The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and...The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and the synthesis of drugs.Nowadays,high-fructose corn syrup(HFCS)is industrially produced in more than 10 million tons annually using immobilized glucose isomerase.Some low-calorie saccharides such as tagatose and psicose,which are becoming popular sweeteners,have also been produced on a pilot scale in order to replace sucrose and HFCS.However,current catalysts and catalytic processes are still difficult to utilize in biomass conversion and also have strong substrate dependence in producing high-value,rare sugars.Considering the specific reaction properties of saccharides and catalysts,since the pioneering discovery by Fischer,various catalysts and catalytic systems have been discovered or developed in attempts to extend the reaction pathways,improve the reaction efficiency,and to potentially produce commercial products.In this review,we trace the history of sugar isomerization/epimerization reactions and summarize the important breakthroughs for each reaction as well as the difficulties that remain unresolved to date.展开更多
Compound 2 with 14β-hydroxyl group was successfully converted into its epimerized α-counterpart via oxidation - reduction.The elimination product (6) was auto-oxidized to epoxide 8,even in the solid state
: The microbiological transformaion of a natural taxoid 10-deacetylbaccatin III into its C-7 epimer, 10-deacetylbaccatin V with Microsphaeropsis onychiuri, a fungus isolated from the inner bark of Taxus yunnanensis is...: The microbiological transformaion of a natural taxoid 10-deacetylbaccatin III into its C-7 epimer, 10-deacetylbaccatin V with Microsphaeropsis onychiuri, a fungus isolated from the inner bark of Taxus yunnanensis is described.展开更多
In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photo...In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photoresponsive beha-vior of the green, environment friendly product was investigated. The end hydroxyl group of lignin was modified with the chromophoric systems by DCC coupling. The chromophoric systems as well as the chromophore-bound biopolymer core systems were purified by column chromatography. The products were characterized by UV-visible, fluorescence, FT-IR and NMR spectroscopic methods. The results of the studies show that incorporation of the chromophoric system on to the lignin core enhanced the light absorption, emission and light stabilization properties of the chromophoric system. The light fastening properties of chromophoric system and the modified product were compared. It shows that stability of the chromophoric system greatly enhanced on attaching to the polymeric system. The trans-cis photoisomerisation and the reverse cis-trans thermal conversions were also assisted by the lignin core. The remarkable stability on irradiation shows that this is a novel photoresponsive system with excellent light fastening properties which would find application in coating materials, dyes, paints, inks, therapeutic agents and many more.展开更多
The natural product, neoclausenamide was synthesized through the 'biomimetic' route and the stereoselective reduction of the ketone group wherein were described.
The Irvingia gabonensis kernels, which have been extensively studied for their numerous virtues, including the ability to act against the accumulation of fats in the body[1], contain an oil. The aging of this oil unde...The Irvingia gabonensis kernels, which have been extensively studied for their numerous virtues, including the ability to act against the accumulation of fats in the body[1], contain an oil. The aging of this oil under two different conditions of conservation was the subject of our work. One of the results was an increase in the content of long-chain carbonaceous fatty acids during aging for 11 months of storage at low temperature (6℃) and at 30℃. This behavior does not find a concordant explanation by the comparative analysis of the chemical indices. Hence, there is the need to use the Medium Infra-Red spectroscopy (MIR) which allowed to clarify the information of the saponification index, to justify the weakness of the formation of peroxides in the case of the conservation at 30℃ and to confirm the information given by the peroxide index. It also allowed to understand the formation of the long carbon chains by the “cis-trans” isomerization and the homolytic cuts which intervene within the matrix of the fat by the analysis of the number of -CH<sub>2</sub> and -CH<sub>3</sub> groups in the two conditions of conservation. This study reveals that the rapid solidification of Irvingia gabonensis oil at room temperature[2] is an advantage for its preservation at room temperature but a great weakness when the fat is stored at low temperature.展开更多
基金Financial support by Dual Initiative Project of Jiangsu Province and Changzhou University is gratefully acknowledgedSample analysis supported by Analysis and Testing Center,NERC Biomass of Changzhou University was also greatly acknowledged.
