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71.
T. I. Yaroshenko V. N. Elokhina A. S. Nakhmanovich L. I. Larina T. N. Komarova S. V. Amosova 《Russian Journal of General Chemistry》2009,79(6):1197-1200
Propargyl bromide with quinoxaline-2,3-dithiol in DMSO in the presence of K2CO3 affords 2,3-bis-(2-propynylsulfanyl)quinoxaline in good yield whereas in absolute methanol in the presence of sodium methoxide at 20°C a 1:2 mixture of 2,3-bis(2-propynylsulfanyl)quinoxaline and 3-(2-propynylsulfanyl)-2(1H)-quinoxalinethione is formed. Individual 3-(2-propynylsulfanyl)-2(1H)-quinoxalinethione was obtained by crystallization of this mixture from ether. The reaction of 1,3-dibromopropyne with quinoxaline-2,3-dithiol in ethanol in the presence of NaOH at heating results in 2-bromomethylidene-1,4-(3H)-dithiino[2,3-b]quinoxaline in 77% yield. Performing this reaction in methanol in the presence of sodium methoxide during long heating (16 h) led to 2,3-bis[(3-bromo-2-propynyl)sulfanyl]quinoxaline in 72% yield. 相似文献
72.
B. V. Chernitsa A. Yu. Ershov D. A. Komarova S. I. Yakimovich V. V. Pakal’nis I. V. Zerova I. V. Lagoda V. V. Shamanin 《Chemistry of Heterocyclic Compounds》2009,45(11):1388-1390
It has been shown by 1H NMR spectroscopic methods that the previously unknown N-methyl-2-amino-benzoyl- and 2-mercaptobenzoylhydrazones of phenylacetic
and 3-phenylpropionic aldehydes have cyclic benzo-1,2,4-triazepine and benzo-1,3,4-thiadiazepine structures respectively. 相似文献
73.
M. E. Perel'son G. G. Aleksandrov L. D. Yakhontova O. N. Tolkachev D. A. Fesenko M. N. Komarova S. E. Esipov 《Chemistry of Natural Compounds》1984,20(5):592-598
The structure of a new spirobenzylisoquinoline alkaloid fromHypecoum erectum L. has been established by spectral methods and also by the x-ray structural analysis of its methiodide. It has been shown that the alkaloid, which has been called hyperectine, has a pentacyclic structure in which the tetrahydroisoquinoline fragment has the sofa conformation and the indan fragment the envelope conformation. The natural alkaloid is a mixture of the enantiomeric C-8(S), C-16(R), and C-8(R), C-16(S) forms.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 628–635, September–October, 1984. 相似文献
74.
V. A. Pankratov Ts. M. Frenkel' A. M. Fainleib Yu. V. Vasil'ev L. I. Komarova 《Russian Chemical Bulletin》1983,32(9):1944-1945
Conclusions 3-Phenyl-5-phenoxymethyl-2-N-phenyliminooxazolidine, formed by the reaction of diphenyl-carbodiimide with phenyl glycidyl ether, reacts with an excess of the latter to give 3-phenyl-5-phenoxymethyl-2-oxazolidone.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2152–2153, September, 1983. 相似文献
75.
The first synthesis of the common trisaccharide of glycoforms of the outer core region of the Pseudomonas aeruginosa lipopolysaccharide is reported. A fully protected trisaccharide precursor was prepared via a highly efficient α-(1→4)-glucosylation of a β-(1→3)-linked 6-O-benzyl-2-azido-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-α-d-galactopyranoside. In contrast, an alternative sequence of glycosylations, which involves β-glucosylation of an α-(1→4)-linked Glc-GalN3 unit, did not lead to the target trisaccharide backbone. Further O-deacetylation, azido group reduction and debenzylation of the protected trisaccharide precursor gave the corresponding trisaccharide amine. The latter structure was used in the synthesis of a series of trisaccharides bearing an acetyl group, an l-alanine or an N-acetylated l-alanine residue on its amino group at C-2 of GalN. 相似文献
76.
