(86f) Efficient Synthesis of Cyclic Carbonates from Atmospheric CO2 Using a Positive Charge Delocalized Ionic Liquid Catalyst

Zhiguo Zhang^a,*, Fangjun Fan^a, Huabin Xing^a, Qiwei Yang^a, Zongbi Bao^a, Qilong Ren^a

^a Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University, Zheda Road 38, Hangzhou 310027, China.

E-mail: zhiguo.zhang@zju.edu.cn

Chemical conversion of carbon dioxide into value-added chemicals has seen an explosion of interest in current synthetic realm since CO₂ represents a ubiquitous, renewable, and inexpensive C1 feedstock.[1] Among various transformations, the coupling of epoxides with CO₂ to form five-membered cyclic carbonates has long been considered to be one of the most promising routes for the large-scale utilization of CO₂.[2] Although significant advances have been achieved in this field, it is still a challenge to perform the reaction with atmospheric CO₂ or flue gas. In this study, we described the development of positive charge delocalized pyridinium as a highly efficient and recyclable organocatalyst for the formation of cyclic carbonates from CO₂ and epoxides.[3] In addition, a systematic investigation of cation structures on the catalytic activities provided a proof-of-concept that the excellent catalytic performance of protic onium slats is attributed to the enhanced synergistic interplay of acidic proton and bromide to epoxides and CO₂ through positive charge delocalization on its cation. This protocol is compatible with a plethora of terminal epoxides and consequently provides a practical alternative method for the fixation of industrial CO₂ into value-added cyclic carbonates.

Acknowledgement:

The authors are grateful to the financial support from the National Key R&D Program of China (2016YFA0202900), the National Natural Science Foundation of China (21376212, 21436010),.

References:

[1] Cokoja, M., Wilhelm, M. E., Anthofer, M. H. W., Herrmann, A., Kühn, F. E. ChemSusChem. 2015, 8, 2436.

[2] He, Q., O'Brien, J. W., Kitselman, K., Tompkins, A. L. E., Curtis, G. C. T., Kerton, F. M. Catal. Sci. Technol. 2014, 4, 1513.

[3] Zhang, Z, Fan, F, Xing, H, Yang, Q, Bao, Z, Ren, Q. ACS Sustainable Chem. Eng., 2017, 5, 2841.