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排序方式: 共有237条查询结果,搜索用时 31 毫秒
151.
Clément Lauzin N. Moazzen-Ahmadi A.R.W. McKellar 《Journal of Molecular Spectroscopy》2011,269(1):124-128
Infrared spectra of the weakly-bound T-shaped acetylene dimers DCCD–DCCD and DCCD–HCCH are studied in the region of the DCCD ν3 fundamental (∼2440 cm−1) using a pulsed supersonic slit-jet expansion and a tunable diode laser probe. The Ka = 0 ← 1 and 1 ← 0 subbands, corresponding to the vibration of the DCCD monomer at the “top” of the T, are analyzed. Compared to the analogous spectrum of HCCH–HCCH, the present results are much less perturbed. The tunneling splitting for (DCCD)2 in the excited state is determined to be 141 MHz, a big reduction from the previously determined ground state value of 424 MHz. The dimer A rotational constants show a large apparent increase upon vibrational excitation, and we discuss whether this increase is real. The linear DCCD–NN complex is also observed as an impurity in the spectrum, and it too is found to be unperturbed, in contrast with HCCH–NN. 相似文献
152.
Franco Cataldo 《Tetrahedron letters》2005,46(21):3665-3667
Polyynes solutions having as main components C6H2 and C8H2 can be prepared in hydrocarbon solvents by hydrolyzing calcium carbide in an NH4Cl aqueous solution containing Cu(I)/Cu(II) salts. The polyynes are released into a hydrocarbon solvent by acidification with concd. HCl. Heptane solutions with polyynes concentration as high as 0.1 M can be easily prepared. 相似文献
153.
V.I. Perevalov D. Jacquemart J.-L. Teffo V. Dana A. Valentin 《Journal of Molecular Spectroscopy》2003,218(2):180-189
The method of effective operators has been applied to the global fitting of line intensities of the acetylene molecule in the middle infrared. Simultaneous fittings of recently observed line intensities in the cold and hot bands lying in the 13.6, 7.8, and 5 μm regions have been performed. The eigenfunctions of the effective Hamiltonian developed for the global treatment of the vibration-rotation line positions of acetylene [O.M. Lyulin, V.I. Perevalov, S.A. Tashkun, J.-L. Teffo, in: Leonid N. Sinitsa (Ed.), 13th Symposium and School on High Resolution Molecular Spectroscopy, Proceedings of SPIE, vol. 4063, 2000, pp. 126-133] have been used in the calculations. The sets of effective dipole moment parameters obtained reproduce the observed line intensities within the experimental accuracy. The importance of l-type resonance, responsible for some large differences between intensities of the same lines in subbands having opposite parities, is exhibited and discussed. 相似文献
154.
A sensitive and rapid electrochemical method was developed for the determination of telmisartan based on the enhancement effect of sodium dodecyl benzene sulfonate (SDBS). In 0.1 mol L−1 HClO4 and in the presence of 7.5 × 10−5 mol L−1 SDBS, a well-defined and sensitive oxidation peak was observed for telmisartan at the acetylene black (AB) paste electrode. However, the oxidation peak is poor-shaped and the peak current is very low in the absence of SDBS, suggesting that SDBS shows obvious enhancement effect for the determination of telmisartan. After all the experimental parameters were optimized, a sensitive and simple electrochemical method was developed for determining telmisartan. The oxidation peak current is proportional to the concentration of telmisartan over the range from 2.5 × 10−7 to 2.0 × 10−5 mol L−1. The detection limit is 7.5 × 10−8 mol L−1 after 2 min of accumulation. This new voltammetric method was successfully used to detect telmisartan in drugs. 相似文献
155.
An efficient and simple procedure for the synthesis of ketene imines via a one‐pot three‐component reaction of cyclohexyl isocyanide, diethyl acetylenedicarboxylate, and 1,4‐dihydropyridines under ultrasonic irradiation is described. The remarkable advantages are the simplicity of the experimental procedures, high yields, and short reaction times. 相似文献
156.
157.
Manabu Sugimoto Ichiro Yamasaki Nobuteru Mizoe Masaharu Anzai Shigeyoshi Sakaki 《Theoretical chemistry accounts》1999,102(1-6):377-384
Acetylene insertion into Pt(II)–H and Pt(II)SiH3 bonds of PtH(SiH3)(PH3) was investigated using ab initio molecular orbital and M?ller-Plesset perturbation theory methods. The insertion into PtH
was predicted to proceed with a smaller activation energy (E
a
=12.8 kcal/mol) than that into PtSiH3 (E
a
=20.9 kcal/mol). The reaction energy (ΔE) of the insertion into PtH is 10 kcal/mol smaller than that for the insertion into PtSiH3, which reflects differences in bond energies between CH and CSi and between PtH and PtSiH3. A comparison with ethylene insertion revealed that the acetylene insertion occurs more easily, and the latter reaction is
more exothermic. A simple vibronic coupling model combined with Toyozawa's interaction mode analysis was used to examine interesting
differences in E
a
and ΔE between insertions into PtH and PtSiH3, and between acetylene and ethylene insertions. This analysis suggests that the factors determining E
a
are the stiffness of the PtH and PtSiH3 bonds and the vibronic coupling strength of acetylene and ethylene.
Received: 13 August 1998 / Accepted: 2 September 1998 / Published online: 15 February 1999 相似文献
158.
Nail M. Shavaleev 《Journal of organometallic chemistry》2007,692(4):921-925
A new acetylene ligand modified with the electron-accepting 1,4,5,8-naphthalenediimide group and its Pt(II) phosphine complexes are reported. The Pt(II) complexes incorporate optical properties of the imide group, and display two reversible imide-centred reduction processes. 相似文献
159.
Kinetics of the reaction between acetylene and phenylmagnesium bromide were investigated in diethyl ether in the presence of small additions of triethylamine and without a catalyst. The mechanistic scheme suggested by Grignard et al. was supplemented with the reaction of bromomagnesiumacetylene with the Grignard reagent. The rate constants for individual reactions were determined. Triethylamine catalyzes the reactions to different extents, the conversions of bromomagnesiumacetylene being the most susceptible to the catalysis. The possible ways of the action of the catalyst were discussed and the importance of nucleophilic assistance was stressed. 相似文献
160.
Efficient synthesis of deuterated 1,2,3-triazoles 总被引:1,自引:0,他引:1
Zsombor Gonda 《Tetrahedron letters》2010,51(48):6275-6277
A wide variety of 1-monosubstituted 1,2,3-triazoles were synthesized efficiently via a copper-catalyzed click-reaction between azides and acetylene gas, generated in situ from CaC2 with the addition of H2O or D2O. 相似文献