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The alkylation of tetrabutylammonium acetylacetonate with butyl iodide was studied in order to specify the nature of the reactive anionic species during the nucleophilic reaction of an ambident anion, under similar conditions to those of phase transfer catalysis. The C/O alkylation ratio changes with neither the solvents nor the enolate concentration; however kobs, varies with the solvent but does not depend on the énolate concentration. The results and spectrophotometric UV data show that only one reactive species, the ion-pair, is involved. 相似文献
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A method is described for the determination of hydrogen, oxygen and nitrogen in uranium monocarbide. Hydrogen and oxygen are determined by the classical or modified “Platinum flux” method at 2000° with a coefficient of variation of 10%. Nitrogen is determined at 2000° by the modification of the “Platinum flux” technique. The results obtained are in agreement with those found by Kjeldahl analysis. The coefficient of variation is about 10%. A procedure for the simultaneous determination of the 3 gases is given. 相似文献
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Pierre Brun 《Tetrahedron letters》1977,18(26):2269-2272
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The reaction of fluoride with thorium—SPADNS lake was studied in detail with particular reference to the effects of pH and media. Two methods for the determination of microgram amounts of fluoride based on the reaction are described. The spectrophotometric method developed is more suitable for routine use, but the colorimetric titration method is less sensitive to the effect of large amounts of electrolyte. 相似文献
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A theoretical study of the cycloaddition of ozone on ethylene has been carried out by the LCAO-SCF-MO method. The potential energy hypersurface for the reaction has been investigated and the electronic and energetic properties of the transition state have been determined. 相似文献
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Bernard Boutevin Michel Macret Claude Maubert Yves Pietrasanta Michel Tanesie 《Tetrahedron letters》1978,19(33):3019-3022
A new two-step procedure for the synthesis of ethyl acrylate - vinyl acetate block copolymers is described : the first stage is the telomerisation of ethyl acrylate with carbon tetrachloride by redox catalysis, the second being another telomerisation of vinyl acetate, using the trichloromethyl end group of the first block as the telogen agent, with peroxydic initiation. 相似文献
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Adamantanealkanamines were prepared by a new method: the wittig reaction of aminophosphonium ylides with 2-adamantanone. Conductance measurements have been employed to examine and compare the aggregation behaviour of these compounds. 相似文献
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chromic oxidation of adamantanone gives adamantane-2,6-dione (20%), 5-hydroxy adamantan-2-one (6%) and 5-acetoxy adamantan-2-one (36%). 相似文献
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In a previous paper we have shown that at 740°C and under an oxygen pressure less than 1,3 torr the electrical conductance G of a NiO powder reaches rapidly an apparently stabilized signal Gi which sharply decreases after a sufficiently long time to a G0 value independent of PO2.From this observation we have studied the influence of the temperature successively on the electrical conductance Gi and G0. The Arrhenius law is only verified for the G0 = f(T) curve. G0 appears as the representative value of the gas-solid equilibrium. 相似文献
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The transposition of oxirane-ethanols, through alkoxytin compounds, into oxetane-2-methanols and/or oxolan-3-ols (tetrahydrofuran-3-ols) is dependent upon the oxirane configuration. Cis configuration is more suitable for the formation of the smallest ring. Steric hindrance is not sufficient enough to explain the results. 相似文献
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Adamantane oxazolidine derivatives have been prepared. The corresponding mono and biradicals have molecular shapes well suited to the study of the motion anisotropy in solution. 相似文献
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New derivatives of 4-amino [3,4-d] pyrazolo pyrimidine have been prepared. Mono, di- and tri-substitution products are characterised by unequivocal synthesis. Several compounds are being tested for possible carcinostatic activity. 相似文献
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Irradiations at different wavelengths (313, 254, 229 and 214 nm) of the 4 geometric isomers of 5-phenyl-1,3,5-heptatriene show that the photochemical behaviour of these trienes is mainly controlled by their ground state equilibrium. 相似文献
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The copolymerization of acrylic acid with methacrylic acid in bulk is investigated at 40 and 60°. It is confirmed that a “matrix effect” occurs only for high contents of acrylic acid. The critical concentration beyond which the matrix effect disappears is shifted towards lower acrylic acid contents for higher temperatures. The copolymer composition is independent of temperature. The copolymerization of acrylic acid with methyl acrylate is investigated in a mixture which determines an “exaltation of the matrix effect” in the homopolymerization of acrylic acid (molar fractions: mMonomers = 0.34; mn-Hexane = 0.52; mMethanol = 0.14). The resulting copolymers are found to contain a much larger fraction of acrylic acid residues than the copolymers formed in bulk or in toluene or DMF solutions. 相似文献