Organic electrosynthesis has been widely used as an environmentally conscious alternative to conventional methods for redox reactions because it utilizes electric current as a traceless redox agent instead of chemical...Organic electrosynthesis has been widely used as an environmentally conscious alternative to conventional methods for redox reactions because it utilizes electric current as a traceless redox agent instead of chemical redox agents. Indirect electrolysis employing a redox catalyst has received tremendous attention, since it provides various advantages compared to direct electrolysis. With indirect electrolysis, overpotential of electron transfer can be avoided, which is inherently milder, thus wide functional group tolerance can be achieved. Additionally, chemoselectivity, regioselectivity, and stereoselectivity can be tuned by the redox catalysts used in indirect electrolysis. Furthermore, electrode passivation can be avoided by preventing the formation of polymer films on the electrode surface. Common redox catalysts include N-oxyl radicals, hypervalent iodine species, halides, amines, benzoquinones(such as DDQ and tetrachlorobenzoquinone), and transition metals. In recent years, great progress has been made in the field of indirect organic electrosynthesis using transition metals as redox catalysts for reaction classes including C–H functionalization, radical cyclization, and cross-coupling of aryl halides-each owing to the diverse reactivity and accessible oxidation states of transition metals. Although various reviews of organic electrosynthesis are available, there is a lack of articles that focus on recent research progress in the area of indirect electrolysis using transition metals, which is the impetus for this review.展开更多
Visible light promoted difunctionalization of alkynes is reviewed. The difunctionalization reaction is achieved by different reagents. Radicals such as carbon(sp3), carbon(sp2), and other heteroatom(P, S, N, Se, O, an...Visible light promoted difunctionalization of alkynes is reviewed. The difunctionalization reaction is achieved by different reagents. Radicals such as carbon(sp3), carbon(sp2), and other heteroatom(P, S, N, Se, O, and halide) radicals initiated by visible light can undergo radical addition to a carbon-carbon triple bond. Upon further transformation, the desired difunctionalized products are obtained. Some organometallic complexes can be activated by visible light;the difunctionalization of alkynes is catalyzed by these species. Other reagents like 1,3-dipole precursors could also react with alkynes to give difunctionalization products;here, the 1,3-dipole derivatives are obtained by visible light photocatalysis. So far, the strategy has been succeeded in the formation of C–C bonds and C–X bonds. Several valuable chemical skeletons have been constructed under mild conditions. However, high regio-and stereoselectivities in some direct difunctionalization methodologies are yet to be achieved.展开更多
Solar‐driven thermochemical water splitting represents one efficient route to the generation of H2as a clean and renewable fuel.Due to their outstanding catalytic abilities and promising solar fuel production capacit...Solar‐driven thermochemical water splitting represents one efficient route to the generation of H2as a clean and renewable fuel.Due to their outstanding catalytic abilities and promising solar fuel production capacities,perovskite‐type redox catalysts have attracted significant attention in this regard.In the present study,the perovskite series La1‐xCaxMn1‐yAlyO3(x,y=0.2,0.4,0.6,or0.8)was fabricated using a modified Pechini method and comprehensively investigated to determine the applicability of these materials to solar H2production via two‐step thermochemical water splitting.The thermochemical redox behaviors of these perovskites were optimized by doping at either the A(Ca)or B(Al)sites over a broad range of substitution values,from0.2to0.8.Through this doping,a highly efficient perovskite(La0.6Ca0.4Mn0.6Al0.4O3)was developed,which yielded a remarkable H2production rate of429μmol/g during two‐step thermochemical H2O splitting,going between1400and1000°C.Moreover,the performance of the optimized perovskite was found to be eight times higher than that of the benchmark catalyst CeO2under the same experimental conditions.Furthermore,these perovskites also showed impressive catalytic stability during two‐step thermochemical cycling tests.These newly developed La1‐xCaxMn1‐yAlyO3redox catalysts appear to have great potential for future practical applications in thermochemical solar fuel production.展开更多
