Versatility of Boron-Mediated Coupling Reaction of Oxetanes and Epoxides with CO2: Selective Synthesis of Cyclic Carbonates or Linear Polycarbonates
Type
ArticleAuthors
Zhang, Cheng JianWu, Shao Qi
Boopathi, Senthil
Zhang, Xing Hong

Hong, Xin
Gnanou, Yves

Feng, Xiaoshuang
KAUST Department
Academic AffairsChemical Science Program
Office of the VP
Physical Science and Engineering (PSE) Division
Date
2020-08-05Online Publication Date
2020-08-05Print Publication Date
2020-08-31Embargo End Date
2021-08-05Submitted Date
2020-06-29Permanent link to this record
http://hdl.handle.net/10754/665752
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Show full item recordAbstract
Achieving simultaneously high selectivity and high rate in the coupling reaction of CO2 with poorly reacting oxetanes remains a major challenge. Here, the selective and nearly quantitative conversion of the coupling reaction of oxetanes with CO2 into six-membered cyclic organic carbonates (COCs) is described, when a binary metal-free system composed of commercially available alkyl borane and onium iodide salts is used under 10 bar CO2 pressure between 90 and 110 °C. Kinetic investigations provide quantitatively the enthalpy and entropy of activation [ΔH‡ = 6.7 ± 1.2 kcal/mol and ΔS‡ = -57 ± 4 cal/(mol·K)] of the back-biting, cyclic formation reaction. In addition to forming borate complexes with the anions responsible for the CO2/oxetane coupling reaction, these alkyl boranes activate the cyclic ethers as unambiguously confirmed by density functional theory studies. Upon selecting onium salts other than iodide-based ones, in particular those with poor leaving ability, the process is driven toward chain growth and the formation of linear polycarbonates. This metal-free system also exhibits both versatility and an activity comparable to that of metal catalysts (turnover frequency values of 14-124 h-1) for the synthesis of various five-membered COCs from epoxides and CO2.Citation
Zhang, C.-J., Wu, S.-Q., Boopathi, S., Zhang, X.-H., Hong, X., Gnanou, Y., & Feng, X.-S. (2020). Versatility of Boron-Mediated Coupling Reaction of Oxetanes and Epoxides with CO2: Selective Synthesis of Cyclic Carbonates or Linear Polycarbonates. ACS Sustainable Chemistry & Engineering, 8(34), 13056–13063. doi:10.1021/acssuschemeng.0c04768Sponsors
X.-H.Z. gratefully acknowledges financial support of the National Science Foundation of People’s Republic of China (nos. 51973190 and 21774108). X.H. is grateful for financial support from the National Natural Science Foundation of China (21702182, 21873081) and the Fundamental Research Funds for the Central Universities (2-2050205-19-361). C.-J.Z. acknowledges support of KAUST for his stay in Gnanou’s laboratoryPublisher
American Chemical Society (ACS)Additional Links
https://pubs.acs.org/doi/10.1021/acssuschemeng.0c04768ae974a485f413a2113503eed53cd6c53
10.1021/acssuschemeng.0c04768