Synthesis of Cyclic Carbonates Catalysed by Aluminium Heteroscorpionate Complexes

Javier Martínez, José A. Castro-Osma, Amy Earlam, Carlos Alonso-Moreno, Antonio Otero, Agustín Lara-Sánchez*, Michael North, Antonio Rodríguez-Diéguez

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

New aluminium scorpionate based complexes have been prepared and used for the synthesis of cyclic carbonates from epoxides and carbon dioxide. Bimetallic aluminium(heteroscorpionate) complexes 9-14 were synthesised in very high yields. The single-crystal X-ray structures of 12 and 13 confirm an asymmetric κ<sup>2</sup>-NO-μ-O arrangement in a dinuclear molecular disposition. These bimetallic aluminium complexes were investigated as catalysts for the synthesis of cyclic carbonates from epoxides and carbon dioxide in the presence of ammonium salts. Under the optimal reaction conditions, complex 9 in combination with tetrabutylammonium bromide acts as a very efficient catalyst system for the conversion of both monosubstituted and internal epoxides into the corresponding cyclic carbonates showing broad substrate scope. Complex 9 and tetrabutylammonium bromide is the second most efficient aluminium-based catalyst system for the reaction of internal epoxides with carbon dioxide. A kinetic study has been carried out and showed that the reactions were first order in complex 9 and tetrabutylammonium bromide concentrations. Based on the kinetic study, a catalytic cycle is proposed.

Original languageEnglish
Pages (from-to)9850-9862
Number of pages13
JournalChemistry : A European Journal (Weinheim an der Bergstrasse, Germany)
Volume21
Issue number27
DOIs
Publication statusPublished - 26 Jun 2015

Keywords

  • aluminium complexes
  • carbon dioxide
  • catalysis
  • cyclic carbonates
  • epoxides

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