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排序方式: 共有238条查询结果,搜索用时 31 毫秒
1.
Reaction of acetylene dicarboxaldehyde monoacetal with substituted Meldrum’s acid leads good yields in 2-pyranones-4-carboxaldehydes substituted in position 3. 相似文献
2.
Using a high resolution Raman spectrometer, we have measured Ar-broadening coefficients in the ν2Q branch of C2H2 for 22 lines at 295 K, 20 lines at 174 K, and 16 lines at 134 K. These lines with J values ranging from 1 to 23 are located in the spectral range 1970.9-1974.3 cm−1. The collisional widths are obtained by fitting each spectral line with a Rautian profile. The resulting broadening coefficients are compared with theoretical values arising from close coupling and coupled states calculations. A satisfactory agreement is obtained at room as well as at low temperatures, especially for odd J lines. By comparing broadening coefficients at 295, 174, and 134 K from a simple power law, the temperature dependence of these broadenings has been determined both experimentally, and theoretically. 相似文献
3.
Bin Shao 《Tetrahedron letters》2005,46(19):3423-3427
A series of acetylenic pyrimidines was synthesized and subjected to microwave irradiation. In contrast to conventional heating, the microwave irradiations generally gave clean conversion to fused bicyclic pyridines for all substrates reported with shorter reaction time. This method has been successfully applied to the synthesis of both fused lactones and lactams. 相似文献
4.
测量反应体系压力变化的装置已有报道,但本文装置具有操作方便、记数准确等优点。 1 实 验 1.1 实验原理及试剂 详见文献。 1.2 装置及仪器 本文的无汞动力学测量装置用于乙炔氢氯化均相催化反应力学研究,其组装图如图1所示。 相似文献
5.
6.
The present paper covers the reaction ergodography for the addition of AlH3 to acetylene investigated by ab initio calculation with RHF/3-21G basis set. The changes in some physical properties along the reaction path (IRC) are presented. The formations of FMOs of the transition state have been analyzed according to the Fukui' s method. On the basis of the perturbation theory and Wolfsborg Helmholtz formula, we calculated the FMO' s energy orders of TS and its formation that shows the HOMO of TS consists of LUMO, HOMO of AlH3 and HOMO of HCCH. 相似文献
7.
8.
P. E. M. Siegbahn 《Theoretical chemistry accounts》1994,87(4-5):277-292
Summary The C-H activation reaction of acetylene by second row transition metal atoms has been studied including electron correlation of all valence electrons. Binding energies have been computed for both -coordinated complexes and C-H insertion products. It is found that for most atoms the -coordinated complexes are thermodynamically favoured, just as in the case for the corresponding ethylene reaction. The barrier height for the C-H insertion increases from acetylene to ethylene and to methane. This is in line with the experimental finding that there should be an inverse relation between C-H bond strengths and the difficulty to activate these bonds. To explain the detailed differences between the C-H activation of acetylene and ethylene, the interaction with two, rather than one, - and *-orbitals for acetylene is of key importance. The barrier height for the acetylene reaction increases significantly between niobium and molybdenum going to the right in the periodic table, just as for all oxidative addition reactions previously studied. The origin of this increase is that noibium has one empty 4d-orbital but for molybdenum all 4d-orbitals are occupied. Rhodium has the lowest barrier for C-H activation for all systems studied. 相似文献
9.
比较了铂,铑,钯的氯化物对乙炔和甲基二氯硅烷的气固相硅氢加成反应的催化活性;筛选了铂催化剂中的无机载体;研究了浸渍法和制备的铂催化剂的催化反应行为。结果表明,浸渍法制备的铂催化剂中存在两类稳定性不同的活性中心,铂离子是具有催化活性的组分,甲基二氯硅烷与铂离子间的氧化还原反应是导致催化剂 相似文献
10.
Boris A. Trofimov Lidiya N. Parshina Anatolii P. Tantsyrev Oksana V. Vysotskaya Nina K. Gusarova 《Tetrahedron》2007,63(47):11661-11665
Vinyl ethers, promising chiral carbohydrate synthons, have been synthesized by the addition of glucose acetals (1,2:5,6-di-O-isopropylidene-α-d-glucofuranose, methyl 4,6-O-benzylidene-α-d-glucopyranoside, 1,2-O-cyclohexylidene-α-d-glucofuranose, methyl α-d-glucopyranoside) to acetylene under atmospheric and elevated pressures in an autoclave in the presence of superbase catalytic systems (KOH-DMSO, t-BuOK-DMSO). The complete vinylation of 1,2:5,6-di-O-isopropylidene-α-d-glucofuranose and methyl α-d-glucopyranoside has been realized under elevated pressure of acetylene in the system KOH-THF as well. 相似文献