Solventless synthesis of propylene carbonate catalysed by chromium–salen complexes: Bridging homogeneous and heterogeneous catalysis

Mixed‐Linker Metal‐Organic Frameworks as Catalysts for the Synthesis of Propylene Carbonate from Propylene Oxide and CO2

“…Especially salen, phthalocyanin or porphyrin complexes of transition metals (e.g. Cr, [30] Co [31,32] Ni, [33] Cu, [31] Zn [31,34] ) or main group elements such as aluminum [35,36] or tin [37] were found to be highly active. Coordination of the epoxide at the metal center via its oxygen atom is generally assumed to be the first step of the catalytic cycle.…”

“…[42] To overcome the problems of catalyst separation with these systems, efforts in the application of heterogeneous catalysts have been undertaken. One main strategy concerned the immobilization of homogeneous catalysts onto solid supports, [30,34,43,44] but also metal oxides, like ZnO/ SiO 2 [45] or MgO, [46] catalyzed the reaction. In addition, porous materials like MCM-41, [47] Cs zeolites [48] or aminefunctionalized Ti(Al)-SBA-15 [49] were used.…”

A mini review on chemical fixation of CO2: Absorption and catalytic conversion into cyclic carbonates

“…The synthesis of cyclic carbonates through cycloaddition of CO 2 to epoxides is one of the few commercial routes that use CO 2 as a raw material (Scheme 5). In the past decades, a number of homogeneous and heterogeneous catalysts have been developed for the cycloaddition reaction, such as phosphines [32][33][34], organic bases [35][36][37], ionic liquids [1,[38][39][40][41][42][43], organometallic complexes [44][45][46][47][48][49][50][51][52][53][54][55][56][57][58], metal oxides [59][60][61][62][63][64], modified zeolites and smectites [65][66][67][68][69], and supported catalysts [70][71][72][73][74][75][76][77]. There are reports on organometallic complexes of Cr, Co, Ni, Al, Mn, Zn, Ru, Re...…”

Coupling reaction of carbon dioxide and epoxides efficiently catalyzed by one-component aluminum–salen complex under solvent-free conditions

“…However, TOF was very low (10.3-13.3) at 25 8C. The chromium-salen complexes of Ramin et al [49] showed propylene carbonate TOF of 90-330 h À1 at 140 8C. Complex 2c shows the lowest catalytic performance among the complex 2a-d, but its TOF is still up to 534 h À1 , which is much more effective than the 2f-BTPC binary catalyst (entry 7).…”

“…A possible interpretation is that steric hindrance of phenyl at the R1 and R2 positions and concomitant deformation of the planar ring structure occurred, inhibiting resonance in the chelate ring and playing a predominant role in contributing factor with respect to inductive effect of phenyl group. As a matter of fact, no general agreement exists as to whether phenyl groups are electron repelling or electron withdrawing, since it depends somewhat on the ligand type and the group's substituted position in the ligand [34,[49][50][51][52][53][54]. Significantly, this kind of novel salenAl(III)Cl bifunctional catalyst is extremely stable to moisture and robust to impurities.…”