Fischer indole cyclization of phenylhydrazine and various ketones using carboxyl-functionalized ionic liquid, 1-carboxymethyl- 3-methylimidazolium tetrafluoroborate （abbreviated as [crnmim] [BF4]） as catalyst was su...Fischer indole cyclization of phenylhydrazine and various ketones using carboxyl-functionalized ionic liquid, 1-carboxymethyl- 3-methylimidazolium tetrafluoroborate （abbreviated as [crnmim] [BF4]） as catalyst was successfully performed. The yields of the target compounds were 80-92%, the purities were 96-98%. The catalyst could be recovered and reused for at least six times without significant loss in activity.展开更多
The activation of iron oxide Fischer–Tropsch Synthesis(FTS) catalysts was investigated during pretreatment: reduction in hydrogen followed by carburization in either CO or syngas mixture, or simultaneously reduction ...The activation of iron oxide Fischer–Tropsch Synthesis(FTS) catalysts was investigated during pretreatment: reduction in hydrogen followed by carburization in either CO or syngas mixture, or simultaneously reduction and carburization in syngas. A combination of different complementary in situ techniques was used to gain insight into the behavior of Fe-based FTS catalysts during activation. In situ XRD was used to identify the crystalline structures present during both reduction in hydrogen and carburization. An increase in reduction rate was established when increasing the temperature. A complete reduction was demonstrated in the ETEM and a grain size dependency was proven, i.e. bigger grains need higher temperature in order to reduce. XPS and XAS both indicate the formation of a small amount of carbonaceous species at the surface of the bulk metallic iron during carburization.展开更多
We used a chemical reduction method to synthesize the catalysts of cobalt(Co) and cobalt-ruthenium(Co-Ru) bifunctional supported on carbon nanotubes(CNTs) for Fischer–Tropsch synthesis(FTS) in a fixedbed reactor. The...We used a chemical reduction method to synthesize the catalysts of cobalt(Co) and cobalt-ruthenium(Co-Ru) bifunctional supported on carbon nanotubes(CNTs) for Fischer–Tropsch synthesis(FTS) in a fixedbed reactor. These Co-Ru/CNTs catalysts were synthesized with various weight proportions of Ru/Co(0.1 to 0.4 wt%) with keeping a fixed amount of cobalt(10 wt%). Moreover, for comparison purpose, CNTs supported Co-and Co(Ru)-based catalysts at same loading as the above catalysts were prepared through impregnation method. We characterize the present catalysts through the various techniques such as Energy–dispersive X-ray(EDX), Transmission Electron Microscopy(TEM), Brunauer–Emmett–Teller(BET),Hydrogen-Temperature-Programmed Reduction(H_2-TPR), Hydrogen-Temperature-Programmed Desorption(H_2-TPD) and O_2 titration. Thus using the chemical reduction method, a narrow particle size distribution was obtained so that the small cobalt particles were confined inside the CNTs. The Co-based catalyst prepared by impregnation was compared with the Co-Ru catalysts at the same loading. The results demonstrated that the use of chemical reduction method led to decrease the average Co oxide cluster size to8.7 nm so that the reduction enhanced about 24% and stabilized an earlier time at the stream. Among the prepared catalysts, the results indicated that the Co-Ru/CNTs catalysts demonstrated high catalytic activity with the highest long-chain hydrocarbons(C_(5+)), selectivity up to 74.76%, which was higher than those we obtained by the Co-Ru/γ-Al_2O_3(61._20%), Co/CNTs(43.68%) and Co/γ-Al_2O_3(37.69%). At the same time, comparing with those catalyst synthesized by impregnation, the use of chemical reduction led to enhancement of the C_(5+) selectivity from 59.30% to 68.83% and increment in FTS rate about 11% for the Co-Ru/CNTs catalyst.展开更多
In an attempt to synthesize an indole derivative,methyl 5-nitro-1H-indole-2-carb-oxylate,an isomeric change of methyl 2-[2-（4-nitrophenyl） hydrazono] propanoate from E to Z geometry was observed.The two isomers were...In an attempt to synthesize an indole derivative,methyl 5-nitro-1H-indole-2-carb-oxylate,an isomeric change of methyl 2-[2-（4-nitrophenyl） hydrazono] propanoate from E to Z geometry was observed.The two isomers were determined by single-crystal X-ray diffraction analysis.The Z isomer is stabilized in a six-membered ring conformation constructed by an intramolecular hydrogen bond.This isomeric change added a branched pathway in the mechanism of Fischer indole synthesis.展开更多
An efficient synthesis of 2, 3-disubstituted indole derivatives through low-valent titanium induced reductive cyclization of acylamido carbonyl compounds is described.
