Efficient synthesis of cyclic carbonate from carbon dioxide catalyzed by polyoxometalate: the remarkable effects of metal substitution

Abstract

Tetraalkylammonium salts of transition-metal-substituted polyoxometalates, such as [( n-C 7H 15) 4N] 6[ α-SiW 11O 39Co] and [( n-C 7H 15) 4N] 6[ α-SiW 11O 39Mn], efficiently catalyze cyclic carbonate synthesis from carbon dioxide and epoxide. The catalytic activity is significantly influenced by the type of transition metal and the countercation (Co 2+ ≈ Mn 2+ > Ni 2+ > Fe 3+ ≫ Cu 2+; ( n-C 7H 15) 4N + > ( n-C 4H 9) 4N + ≫ K +). Co- or Mn-substituted catalysts required neither additional organic solvents nor additives. Thus, polyoxometalates are promising as nonhalogen anionic components of catalysts for cyclic carbonate synthesis.