Carbon Dioxide Cycloaddition to Epoxides: A Comparative Study on the Catalytic Activities of Two Binary Catalysts VIVO(N2O2)/TBAB and VVO2(O2N)/TBAB and In Situ Derivation of a Bifunctional Catalyst

• Published in: Catalysis letters 2024-03, Vol.154 (3), p.1081-1093
• Main Authors: Borah, Rakhimoni, Deori, Naranarayan, Lahkar, Surabhi, Paul, Saurav, Brahma, Sanfaori
• Format: Article
• Language: English
• Subjects: Carbon dioxide; Carbonates; Catalysis; Catalysts; Cations; Chemistry; Chemistry and Materials Science; Comparative studies; Cycloaddition; Energy consumption; Epichlorohydrin; Functional groups; Imidazole; Industrial Chemistry/Chemical Engineering; Ligands; Organometallic Chemistry; Physical Chemistry; Substrates
• ISSN: 1011-372X; 1572-879X
• DOI: 10.1007/s10562-023-04367-2

A comparative study is illustrated on the catalytic activities of two structurally very different vanadium complexes, one oxovanadium(IV) complex 1 , V IV O(N 2 O 2 ) and the other dioxovanadium(V) complex 2 , V V O 2 (O 2 N) for the carbon dioxide cycloaddition to epoxides to yield cyclic carbonates. The binary catalyst, 1/TBAB is found to be non-selective towards the size of the epoxide substrates showing 90–100% conversions to cyclic carbonate products under the reaction conditions [60 °C, 5 bar ( p CO 2 ),  4 h]. However, the other binary catalyst, 2/TBAB having bulky tetrabutylammonium counter cation, could show selectivity resulting only 52% (allyl glycidyl ether), 63% (butyl glycidyl ether) and 54% (1-hexene oxide) conversions for longer tailed epoxides, on contrary to the  99% (epibromohydrin) and  88% (epichlorohydrin) conversions for shorter tailed epoxides. Further, taking the advantage of the modifiability of bromo functional group to imidazolium bromide functionality, the bromo functional group containing oxovanadium(IV) complex 1 has been affixed with imidazolium bromide functionality on reaction with N -methyl imidazole, and thus transformed to a bifunctional catalyst, 1A•Br . This in situ formed bifunctional catalyst, 1A•Br during the course of catalytic reaction, also showed to be an active catalyst system resulting in 100% conversion under the reaction conditions [60 °C, 5 bar ( p CO 2 ), 12 h]. Graphical Abstract VIVO(N 2 O 2 ) shows no substrate discrimination in the cycloaddition of CO 2 to epoxides, while anionic VVO 2 (O 2 N) having bulky tetrabutyl ammonium counter cation shows. Low conversions to cyclic carbonates are found for epoxides with longer tails compared to shorter tailed ones, when VVO 2 (O 2 N) is employed as a catalyst component. In situ modification of bromo functionalised ligand containing complex VIVO(N 2 O 2 ) to a bifunctional catalyst via introducing imidazoliumbromide functionalities.