共查询到20条相似文献,搜索用时 31 毫秒
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Reaction of 2-t-butylthiobenzaldehyde with N-(2-dialkylaminoethyl)-cyanacetamides followed by heating of the resulting 3-(2-t-butylthiophenyl)-2-cyanoacrylamides in polyphosphoric acid leads to the formation of 3-carboxamido-2-imino-2H-benzo[b][l]thiopyrann intermediates which afford thiocoumarins on hydrolysis. The authors postulate the intermediate formation of a thiophenate ion by an electronic mechanism involving six centers. 相似文献
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Influence of the intrinsic properties of calixarene ligands on catalytic reactions involving ethylene. This review shows how the particular structural and chemical properties of calix[4]arene-derived ligands can be exploited in the catalytic transformation of ethylene into dimers, oligomers, and polymers. 相似文献
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Daniel Davoust Marcel Massias Darius Molho Nicole Platzer Jean-Jacques Basselier 《Magnetic resonance in chemistry : MRC》1978,11(11):547-550
Interaction of lanthanide salts with phenols in DMSO solution was investigated as a tool for 1H NMR structure determination in the field of naturally-occurring polyphenolic compounds. Intermolecular competition experiments evidenced reactivity differences with respect to the nature and position of substituents. Empirical rules of reactivity are suggested from which variations observed in the PMR chemical shifts on addition of lanthanide salts to natural polyphenols (flavones, xanthones) were rationalized. 相似文献
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Catherine Verchre Michel Hocquaux Claude Viel 《Journal of mass spectrometry : JMS》1978,13(10):556-563
We have determined the characteristic fragmentations in a series of 3,4-dihydroisoquinoline and of 8,13 diazaestrones, with the aid of metastable ions, ‘simili’ mass analysed ion kinetic energy spectra (E/V2 constant) and some deuterated compounds. In the diazasteroidal series, we could distinguish three essential types of fragmentation, as well as preferential abstraction of the hydrogen situated on the 14-carbon. 相似文献
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The mass spectra of the three cyclopentane-1,2,3-triols, six cyclopentane-tetrols and four cyclopentane-pentols stereoisomers have been studied. Complex processes, especially regarding the H2O eliminations, were detected by extensive deuterium labelling. 相似文献
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Elisabeth Seguin Michel Koch Alain Ahond Jean Gulhem Christiane Poupat Pierre Potier 《Helvetica chimica acta》1983,66(7):2059-2068
Circular Dischroism of Heteroyohimbane-Type Alkaloids Circular dichroism cannot be used directly to determine the C (3)-configuration of heteroyohimbines. A preliminary chemical transformation is necessary. 相似文献
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Jacques Gilbert Dominique Rousselle Charles Gansser Claude Viel 《Journal of heterocyclic chemistry》1979,16(1):7-11
A new snythesis of 6H-pyrido[4,3-b]carbazoles is described starting from substituted cyclohexanones involving the combination of Borsche's carbazole preparation and Cranwell and Saxton's ellipticine synthesis where the starting materials are easily available. The dehydrogenation step is accomplished at an early stage. In some cases (11-desmethyl ellipticines derivatives), 7H-pyrido[3,4-c]carbazoles were also obtained. 相似文献
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Par Bernard Spiess Franoise Arnaud-Neu Marie-Jos Schwing-Weill 《Helvetica chimica acta》1980,63(8):2287-2294
Stability in Methanol and Thermodynamic Transfer Properties of the Cryptates of some Transition Cations and Heavy Metals The nature and stability of the macrocyclic and macrobicyclic complexes of Ag+, Cd2+, and Pb2+ (Mn+) with 21, 22, 211, 221 and 222 in anhydrous methanol 0.05M in Et4N+ClO?4, at 25° (see Scheme) have been determined by potentiometry and spectrophotometry. Binuclear complexes M2L2n+ have been observed in all cases, besides the mononuclear MLn+ complexes. The macrobicyclic 1:1 complexes MLn+ exhibit an important ‘cryptate effect’ with Mn+=Ag+, Pb2+ and Cd2+, but not with Cu2+ and Zn2+; their stability is in all cases maximum with 221. The applicability to our results of the recent extrathermodynamic hypothesis involving MLn+ cryptates is examined. 相似文献
