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51.
Sz. Vass 《Chemical physics letters》1980,70(1):135-137
The small number of reagents solubilized in a micelle prohibits the use of conventional reaction kinetics. In order to describe the kinetics of the reaction A + B ? AB proceeding in a micellar phase, a stochastic model is evaluated. The deviation of these results from those obtained by conventional kinetics may be as high as 20%. 相似文献
52.
Analysis of the NMR spectra of 1,2,3-trichloropropane and 1,2,3-tribromopropane in various media shows the most stable conformer to be AG-. The populations of several conformera have been estimated by using pure trans and gauche coupling constants obtained from closely similar molecules. The calculated populations found in non-polar solvents agree well with those obtained by electron diffraction studies in the gas phase. It is suggested that the AG- form is stabilised relative to AG+ by the former having two parallel (1:3) halogen-hydrogen attractions against one in the AG+ form. Comparison is made to related molecules where the most stable conformers also have the greatest number of parallel (1:3) halogen-hydrogen interactions. 相似文献
53.
Titrimetric determinations of arenediazonium salts can be based on ion-pair formation between the diazonium cation and tetraphenylborate. Titrations are done under cooling with ice and are followed potentiometrically with organic ion-selective electrodes comprising PVC membranes plasticized with polar solvents and coated on aluminium wires. The method was tested in determinations of arenediazonium salts derived from 20 aromatic amines, including aniline, toluidines, naphthylamines and their derivatives. Except for compounds containing hydrophylic groups such as —COOH and —OH, the potentiometric titration curves have well defined end-points. The results are reproducible, with relative standard deviations in the range 0.4–1.4% at the millimolar level. The method can be used for reliable determinations of arenediazonium salts in analytical control of azo dyestuff production. 相似文献
54.
Vikram S. Kushawaha 《Chemical physics letters》1980,72(3):451-454
A laser-induced chemical reaction of I2 + C2H2 has been studied and the formation of cis and tians isomers of 1,2-diiodoethylene has been observed. The ratio of the two isomers of 1,2-diodoethylene changes markedly upon changing the laser wavelengths of excitation of the I2 molecule 相似文献
55.
Aromatic hydrocarbons provide nucleation centers for the formation of clusters of inert gases in high-flow supersonic beams. Large clusters of Ar, each containing a single tetracene (T) molecule, were prepared by supersonic expansion of the seeded gas at pressures p = 3000–13000 Torr and interrogated by laser-induced fluorescence spectroscopy Evidence is reported for homogeneous line broadening of large TArn clusters prepared at p? 8000 Torr. 相似文献
56.
Chlorosulfonyl isocyanate adds to α-pinene in concerted fashion to give the unrearranged N-chlorosulfonyl-β-lactam 2 (75%). Thermolysis of cycloadduct 2 affords the rearranged N-chlorosulfonyl-γ-lactam 6 (60%) via a sequence of transient carbonium ions (45). Reductive hydrolysis of 2 and 6 gave, respectively, the NH-β-lactam 3 (70%) and the NH-γ-lactam 7 (70%). Proof of structure of the rearranged γ-lactams 6 and 7 are provided, respectively, by X-ray crystallographic analysis and the application of the Eu(dpm)3 NMR shift reagent. 相似文献
57.
Thi Thanh-Tâm Nguyên Claude Delseth Jean-Pierre Kintzinger Pierre-Alain Carrupt Pierre Vogel 《Tetrahedron》1980,36(19):2793-2797
Natural-abundance 17O-NMR spectra of 7-oxanorbornane exo-3-oxatricyclo [3.2.1.02.4]octane and their unsaturated derivatives (endo cyclic and exocyclic double bonds) have been measured. Linear correlation laws were observed for of these ethers/corresponding hydrocarbons. The “cyclization shifts” for δo in ethers were not correlated by the “cyclization shifts” for δc of the corresponding hydrocarbons. 相似文献
58.
The determination of nickel in various silicate rocks and glasses by photon activation analysis with a linear electron accelerator is described. Simultaneous irradiation of the sample and comparative standards produces the 58Ni(γ, n)57Ni reaction, and a post-irradiation chemical separation is used in conjunction with Ge(Li) γ-spectrometry. Nickel abundances for ten standard silicate rocks and two elementally doped glasses are presented and compared with the data previously published. The method is quite simple and gives good reproducible results for nickel down to sub-p.p.m. levels. 相似文献
59.
Components, of the magnetizability tensor for the B1Σ+u and a 3Σ+g states ot the hydrogen molecule have been calculated for fixed bond lengths near equilibrium. Explicitly correlated “generalised James-Coolidge” type wavefunctions were used. It is found thilt in the B 1Σ+u state the molecular magnetizability is a positive quantity. 相似文献
60.
Bromoacetyl chloride and bromoacetyl bromide are studied by gas phase electron diffraction at nozzle-tip temperatures of 70°C and 77°C, respectively. Both compounds exist as mixtures of anti and gauche conformers. The mole fraction anti, with uncertainties estimated at 2σ, was found to be 0.474(0.080) for bromoacetyl chloride and 0.615(0.069) for bromoacetyl bromide. The results for the distance (ra)and angle (∠α) parameters, with parenthesized uncertainties of 2σ including estimated uncertainty in the electron wave length and correlation effects are as follows: (1) bromoacetyl chloride, r(C-H) = 1.086(0.062) Å, r(CO) = 1.188(0.009) Å, r(C-C) = 1.519(0.018) Å, r(C-Cl) = 1.789(0.011) Å, r(C-Br) = 1.935(0.012) Å, ∠C-CO = 127.6(1.3)°, ∠C-C-Cl = 111.3(1.1)°, ∠C-C-Br = 111.0(1.5)°, ∠H-C-H = 109.5°(assumed), /o (gauche torsion angle relative to 0° for the anti form) = 110.0°(assumed); (2) bromoacetyl bromide, r(C-H) =1.110(0.088) Å, r(C=O) = 1.175(0.013) Å, r(C-C) = 1.513(0.020) Å, r(CO-Br) = 1.987(0.020) Å, r(CH2-Br) = 1.915(0.020) Å, ∠C-CO = 129.4(1.7)°, ∠CH2-CO-Br = 110.7(1.5)°, ∠CO-CH2-Br = 111.7(1.8)°, ∠H-C-H = 109.5°(assumed), ∠ø (gauche torsion angle relative to 0° for the anti form) = 105.0°(assumed). The structural results are discussed in connection with the structures of related molecules. 相似文献