The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.
The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The hi...The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 39.6% and 100% respectively at ambient temperature and pressure. The effects of structures of the bridge group R in the ligands on the dioxygen affinities and catalytic activities to epoxidize styrene were also investigated.展开更多
The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with c...The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with crowned bis-Schiff bases were measured and their Mn(III) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.展开更多
The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed...The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed to catalyze epoxidation of styrene. The effect of substituent R in a salicylidene of ML1~ML4 [ M = Co (II), Mn (III)Cl ] on the dioxygen affinities and biomimetic catalytic oxidation performance were also investigated. Among them, the MnL4Cl containing a pendant benzoaza crown ether ring showed highest conversion and selectiviy up to 54.9% and 96.9% respectively.展开更多
A range of ferrocenyl sulfides are synthesized and screened. Among them l-a-methysulphoferrocenyl ethyl acetate and l-a-methysulphoferrocenyl alcohol are found to be unexpected catalysts, which is first reported media...A range of ferrocenyl sulfides are synthesized and screened. Among them l-a-methysulphoferrocenyl ethyl acetate and l-a-methysulphoferrocenyl alcohol are found to be unexpected catalysts, which is first reported mediating in sulfur ylide epoxidation reactions, furnishing a novel approach for highly stereoselective synthesis of oxiranes with 98%-100% trans-isomer. The protocol also has excellent yield, convenient workup and recycled starting material. The reason of high trans-selectivity is due to the bulky ferrocenyl sulfide group, which stabilizes the intermediates and determines the trans priority. A possible catalytic mechanism is also proposed.展开更多
The model compounds of androgenic steroid-bismetalloporphyrins 3a—3d and androgenic monometalloporphyrins 2a—2d have been synthesized. Catalytic study in two-phase condition on epoxidation of styrene under the catal...The model compounds of androgenic steroid-bismetalloporphyrins 3a—3d and androgenic monometalloporphyrins 2a—2d have been synthesized. Catalytic study in two-phase condition on epoxidation of styrene under the catalysis of model catalysts shows that the catalytic performances of steroid-bismetalloporphyrin is superior to steroid-metalloporphyrin and the corresponding simple metalloporphyrin. The excellent catalytic property of steriod-bismetalloporphyrin can be rationalized as the hydrophobic action of steroid framework and the cooperative action of two metalloporphyrins in catalysis.展开更多
文摘The dioxygen affinities and catalytic epoxidation performance of transition-metal hydroxamates were investigated for the first time. The effects of substituents on these properties were also discussed in the paper.
文摘The oxygenation constants of transition-metal complexes with benzoin Schiff bases were measured and these complexes were first employed as models for mimicking monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 39.6% and 100% respectively at ambient temperature and pressure. The effects of structures of the bridge group R in the ligands on the dioxygen affinities and catalytic activities to epoxidize styrene were also investigated.
基金the National Natural Science Foundation of China.
文摘The dioxygen affinities and biomimetic catalytic performance of transition-metal complexes with (15-crown-5) salophen and its substituted derivatives Mere examined. The oxygenation constants of Co(II) complexes with crowned bis-Schiff bases were measured and their Mn(III) complexes were employed as models to mimic monooxygenase in catalytic epoxidation of styrene. The highest conversion and selectivity were up to 57.2% and 100% respectively at ambient temperature and pressure. The effects of crown ether ring and substituents R on the dioxygen affinities and catalytic activities were also investigated through comparing with the uncrowned analogues.
文摘The oxygenation constants and thermodynamic parameter (ΔHo, ΔSo) of Co (II) complexes with unsymmetrical bis-Schiff baeses were measured and their Mn(III) complexes as models of mimicking monooxygenase were employed to catalyze epoxidation of styrene. The effect of substituent R in a salicylidene of ML1~ML4 [ M = Co (II), Mn (III)Cl ] on the dioxygen affinities and biomimetic catalytic oxidation performance were also investigated. Among them, the MnL4Cl containing a pendant benzoaza crown ether ring showed highest conversion and selectiviy up to 54.9% and 96.9% respectively.
基金Project supported by the National Natural Science Foundation of China (No. 29972036) and the Postdoctoral Science Foundation of China (No. 2003033537)
文摘A range of ferrocenyl sulfides are synthesized and screened. Among them l-a-methysulphoferrocenyl ethyl acetate and l-a-methysulphoferrocenyl alcohol are found to be unexpected catalysts, which is first reported mediating in sulfur ylide epoxidation reactions, furnishing a novel approach for highly stereoselective synthesis of oxiranes with 98%-100% trans-isomer. The protocol also has excellent yield, convenient workup and recycled starting material. The reason of high trans-selectivity is due to the bulky ferrocenyl sulfide group, which stabilizes the intermediates and determines the trans priority. A possible catalytic mechanism is also proposed.
基金Project (No. 29572060) supported by the National Natural Science Foundation of China.
文摘The model compounds of androgenic steroid-bismetalloporphyrins 3a—3d and androgenic monometalloporphyrins 2a—2d have been synthesized. Catalytic study in two-phase condition on epoxidation of styrene under the catalysis of model catalysts shows that the catalytic performances of steroid-bismetalloporphyrin is superior to steroid-metalloporphyrin and the corresponding simple metalloporphyrin. The excellent catalytic property of steriod-bismetalloporphyrin can be rationalized as the hydrophobic action of steroid framework and the cooperative action of two metalloporphyrins in catalysis.