A synthesis of (2R,3aR,8aR)-6-chloro-3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid methyl ester (1) was achieved. An aldol reaction with Garner aldehyde, a hydroxyl introduction by Davis re-...A synthesis of (2R,3aR,8aR)-6-chloro-3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid methyl ester (1) was achieved. An aldol reaction with Garner aldehyde, a hydroxyl introduction by Davis re-agent, and a reductive intramolecular ring-closure reaction were served as the key steps. This piece of work pro-vides a new way to synthesize the analogues of hexahydropyrrolo[2,3-b]indole, starting from readily available chemical substrates and inexpensive reagents.展开更多
基金the Key Project of Shanghai Educational Committee(No.06ZZ82)
文摘Fischer indole cyclization of phenylhydrazine and various ketones using carboxyl-functionalized ionic liquid, 1-carboxymethyl- 3-methylimidazolium tetrafluoroborate （abbreviated as [crnmim] [BF4]） as catalyst was successfully performed. The yields of the target compounds were 80-92%, the purities were 96-98%. The catalyst could be recovered and reused for at least six times without significant loss in activity.
基金supported by the “Villum Center for the Science of Sustainable Fuels and Chemicals” (V-Sustain, grant number 9455) research initiative funded by the VILLUM FONDEN。
文摘The activation of iron oxide Fischer–Tropsch Synthesis(FTS) catalysts was investigated during pretreatment: reduction in hydrogen followed by carburization in either CO or syngas mixture, or simultaneously reduction and carburization in syngas. A combination of different complementary in situ techniques was used to gain insight into the behavior of Fe-based FTS catalysts during activation. In situ XRD was used to identify the crystalline structures present during both reduction in hydrogen and carburization. An increase in reduction rate was established when increasing the temperature. A complete reduction was demonstrated in the ETEM and a grain size dependency was proven, i.e. bigger grains need higher temperature in order to reduce. XPS and XAS both indicate the formation of a small amount of carbonaceous species at the surface of the bulk metallic iron during carburization.
文摘We used a chemical reduction method to synthesize the catalysts of cobalt(Co) and cobalt-ruthenium(Co-Ru) bifunctional supported on carbon nanotubes(CNTs) for Fischer–Tropsch synthesis(FTS) in a fixedbed reactor. These Co-Ru/CNTs catalysts were synthesized with various weight proportions of Ru/Co(0.1 to 0.4 wt%) with keeping a fixed amount of cobalt(10 wt%). Moreover, for comparison purpose, CNTs supported Co-and Co(Ru)-based catalysts at same loading as the above catalysts were prepared through impregnation method. We characterize the present catalysts through the various techniques such as Energy–dispersive X-ray(EDX), Transmission Electron Microscopy(TEM), Brunauer–Emmett–Teller(BET),Hydrogen-Temperature-Programmed Reduction(H_2-TPR), Hydrogen-Temperature-Programmed Desorption(H_2-TPD) and O_2 titration. Thus using the chemical reduction method, a narrow particle size distribution was obtained so that the small cobalt particles were confined inside the CNTs. The Co-based catalyst prepared by impregnation was compared with the Co-Ru catalysts at the same loading. The results demonstrated that the use of chemical reduction method led to decrease the average Co oxide cluster size to8.7 nm so that the reduction enhanced about 24% and stabilized an earlier time at the stream. Among the prepared catalysts, the results indicated that the Co-Ru/CNTs catalysts demonstrated high catalytic activity with the highest long-chain hydrocarbons(C_(5+)), selectivity up to 74.76%, which was higher than those we obtained by the Co-Ru/γ-Al_2O_3(61._20%), Co/CNTs(43.68%) and Co/γ-Al_2O_3(37.69%). At the same time, comparing with those catalyst synthesized by impregnation, the use of chemical reduction led to enhancement of the C_(5+) selectivity from 59.30% to 68.83% and increment in FTS rate about 11% for the Co-Ru/CNTs catalyst.
基金Supported by the Natural Science Foundation of Fujian Province (No. 2006 F5058)Fuzhou University (No. XRC-0527)
文摘In an attempt to synthesize an indole derivative,methyl 5-nitro-1H-indole-2-carb-oxylate,an isomeric change of methyl 2-[2-（4-nitrophenyl） hydrazono] propanoate from E to Z geometry was observed.The two isomers were determined by single-crystal X-ray diffraction analysis.The Z isomer is stabilized in a six-membered ring conformation constructed by an intramolecular hydrogen bond.This isomeric change added a branched pathway in the mechanism of Fischer indole synthesis.
文摘An efficient synthesis of 2, 3-disubstituted indole derivatives through low-valent titanium induced reductive cyclization of acylamido carbonyl compounds is described.
文摘A synthesis of (2R,3aR,8aR)-6-chloro-3a-hydroxy-1,2,3,3a,8,8a-hexahydropyrrolo[2,3-b]indole-2-carboxylic acid methyl ester (1) was achieved. An aldol reaction with Garner aldehyde, a hydroxyl introduction by Davis re-agent, and a reductive intramolecular ring-closure reaction were served as the key steps. This piece of work pro-vides a new way to synthesize the analogues of hexahydropyrrolo[2,3-b]indole, starting from readily available chemical substrates and inexpensive reagents.
