The molecular structures of indazole and 3-halogeno-indazole tautomers were calculated by the B3LYP method at the 6-311G^＊＊ level, both in the gaseous and aqueous phases, with full geometry optimization. The geometr...The molecular structures of indazole and 3-halogeno-indazole tautomers were calculated by the B3LYP method at the 6-311G^＊＊ level, both in the gaseous and aqueous phases, with full geometry optimization. The geometry and electronic structure of the tautomers of indazole, 3-halogeno-indazole and their transition states were obtained. The Onsager solvate theory model was employed for the aqueous solution calculations. The results of the calculation indicated that the N1-H form of the studied molecule is more stable than that of the N2-H form. The influences of the different 3-halogeno and solvent effects on the geometry, energy, charge and activation energy were discussed. The reaction mechanism of the tautomerization of indazole and 3-halogeno-indazole was also studied and a three-membered cyclic transition state of the tautomer reaction has been obtained.展开更多
The characteristic of coal spontaneous combustion includes oxidative property and exothermic capacity. It can really simulate the process of coal spontaneous combustion to use the large scale experimental unit loading...The characteristic of coal spontaneous combustion includes oxidative property and exothermic capacity. It can really simulate the process of coal spontaneous combustion to use the large scale experimental unit loading coal 1 000 kg. According to the field change of gas concentration and coal temperature determined through experiment of coal self ignite at low temperature stage, and on the basis of hydromechanics and heat transfer theory, some parameters can be calculated at different low temperature stage, such as, oxygen consumption rate, heat liberation intensity. It offers a theoretic criterion for quantitatively analyzing characteristic of coal self ignite and forecasting coal spontaneous combustion. According to coal exothermic capability and its thermal storage surroundings, thermal equilibrium is applied to deduce the computational method of limit parameter of coal self ignite. It offers a quantitative theoretic criterion for coal self ignite forecasting and preventing. According to the measurement and test of spontaneous combustion of Haibei coal, some token parameter of Haibei coal spontaneous combustion is quantitatively analyzed, such as, spontaneous combustion period of coal, critical temperature, oxygen consumption rate, heat liberation intensity, and limit parameter of coal self ignite.展开更多
In this paper kinetics of xylose dehydration into furfural using acetic acid as catalyst was studied comprehensively and systematically. The reaction order of both furfural and xylose dehydration was determined and th...In this paper kinetics of xylose dehydration into furfural using acetic acid as catalyst was studied comprehensively and systematically. The reaction order of both furfural and xylose dehydration was determined and the reaction activation energy was obtained by nonlinear regression. The effect of acetic acid concentration was also investi- gated. Reaction rate constants were gained. Reaction rate constant of xylose dehydration is kl = 4.189 × 10^10[A]^0.1676 axp （-108.5×1000/RT）, reaction rate constant of furfural degradation is k2=1.271×10^10[A]0.1375 exp （-63.413×1000/RT）and reaction rate constant of condensation reaction is k3-3.4051×10^10[A]0.1676 exp （-104.99×1000/RT）, Based on this, the kinetics equation of xylose dehydration into furfural in acetic acid was set up according to theory of Dunlop and Furfural generating rate equation is d[F]/dt=K1[x]0e-k1t-k2[F]-k3[X]0E-k1 1[F]展开更多
文摘The molecular structures of indazole and 3-halogeno-indazole tautomers were calculated by the B3LYP method at the 6-311G^＊＊ level, both in the gaseous and aqueous phases, with full geometry optimization. The geometry and electronic structure of the tautomers of indazole, 3-halogeno-indazole and their transition states were obtained. The Onsager solvate theory model was employed for the aqueous solution calculations. The results of the calculation indicated that the N1-H form of the studied molecule is more stable than that of the N2-H form. The influences of the different 3-halogeno and solvent effects on the geometry, energy, charge and activation energy were discussed. The reaction mechanism of the tautomerization of indazole and 3-halogeno-indazole was also studied and a three-membered cyclic transition state of the tautomer reaction has been obtained.
基金ThearticlesupportedfinanciallybyNationalNaturalScienceFoundationofChina (No .5 99740 2 0 )andSpecialFoundationofShaanxiEdu cationCommittee (No .99Jk2 2 0 )
文摘The characteristic of coal spontaneous combustion includes oxidative property and exothermic capacity. It can really simulate the process of coal spontaneous combustion to use the large scale experimental unit loading coal 1 000 kg. According to the field change of gas concentration and coal temperature determined through experiment of coal self ignite at low temperature stage, and on the basis of hydromechanics and heat transfer theory, some parameters can be calculated at different low temperature stage, such as, oxygen consumption rate, heat liberation intensity. It offers a theoretic criterion for quantitatively analyzing characteristic of coal self ignite and forecasting coal spontaneous combustion. According to coal exothermic capability and its thermal storage surroundings, thermal equilibrium is applied to deduce the computational method of limit parameter of coal self ignite. It offers a quantitative theoretic criterion for coal self ignite forecasting and preventing. According to the measurement and test of spontaneous combustion of Haibei coal, some token parameter of Haibei coal spontaneous combustion is quantitatively analyzed, such as, spontaneous combustion period of coal, critical temperature, oxygen consumption rate, heat liberation intensity, and limit parameter of coal self ignite.
文摘In this paper kinetics of xylose dehydration into furfural using acetic acid as catalyst was studied comprehensively and systematically. The reaction order of both furfural and xylose dehydration was determined and the reaction activation energy was obtained by nonlinear regression. The effect of acetic acid concentration was also investi- gated. Reaction rate constants were gained. Reaction rate constant of xylose dehydration is kl = 4.189 × 10^10[A]^0.1676 axp （-108.5×1000/RT）, reaction rate constant of furfural degradation is k2=1.271×10^10[A]0.1375 exp （-63.413×1000/RT）and reaction rate constant of condensation reaction is k3-3.4051×10^10[A]0.1676 exp （-104.99×1000/RT）, Based on this, the kinetics equation of xylose dehydration into furfural in acetic acid was set up according to theory of Dunlop and Furfural generating rate equation is d[F]/dt=K1[x]0e-k1t-k2[F]-k3[X]0E-k1 1[F]
