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111.
Shihabi ZK 《Electrophoresis》2000,21(14):2872-2878
Discontinuous buffers for capillary zone electrophoresis (CZE) can be used under less rigid conditions compared to those for isotachophoresis for stacking. They can be prepared simply by modifying the sample itself, either by addition of small inorganic ions, low conductivity diluents, or both, and also by adjusting its pH, meanwhile injecting a large volume on the capillary. Zwitterionic and organic-based buffers such as triethanolamine and tris(hydroxymethyl)aminomethane (Tris) are well suited for stacking due to their low conductivity, provided the buffer is discontinuous as demonstrated here. A simple mechanism based on discontinuous buffers is described to explain many of the observed stacking types in CZE, pointing out the many similarities to transient isotachophoresis. 相似文献
112.
The condensation of -substituted acetophenones with benzylidenebisurea in an acid medium has given 5-R-2-oxo-4,6-diphenyl-1,2,3,4-tetrahydropyrimidones. The analogous condensation of propiophenone forms 5-methyl-2-hydroxy-4,6-diphenylpyrimidine. The tetrahydro derivatives obtained are readily dehydrogenated to 5-R-2-hydroxy-4,6-diphenylpyrimidines.For part XX, see [1]. 相似文献
113.
V. M. Lembrikov V. V. Volkova L. V. Konyakhina Z. N. Korneva O. V. Pokidova 《Russian Journal of Applied Chemistry》2005,78(8):1209-1212
Data on the kinematic viscosity of phosphoric acid solutions in technical-grade tributyl phosphate and in an industrial extract from a technological purification system based on tributyl phosphate, which contain 0–18% phosphoric acid in terms of P2O5, at 10–70°C are presented. 相似文献
114.
The synthesis of N-acyl derivatives of γ - keto - α - amino acids (3, 4, 5) by the amidoalkylation of 1,3-dicarbonyl compounds with glyoxylic acid-amide adducts (1, 2) is described. The γ - keto - α - amino acid derivatives (4, 5) were further converted to the corresponding butenolides (6, 7) and to pyrazolylglycine (12). 相似文献
115.
Fenesan I Popescu R Supuran CT Nicoara S Culea M Palibroda N Moldovan Z Cozar O 《Rapid communications in mass spectrometry : RCM》2001,15(9):721-729
This work discusses the synthesis and the fragmentation patterns for 2-(p-acetylaminosulfonamido)-2-thiono-(5,5-dimethyl-1,3,2-dioxaphosphorinane)(1) and for the p-acetylaminosulfonylamides of O,O-diethylthiophosphoric acid (2), O,O-diphenylthiophosphoric acid (3), dimethylaminocyclohexylthiophosphoric acid (4), and diethylaminophenylthiophosphoric acid (5). A thionamidic-thiolimidic structure was attributed to compounds 1-5, consistent with their IR and NMR spectra. EI mass spectra at 70 eV, high resolution (HR) mass measurements and metastable ion spectra were used to elucidate the fragmentation processes and to determine the kinetic energy release values associated with the metastable ion dissociations. HR accurate mass measurements were used to confirm the compositions of the more abundant ions. 相似文献
116.
Pyrolysis of α-phenylacetanilide resulted in migration of the benzyl group to the o and p positions of the aniline nucleus and formation of CO, NH3, toluene benzaldehyde, dibenzyl, trans stilbene, aniline, 9 phenylacridine and 2,3 diphenyl-indole. With o-toluidine as a solvent the previous products were accompanied by 2,3 diphenyl-7-methylindole and 4 amino 3 methyl diphenylmethane. With isoqumoline 1 benzyl isoquinoline and 1,1' bi-isoquinolyl were also obtained.It is concluded that the pyrolysis of phenylacetanilide depends on the homolytic fission of the amide C-N bond into anilino and phenylacetyl free radicals followed by the interaction of the primary and secondary formed radicals with the rearrangement products and solvent nuclei. 相似文献
117.
S. Z. Taits O. A. Kalinovskii V. S. Bogdanov Y. L. Gol'dfarb 《Chemistry of Heterocyclic Compounds》1970,6(11):1367-1372
A mixture of isomers corresponding to closing of the ring at the 3 and 4 positions of the thiophene ring is formed during intramolecular acylation of 12-(5-methyl-2-thienyl)-lauryl chloride in a homogeneous medium; the reaction proceeds primarily to favor the formation of the isomer with the larger ring (80%). A method for the synthesis of macrocyclic -alkylcycloalkanones by reductive desulfurization of the corresponding bicyclic ketones, which contain thiophene rings, was developed.See Izv. Akad. Nauk SSSR, Ser. Khim., 2228 (1970) for Communication XI.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1467–1472, November, 1970. 相似文献
118.
119.
120.
Y.A DemchenkoA Razina Z SedlákovaA Sikora J BaldrianM Ilavský 《European Polymer Journal》2002,38(12):2333-2341
Thermotropic polyesters based on 4,4′-alkane-1-ω-diylbis(4-hydroxybenzoic acid) and 4,4′-(pentane-1,5-diyloxy)dibenzoic acid were studied by dynamic mechanical spectroscopy, X-ray scattering, differential scanning calorimetry and polarizing microscopy. The effect of structure changes in the mesogenic group as well as in the flexible spacer, in particular the incorporation of Cl atoms into the mesogen, introduction of ether oxygen into spacer and the number of CH2 groups in spacer was investigated. More complex mechanical and thermal behaviour was found on second heating scan than on first cooling of the isotropic melt; higher values of mechanical functions were observed in the isotropic state than in the nematic state of melts. While an even number of CH2 groups and the presence of ether oxygen in spacer shifts the transition temperatures to higher values, the incorporation of Cl atoms into the mesogen leads to disappearance of ordered structure and the polymers behave as amorphous materials. 相似文献