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981.
CrO3.CH3NH2.HCl/Al2O3的制备及其对苯偶姻体系的氧化反应 总被引:1,自引:0,他引:1
CrO3·CH3NH2·HCl/Al2O3的制备及其对苯偶姻体系的氧化反应张贵生*石启增陈密峰蔡昆(河南师范大学化学系新乡453002)关键词CrO3·CH3NH2·HCl/Al2O3,苯偶姻,苯偶酰,氧化1996-08-18收稿,1996-11-0... 相似文献
982.
Marie-Paule Pileni 《Chemical physics letters》1980,75(3):540-544
Photoinduced electron transfer from Zn tetraphenylporphyrin to acceptors solubilized either in the lipid interior or aqueous bulk of anionic oil-in-water microemulsions has been investigated by nanosecond laser photolysis. While intimate cosolubilization appears to decrease the efficiency of electron transfer in the former, enhanced charge separation of the redox products has been observed in the latter. 相似文献
983.
Spectral quantities of cyclopropane, cyclobutane, cyclohexane, and of several derivatives, have been calculated by a semiempirical all-valence electron SCF-CI MO method. In cyclopropane, HOMO is practically localized in the carbon-frame, and LVMO is purely so. In cyclobutane, these two MO's are based on C-H bonds, while cyclohexane holds an intermediate position. Despite the overall similarity-experimental and computed-of the spectra of these molecules, assignments are non-parallel. Like cyclopropane, cyclobutane can extend conjugation, but to a diminished degree; cyclohexane behaves in this respect like an acyclic alkane. An interpretation of this gradation, in terms of the nature of high-lying MO's, is proposed. 相似文献
984.
Conformations of 2-methoxytetrahydropyran as a model for the six-membered ring in aldopyranosides have been calculated by the PCILO method using the algorithm of the conjugated gradient to optimize the geometry. The calculated geometry of the fourteen basic forms of 2-methoxytetrahydropyran was found to be in agreement with the available data obtained by X-ray diffraction of pyranosides. The results indicate differences in the geometry of 2-methoxytetrahydropyran resulting from the change of the axial vs. equatorial position of the methoxyl group. These changes are particularly meaningful in the values of bond angles and they are in agreement with the anomeric and exoanomeric effects. The experimentally found differences in the energies of an axial (4
C
1) and equatorial (1
C
4) conformer, G = 2.9–3.7 kJ/mol, and the dipole moment, = 1.20 ± 0.05 D (1D = 3.33 10–30mAs) agree well with the calculated values E = 3.18 kJ/mol and <> = 1.18 D which, in turn, suggest that the axial conformer is preferred over the equatorial one by a ratio a:e = 78:22. 相似文献
985.
G. G. Danagulyan D. A. Tadevosyan F. S. Kinoyan 《Chemistry of Heterocyclic Compounds》2006,42(6):782-787
Intermediate recyclization products were obtained in a study of the Kost-Sagitullin rearrangement of a series of 1,2-dialkylpyrimidinium
iodides. The initial attack of the nucleophile leads to the formation of products of the addition of the hydroxyl group, namely,
the corresponding pseudo bases. Heating one of these intermediates in ethanol or in the presence of primary amines leads to
rearrangement to give a pyridone derivative. Upon heating in chloroform, the pseudo bases readily lose a water molecule and
are converted to anhydro bases, namely, derivatives of 1-alkyl-1,2-dihydro-2-methylidenepyrimidine.
__________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 894–900, May, 2006. 相似文献
986.
This review covers our extensive research activities in the area of fluorine containing phospha- and arsaalkenes as well as selenocarbonyls, which differ considerably in their properties and reactivities from their alkyl and aryl counterparts and thus contribute in a gratifying manner to the still growing field of unsaturated element-carbon compounds of 3rd and 4th row main group elements E. Of particular interest is the influence of the fluorine substituents and other small groups (OR, NR2) with either inductive and/or mesomeric effects on the polarity and reactivity of the EC bond. Addition reactions of proton acidic and hydridic polar HX reactants as well as [2+2], [3+2] and [4+2] cycloadditions have been thoroughly studied. The results obtained allow a classification of the EC systems within five different types, A to E, and prove a change from “normal” to “inverse” heteroalkenes in this sequence. The ligand properties of some derivatives have also been investigated in some detail. 相似文献
987.
988.
Ti2(OMe)4/SiO2催化剂的制备及其合成碳酸二甲酯的反应性能 总被引:4,自引:2,他引:4
采用表面改性和离子交换法制备了SiO2负载的Ti2(OMe)4双核桥联配合物催化剂,用IR、TPD和微反技术考察了催化剂的表面构造及CO2和CH3OH在催化剂表面上的化学吸附和反应性能。结果表明:双核桥联配合物Ti2(OMe)4以Ti-O-Si键锚定在SiO2表面上;CO2在催化剂表面存在桥式和甲氧碳酸酯基两种吸附态,其中甲氧碳酸酯基吸附态是生成DMC的关键物种;CH3OH在催化剂上只有一种分子吸附态。在150℃以下,CO2和CH3OH在Ti2(OMe)4/SiO2催化剂表面上高选择地生成碳酸二甲酯。 相似文献
989.
CHEN Shuixia LIU Jinrong ZHANG Xiaoping ZENG Hanmin Materials Science Institute Zhongshan University Guangzhou Department of Environmental Science Engineering South China University of Technology Guangzhou P. R. China 《Chinese Journal of Reactive Polymers》2002,(2)
1. INTRODUCTION Microbial pollution will bring about various problems in industry and other vital fields, such as causing decomposing of materials, harming people抯 health. In order to reduce these problems, new antibacterial materials have been demanded. Recently, much attention has been paid to inorganic materials including zinc oxide [1~4]. These inorganic antibacterial materials are now substituting for organic materials to avoid releasing noxious organic molecules harmful to humans;… 相似文献
990.
A. S. Golubev N. D. Chkanikov M. Yu. Antipin Yu. T. Struchkov A. F. Kolomiets A. V. Fokin 《Russian Chemical Bulletin》1992,41(8):1425-1429
Condensation of methyl trifluoropyruvate with 2-(3,4-dimethoxyphenyl)ethylamine, tryptamine, and (D, L)-tryptophan yielded 1-methoxycarbonyl-1-trifluoromethyl-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline, 1-methoxycarbonyl-1-trifluoromethyl-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole, and Z-1-methoxycarbonyl-1-trifluoromethyl-3-carboxy-1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indole, respectively. The Z configuration of the latter was determined by x-ray structural analysis.A. N. Nesmayanov Institute of Organoelemental Compounds, Russian Academy of Sciences, 117813 Moscow, Russia. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1831–1836, August, 1992. 相似文献