Bifunctional Catalysts Based on m‐Phenylene‐Bridged Porphyrin Dimer and Trimer Platforms: Synthesis of Cyclic Carbonates from Carbon Dioxide and Epoxides

Abstract

Highly active bifunctional diporphyrin and triporphyrin catalysts were synthesized through Stille coupling reactions. As compared with a porphyrin monomer, both exhibited improved catalytic activities for the reaction of CO2 with epoxides to form cyclic carbonates, because of the multiple catalytic sites which cooperatively activate the epoxide. Catalytic activities were carefully investigated by controlling temperature, reaction time, and catalyst loading, and very high turnover number and turnover frequency were obtained: 220 000 and 46 000 h(-1) , respectively, for the magnesium catalyst, and 310 000 and 40 000 h(-1) , respectively, for the zinc catalyst. Results obtained with a zinc/free-base hybrid diporphyrin catalyst demonstrated that the Br(-) ions on the adjacent porphyrin moiety also function as nucleophiles.

Metalated porous porphyrin polymers as efficient heterogeneous catalysts for cycloaddition of epoxides with CO2 under ambient conditions

“…For this reaction, a number of homogeneous catalysts such as ionic liquids [5,6], alkali metal halides [7], metal salen complexes [8][9][10][11][12][13], and metalloporphyrins [14][15][16][17][18], and heterogeneous catalysts such as metal oxides [19][20][21], zeolites [22,23], ion-exchanged resins [24], mesoporous materials [25][26][27], nanoporous polymers [28,29], and metalorganic frameworks (MOFs) [30,31] have been employed. Notably, most of these catalysts normally require harsh conditions such as relatively high temperature, high CO 2 pressure, and high catalyst loadings.…”

[Cp2Mo(OH)(OH2)]+‐Catalyzed Hydrolysis of Mono‐ and Difunctional Ethers: Theoretical Understanding of Their Divergent Reactivity

“…One way to make chemistry less polluting is to find alternatives to the organic solvents frequently used . Several research lines are underway today: reactive systems “without solvent”, immobilization of solvents, ionic liquids, biphasic solvents, and harmless and renewable solvents like CO 2 and H 2 O . The aqueous reaction medium is the classic alternative to organic solvents because water is cheap, abundant, and harmless, but also has many unique physical and chemical properties: wide range of temperatures for liquid state, high dielectric constant, extensive hydrogen bonds, high heat capacity, and optimal oxygen solubility to maintain aquatic life forms.…”

Desulfinative palladium‐catalyzed cross‐coupling of arylsulfonyl hydrazides with aryl bromides under air

“…Catalysis using palladium as the transition metal is certainly one of the most modern and powerful strategies for aryl–aryl bond formation, and the development of a new Pd‐catalyzed system has aroused vigorous interest. The most frequently employed methods for the synthesis of unsymmetrical biphenyl derivatives are Suzuki, Stille and Hiyama cross‐coupling reactions.…”