organic carbonate using switchable agents based on DBU and alcohols

Supplementary files

Article information

Article type
Paper
Submitted
07 Apr 2018
Accepted
26 Jun 2018
First published
27 Jun 2018

New J. Chem., 2018,42, 13054-13064

CO2 promoted synthesis of unsymmetrical organic carbonate using switchable agents based on DBU and alcohols

Q. Gu, J. Fang, Z. Xu, W. Ni, K. Kong and Z. Hou, New J. Chem., 2018, 42, 13054 DOI: 10.1039/C8NJ01638K

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