Introduction Organic compounds usually have labile bonds. It is well known that thousands of reactions are carried out in solutions, only a few in the gas-phase. Most chemists are now familiar with the fact that solve...Introduction Organic compounds usually have labile bonds. It is well known that thousands of reactions are carried out in solutions, only a few in the gas-phase. Most chemists are now familiar with the fact that solvent may have a strong influence on reaction rate and equilibrium, so in the last decade, resarching the influence of solvent effects on reaction rate and reaction equilibrium was a very important and展开更多
Substituent, temperature and solvent effects on tautomeric equilibria in several β-ketoamides have been investigated by means of nuclear magnetic resonance spectroscopy (NMR). Keto-enol equilibrium predominates over ...Substituent, temperature and solvent effects on tautomeric equilibria in several β-ketoamides have been investigated by means of nuclear magnetic resonance spectroscopy (NMR). Keto-enol equilibrium predominates over the amide-imidol one. The relative stability of the individual tautomers and the corresponding equilibrium shifts are explained considering electronic and steric effects and tautomer stabilization via internal hydrogen bonds. In solution, these compounds exist mainly as ketoamide and Z-enolamide tautomers, both presenting intramolecular hydrogen bonds.展开更多
Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated...Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated that the COF-TpPa with keto-enol tautomerism equilibrium structure shows excellent performance(yield>99%after 8 h)in the selective photocatalytic oxidative coupling of amines to imines under visible light irradiation.It is revealed that three kinds of reactive oxygen species(superoxide radical,hydroxyl radical and singlet oxygen)participate in this photocatalytic oxidation reaction.In addition,hydrogen protons cleaved from the benzyl are proven to be reduced to hydrogen in the conduction band of COF-TpPa in anaerobic atmosphere,accompanied with the formation of imines.The direct hydrogen evolution from amine provides an effective way to extract clean energy from organic molecule as well as the production of value-added chemicals.As a contrast,COF-LZU1 with similar structure and chemical composition to COF-TpPa but without keto-enol tautomerism exhibits worse optical properties and photocatalytic performance.It is also demonstrated that keto-enol tautomerism favors the adsorption of benzylamine based on the characterization results and theoretical calculations.展开更多
文摘Introduction Organic compounds usually have labile bonds. It is well known that thousands of reactions are carried out in solutions, only a few in the gas-phase. Most chemists are now familiar with the fact that solvent may have a strong influence on reaction rate and equilibrium, so in the last decade, resarching the influence of solvent effects on reaction rate and reaction equilibrium was a very important and
文摘Substituent, temperature and solvent effects on tautomeric equilibria in several β-ketoamides have been investigated by means of nuclear magnetic resonance spectroscopy (NMR). Keto-enol equilibrium predominates over the amide-imidol one. The relative stability of the individual tautomers and the corresponding equilibrium shifts are explained considering electronic and steric effects and tautomer stabilization via internal hydrogen bonds. In solution, these compounds exist mainly as ketoamide and Z-enolamide tautomers, both presenting intramolecular hydrogen bonds.
基金supported by the National Natural Science Foundation of China (51802015, 51972024)the Fundamental Research Funds for the Central Universities (FRF-TP-20-005A3)the Interdisciplinary Research Project for Young Teachers of USTB (Fundamental Research Funds for the Central Universities) (FRF-IDRY-19-020)。
文摘Photocatalytic oxidation of organic molecules into highly value-added products is an innovative and challenging research which has gradually attracted remarkable attention of scientists.In this work,it is demonstrated that the COF-TpPa with keto-enol tautomerism equilibrium structure shows excellent performance(yield>99%after 8 h)in the selective photocatalytic oxidative coupling of amines to imines under visible light irradiation.It is revealed that three kinds of reactive oxygen species(superoxide radical,hydroxyl radical and singlet oxygen)participate in this photocatalytic oxidation reaction.In addition,hydrogen protons cleaved from the benzyl are proven to be reduced to hydrogen in the conduction band of COF-TpPa in anaerobic atmosphere,accompanied with the formation of imines.The direct hydrogen evolution from amine provides an effective way to extract clean energy from organic molecule as well as the production of value-added chemicals.As a contrast,COF-LZU1 with similar structure and chemical composition to COF-TpPa but without keto-enol tautomerism exhibits worse optical properties and photocatalytic performance.It is also demonstrated that keto-enol tautomerism favors the adsorption of benzylamine based on the characterization results and theoretical calculations.
