The reaction between chloranil and N-benzyldihydronicotinamide(BNAH)in borate buffer/DMF was investigated.The reaction mixture gave a strong esr signal,which is consistent with that of chloranil anion radical,and tetr...The reaction between chloranil and N-benzyldihydronicotinamide(BNAH)in borate buffer/DMF was investigated.The reaction mixture gave a strong esr signal,which is consistent with that of chloranil anion radical,and tetrachlorohydrophenol(QH_2)and N-benzylnicotinamide (BNA^+)were obtained as the sole products.When the reaction was run in benzene solution,a green coloured charge-transfer complex between the reactants could be isolated,which decomposed in polar solvents to give BNA-+ and QH_2.Based on kinetic studies by esr spectroscopy by the stopped-flow technique,a two-step electron-transfer mechanism for the reactionis proposed in contrast to the hydride-transfer mechanism reported in the literature.展开更多
The sol-gel process of citric acid chelating with metal cations for the synthesis of normal spinel LiMn 2O 4 and the reaction mechanism were investigated by means of XRD,IR,TG-DTA, and SEM.The results show that at t...The sol-gel process of citric acid chelating with metal cations for the synthesis of normal spinel LiMn 2O 4 and the reaction mechanism were investigated by means of XRD,IR,TG-DTA, and SEM.The results show that at the beginning lithium citrate and chelate compound of citric acid with manganese ions formed,and then with heating the esterification and condensation reactions occured between them and glycol.The products obtained are polymers in which metal cations are distributed homogeneously on atomic scale that ensure high reactivity to cations of Li + and Mn 2+.Firing the gel prepared by this process,the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are eliminated and avoided.At 400℃ phase-pure LiMn 2O 4 with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained.The model of chelate coordinate of double-molecule between citric acid and Mn 2+ in the gel network is proposed.It is important for explaining the dispersion state of Mn 2+ and the formation process of gel by this model.展开更多
文摘The reaction between chloranil and N-benzyldihydronicotinamide(BNAH)in borate buffer/DMF was investigated.The reaction mixture gave a strong esr signal,which is consistent with that of chloranil anion radical,and tetrachlorohydrophenol(QH_2)and N-benzylnicotinamide (BNA^+)were obtained as the sole products.When the reaction was run in benzene solution,a green coloured charge-transfer complex between the reactants could be isolated,which decomposed in polar solvents to give BNA-+ and QH_2.Based on kinetic studies by esr spectroscopy by the stopped-flow technique,a two-step electron-transfer mechanism for the reactionis proposed in contrast to the hydride-transfer mechanism reported in the literature.
基金theNationalNaturalScienceFoundationofChina (No .5 9972 0 2 7)theNaturalScienceFoundationofHubeiProvince (No .2 0 0 2AB0 74) )
文摘The sol-gel process of citric acid chelating with metal cations for the synthesis of normal spinel LiMn 2O 4 and the reaction mechanism were investigated by means of XRD,IR,TG-DTA, and SEM.The results show that at the beginning lithium citrate and chelate compound of citric acid with manganese ions formed,and then with heating the esterification and condensation reactions occured between them and glycol.The products obtained are polymers in which metal cations are distributed homogeneously on atomic scale that ensure high reactivity to cations of Li + and Mn 2+.Firing the gel prepared by this process,the lattice diffusions of solid reactant ions caused by non-homogeneity of reactants are eliminated and avoided.At 400℃ phase-pure LiMn 2O 4 with nanometer scale crystallization having precise stoichiometry and perfect crystallization can be obtained.The model of chelate coordinate of double-molecule between citric acid and Mn 2+ in the gel network is proposed.It is important for explaining the dispersion state of Mn 2+ and the formation process of gel by this model.