Chlorophenoxycarboxylic acid herbicides were separated and determined by capillary electrophoresis. An analysis of a six-component mixture containing 2,4-dichlorophenoxybutyric (2,4-DB), 2,4-dichlorophenoxypropionic (2,4-DP), 2,4,5-trichlorophenoxyacetic (2,4,5-T), 2,4-dichlorophenoxyacetic (2,4-D), and phenoxyacetic (PA) acids and 2,4-dichlorophenol (2,4-DCP), the product of their degradation in aqueous media, took no longer than 15 min. Solid-phase extraction on Diapak C-16 cartridges was used for sample preparation. The detection limits for herbicides in water samples with account for preconcentration (K = 250) were found to be 0.0005 mg/L for 2,4-DB, 2,4-DP, 2,4,5-T, and 2,4-D and 0.001 mg/L for PA. It was shown that humic acids (< 50 mg/L) do not interfere with the determination of chlorophenoxycarboxylic acids. 相似文献
77.
V. A. Pankratov Ts. M. Frenkel' A. E. Shvorak L. I. Komarova A. G. Grozdov V. A. Maslov 《Russian Chemical Bulletin》1990,39(1):118-120
The reaction of phenyl glycidyl ether with phenyl benzoate in the presence of water was investigated by adsorption liquid chromatography.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 131–133, January, 1990. 相似文献
78.
O. V. Okatova N. N. Ul’yanova L. G. Komarova M. P. Prigozhina Yu. N. Sazanov A. L. Rusanov P. N. Lavrenko 《Polymer Science Series A》2007,49(3):349-354
For a number of new polyimides prepared from 3,5-diaminodiphenyl oxide, 2-methyl-3,5-diaminodiphenyl sulfide, and various dianhydrides of aromatic tetracarboxylic acids, the hydrolytic stability in DMF and 96% H2SO4 and the thermooxidative stability in the bulk have been studied. Hydrodynamic techniques have been employed to determine the molecular parameters of these polymers at various stages of degradation. It has been shown that the polymers under study form stable solutions in DMF but turn out to be unstable in 96% H2SO4 even at room temperature. Degradation accompanies dissolution of the polymer. The correlation between the chemical structure of polymer molecules and their hydrolytic stability in both solvents has been established. It has been demonstrated that the majority of the said polyimides are stable in the solid state at temperatures up to 400°C and marked degradation begins only above 500°C. 相似文献
79.
L. I. Komarova N. N. Lapina B. V. Lokshin G. D. Markova V. A. Vasnev 《Russian Chemical Bulletin》1993,42(4):672-676
The interaction of alcohols ROH with esters PhCOOR (R = Me,n-Bu,n-C7H15) in binary mixtures and in solutions in non-polar solvents (CCl4, cyclohexane) was studied over a wide temperature range by Fourier IR spectroscopy. Even with a great excess of alcohol (up to 3000-fold molar excess), two bands are observed in the region ofv(CO) vibrations. The low-frequency band, which is down-shifted by 15–20 cm–1 with respect to thev(CO) band in the absence of alcohol, corresponds to ester molecules bonded by hydrogen bonds of the C=O...HO type. The high-frequency band is up-shifted by 3–5 cm–1 with respect to the esterv(CO) band. The discreteness of the shift, which is confirmed by the appearance of an isobestic point, indicates that an H-complex of yet another type is formed between the alcohol and the ester. The analysis of the data available allows one to conclude that complex formation involves the alkoxyl oxygen atom of the ester. The enthalpies of formation were determined forn-BuOH H-bonds with the esters and with the transesterification catalysts, i.e., As(OBu)3, B(OBu)3, and Ti(OBu)4.Part 3 — see ref.1Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 709–713, April, 1993. 相似文献
80.
A procedure is proposed for the determination of the mass fraction of volatile N-nitrosamines in food by high-performance liquid chromatography with fluorescence detection. A high sensitivity and selectivity of determination is attained by the precolumn operation of obtaining derivatives secondary amines, which were obtained by the denitrosation of initial nitrosamines with 5-dimethylamino-1-naphthalenesulfonyl chloride (dansyl chloride). A mixture of concentrated hydrobromic acid and glacial acetic acid was proposed as the reducing agent for the denitrosation reaction. 相似文献