Bifunctional metal-salen complexes as efficient catalysts for the fixation of CO2 with epoxides under solvent-free conditions.
A bifunctional cobalt-salen complex containing a Lewis acidic metal center and a quaternary phosphonium salt unit anchored on the ligand effectively catalyzes the synthesis of cyclic carbonates from CO2 and epoxides under mild conditions without the utilization of additional organic solvents or co-catalysts. The effects of various reaction variables on the catalytic performance were studied in detail and indicate an optimized reaction temperature of about I00 degrees C and CO2 pressure of around 4 MPa, although the reaction proceeds smoothly even at pressures as low as 2 MPa. The catalyst is applicable to a variety of epoxides, producing the corresponding cyclic carbonates in good yields in most cases. Furthermore, the catalyst can be easily recovered and reused several times without significant loss of its catalytic activity. This process thus represents a greener pathway for the environmentally benign chemical fixation of CO2 to produce cyclic carbonates.
Miao
Cheng-Xia
CX
State Key Laboratory, Institute of Elemento-Organic Chemistry, Nankai University, Tianjin, China.
Wang
Jin-Quan
JQ
Wu
Ying
Y
Du
Ya
Y
He
Liang-Nian
LN
D002245:Carbon Dioxide / Q000737:chemistry* / Q000302:isolation & purification*; D002254:Carbonates / Q000737:chemistry; D002384:Catalysis; D003247:Conservation of Natural Resources; D003432:Cross-Linking Reagents / Q000737:chemistry*; D004852:Epoxy Compounds / Q000737:chemistry*; D017743:Equipment Reuse; D005029:Ethylenediamines / Q000737:chemistry*; D008024:Ligands; D008670:Metals / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010758:Phosphorus / Q000737:chemistry; D011312:Pressure; D012997:Solvents; D013696:Temperature
D002254:Carbonates; D003432:Cross-Linking Reagents; D004852:Epoxy Compounds; D005029:Ethylenediamines; D008024:Ligands; D008670:Metals; D009942:Organometallic Compounds; D012997:Solvents; D002245:Carbon Dioxide; D010758:Phosphorus; C011452:disalicylaldehyde ethylenediamine