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J. P. Moliton C. Boutinaud J. C. Vareille J. L. Decossas J. L. Teyssier B. Delaunay 《Journal of Polymer Science.Polymer Physics》1982,20(7):1313-1326
The kinetic interpretation of the damage produced by heavy ions (Kr and Cl from 1 MeV/amu) and γ radiation in cellulose triacetate leads to an exponential dependence on the ion fluence. A comparison of the fading effect produced by heavy ions and γ rays shows that the heavy ions, unlike γ rays, cause irreversible damage. Finally, a nonlinear dependence on the flux of ions and γ rays is found in the kinetics of radiation damage. This result is contrary to the usual assumption that heavy-ion flux, like γ-ray flux, is additive, at least for the fluxes of 109?2 × 1010 ions/cm2s and dose rates of 103–104 Gy/h used in this work. 相似文献
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The volumes of mixing of hexadecane and each of the isomers of hexane have been measured for the equimolar mixtures at 20°C. The results have been used together with previously measured values of ΔH to obtain ΔUv. A very good correlation is found between the energy of mixing and the properties of the pure alkanes. 相似文献
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The adducts of benzoyl chlorides p-substituted by CH3O? , CH3? , and H? with the electronic acceptors SbCl5 and TiCl4 have been prepared, and the IR. absorption spectra of the solid products studied. 相似文献
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The following heats of mixing have been measured: the five isomers of hexane with n-dodecane at 10°, 20° and 30°C, and with n-hexadecane at 20°C, as well as the systems dodecane-hexene-1 at 20°C, and dodecane-methyl-2-pentene-1 at 10° 20° and 30°C. 相似文献
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The present paper deals with the experimental and theoretical determination of energies of conjugation of organic molecules.A computation process has been applied, first to simple molecules comprising an hydrocarbon (styrene), an oxygen function (benzaldehyde) and a nitrogen function (aniline). The results are compared with those obtained from the literature.The application of this computation process to naphthoic acids permits the determination of energies of conjugation and isomerization of these molecules.
Résumé
Dans ce mémoire, il est question de déterminer l'énergie de conjugaison de molécules organiques par voie expérimentale et théorique.Le procédé de calcul que nous avons utilisé a été tout d'abord appliqué à des molécules simples parmi lesquelles figurent un hydrocarbure, le styrène, une fonction oxygénée, le benzaldéhyde et une fonction azotée, l'aniline. Les résultats obtenus ont été comparés à ceux de la littérature.L'application du procédé de calcul aux acides naphtoīques a permis de déterminer l'énergie de conjugaison et d'isomérisation de ces molécules. 相似文献17.
P. Genard 《Magnetic resonance in chemistry : MRC》1979,12(7):396-398
Hydroxylation of saturated steroids such as androstane and pregnane results in appreciable aromatic solvent shifts for the 18- and 19-methyl protons. Solvent shifts associated with hydroxyl and/or carbonyl groups are in general approximately additive. 相似文献
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The infrared absorption spectra of some dialkyldimethoxystannanes have been investigated in the 400–1500 cm?1 region. The bands associated with vs(SnC2) and vs(SnO2) vibrations have been found at 510–521 cm?1 and 466–475 cm?1. The group of bands between 560 and 620 cm?1 is assigned jointly to va(SnC2) and va(SnO2) vibrations. v(C? O) of the methoxy groups linked to tin appears at 1064–1068 cm?1. 相似文献
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In the acid catalysed hydrolysis of three monoaryl-diazomethanes (p)-nitrophenyl-diazométhane (I), p-chlorophenyl-diazomethane (II), phenyl-diazomethane (III), absence of exchange H-D, solvent isotope effects about 2,6, and general acid catalysis prove that proton transfer is rate determining (A-SE2 mechanism). Like other A-SE2 reactions, the hydrolysis of I is shown to obey the Brønsted catalysis law with a variety of carboxylic acids; for eight of these acids, αB was found to be 0,69 ± 0,06. 相似文献