基金supported by the National Natural Science Foundation of China (21821002, 21772222, and 91956112)Chinese Academy of Sciences (XDB20000000)Science and Technology Commission of Shanghai Municipality (18JC1415600 and 20JC1417100)。
文摘Organic electrosynthesis has been widely used as an environmentally conscious alternative to conventional methods for redox reactions because it utilizes electric current as a traceless redox agent instead of chemical redox agents. Indirect electrolysis employing a redox catalyst has received tremendous attention, since it provides various advantages compared to direct electrolysis. With indirect electrolysis, overpotential of electron transfer can be avoided, which is inherently milder, thus wide functional group tolerance can be achieved. Additionally, chemoselectivity, regioselectivity, and stereoselectivity can be tuned by the redox catalysts used in indirect electrolysis. Furthermore, electrode passivation can be avoided by preventing the formation of polymer films on the electrode surface. Common redox catalysts include N-oxyl radicals, hypervalent iodine species, halides, amines, benzoquinones(such as DDQ and tetrachlorobenzoquinone), and transition metals. In recent years, great progress has been made in the field of indirect organic electrosynthesis using transition metals as redox catalysts for reaction classes including C–H functionalization, radical cyclization, and cross-coupling of aryl halides-each owing to the diverse reactivity and accessible oxidation states of transition metals. Although various reviews of organic electrosynthesis are available, there is a lack of articles that focus on recent research progress in the area of indirect electrolysis using transition metals, which is the impetus for this review.
基金supported by Zhejiang Provincial Natural Science Foundation of China(LR19B020001)the National Natural Science Foundation of China(21472162,21772171)the National Basic Research Program of China(2015CB856600)~~
文摘Visible light promoted difunctionalization of alkynes is reviewed. The difunctionalization reaction is achieved by different reagents. Radicals such as carbon(sp3), carbon(sp2), and other heteroatom(P, S, N, Se, O, and halide) radicals initiated by visible light can undergo radical addition to a carbon-carbon triple bond. Upon further transformation, the desired difunctionalized products are obtained. Some organometallic complexes can be activated by visible light;the difunctionalization of alkynes is catalyzed by these species. Other reagents like 1,3-dipole precursors could also react with alkynes to give difunctionalization products;here, the 1,3-dipole derivatives are obtained by visible light photocatalysis. So far, the strategy has been succeeded in the formation of C–C bonds and C–X bonds. Several valuable chemical skeletons have been constructed under mild conditions. However, high regio-and stereoselectivities in some direct difunctionalization methodologies are yet to be achieved.
基金supported by the Australian Research Council(FT120100913)the National Natural Science Foundation of China(51372248,51432009)~~
文摘Solar‐driven thermochemical water splitting represents one efficient route to the generation of H2as a clean and renewable fuel.Due to their outstanding catalytic abilities and promising solar fuel production capacities,perovskite‐type redox catalysts have attracted significant attention in this regard.In the present study,the perovskite series La1‐xCaxMn1‐yAlyO3(x,y=0.2,0.4,0.6,or0.8)was fabricated using a modified Pechini method and comprehensively investigated to determine the applicability of these materials to solar H2production via two‐step thermochemical water splitting.The thermochemical redox behaviors of these perovskites were optimized by doping at either the A(Ca)or B(Al)sites over a broad range of substitution values,from0.2to0.8.Through this doping,a highly efficient perovskite(La0.6Ca0.4Mn0.6Al0.4O3)was developed,which yielded a remarkable H2production rate of429μmol/g during two‐step thermochemical H2O splitting,going between1400and1000°C.Moreover,the performance of the optimized perovskite was found to be eight times higher than that of the benchmark catalyst CeO2under the same experimental conditions.Furthermore,these perovskites also showed impressive catalytic stability during two‐step thermochemical cycling tests.These newly developed La1‐xCaxMn1‐yAlyO3redox catalysts appear to have great potential for future practical applications in thermochemical solar fuel production.