文摘The transformation of aldose to ketose or common sugars into rare saccharides,including rare ketoses and aldoses,is of great value and interest to the food industry and for saccharidic biomass utilization,medicine,and the synthesis of drugs.Nowadays,high-fructose corn syrup(HFCS)is industrially produced in more than 10 million tons annually using immobilized glucose isomerase.Some low-calorie saccharides such as tagatose and psicose,which are becoming popular sweeteners,have also been produced on a pilot scale in order to replace sucrose and HFCS.However,current catalysts and catalytic processes are still difficult to utilize in biomass conversion and also have strong substrate dependence in producing high-value,rare sugars.Considering the specific reaction properties of saccharides and catalysts,since the pioneering discovery by Fischer,various catalysts and catalytic systems have been discovered or developed in attempts to extend the reaction pathways,improve the reaction efficiency,and to potentially produce commercial products.In this review,we trace the history of sugar isomerization/epimerization reactions and summarize the important breakthroughs for each reaction as well as the difficulties that remain unresolved to date.
文摘Compound 2 with 14β-hydroxyl group was successfully converted into its epimerized α-counterpart via oxidation - reduction.The elimination product (6) was auto-oxidized to epoxide 8,even in the solid state
文摘: The microbiological transformaion of a natural taxoid 10-deacetylbaccatin III into its C-7 epimer, 10-deacetylbaccatin V with Microsphaeropsis onychiuri, a fungus isolated from the inner bark of Taxus yunnanensis is described.
文摘In the present study, a photoresponsive chromophoric system such as 4-[(E)-2-(3-hydro xynaphthalen-2-yl)diazen-1-yl] benzoic acid was incorporated on to lignin core by functional transformation reactions and the photoresponsive beha-vior of the green, environment friendly product was investigated. The end hydroxyl group of lignin was modified with the chromophoric systems by DCC coupling. The chromophoric systems as well as the chromophore-bound biopolymer core systems were purified by column chromatography. The products were characterized by UV-visible, fluorescence, FT-IR and NMR spectroscopic methods. The results of the studies show that incorporation of the chromophoric system on to the lignin core enhanced the light absorption, emission and light stabilization properties of the chromophoric system. The light fastening properties of chromophoric system and the modified product were compared. It shows that stability of the chromophoric system greatly enhanced on attaching to the polymeric system. The trans-cis photoisomerisation and the reverse cis-trans thermal conversions were also assisted by the lignin core. The remarkable stability on irradiation shows that this is a novel photoresponsive system with excellent light fastening properties which would find application in coating materials, dyes, paints, inks, therapeutic agents and many more.
文摘The natural product, neoclausenamide was synthesized through the 'biomimetic' route and the stereoselective reduction of the ketone group wherein were described.
文摘The Irvingia gabonensis kernels, which have been extensively studied for their numerous virtues, including the ability to act against the accumulation of fats in the body[1], contain an oil. The aging of this oil under two different conditions of conservation was the subject of our work. One of the results was an increase in the content of long-chain carbonaceous fatty acids during aging for 11 months of storage at low temperature (6℃) and at 30℃. This behavior does not find a concordant explanation by the comparative analysis of the chemical indices. Hence, there is the need to use the Medium Infra-Red spectroscopy (MIR) which allowed to clarify the information of the saponification index, to justify the weakness of the formation of peroxides in the case of the conservation at 30℃ and to confirm the information given by the peroxide index. It also allowed to understand the formation of the long carbon chains by the “cis-trans” isomerization and the homolytic cuts which intervene within the matrix of the fat by the analysis of the number of -CH<sub>2</sub> and -CH<sub>3</sub> groups in the two conditions of conservation. This study reveals that the rapid solidification of Irvingia gabonensis oil at room temperature[2] is an advantage for its preservation at room temperature but a great weakness when the fat is stored at low temperature.
