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991.
Thermal degradation of copolymers of styrene and methyl-vinyl-silane by pyrolysis gas chromatography
Pyrolysis gas chromatographic investigations have been carried out on copolymers of styrene with trimethyl-vinyl-silane and of styrene with dimethyl-phenyl-vinyl-silane, in order to study the mechansims of thermal degradation and the copolymer structures. We have identified the pyrolysis products and measured their relative amounts. The experiments show that the controlling factor in the mechanism of the degradation is the nature of the side-group attached to the carbon atom at which chain scission occurs. If this side-group is phenyl, the main degradation process is depropagation; if it is if it is trimethyl-silyl or dimethyl-phenyl-silyl, intramolecular hydrogen abstraction followed by β scission becomes more important than depropagation. From the point of view of degradation mechanism, the nature of the side-group attached to the carbon atom from which the hydrogen is abstracted is of minor importance.We estimated the average copolymer block length from the amounts of products containing both comonomers as well as from the amounts of trimer composed of the same monomer. 相似文献
992.
993.
994.
The possibility of obtaining dispersed powders of cobalt and zinc-nickel ferrites with particle size of 1-4 m by thermal treatment of the corresponding oxalates was analyzed. Changes in porous characteristics of the ferrites obtained in their thermal treatment were studied. 相似文献
995.
V. N. Charushin G. M. Petrova G. G. Aleksandrov L. G. Egorova A. I. Chernishev E. O. Sidorov N. A. Klyuev O. N. Chupakhin 《Chemistry of Heterocyclic Compounds》1987,23(4):426-435
Dibenzo[d,k]-1,3,6,10-tetraazatetracyclo[7.3.1.02,7.06,13]trideca-4,11-dienes undergo addition reactions at the C(2) carbon atom with alcohols and thiols, accompanied by cleavage of the C-N bond of the imidazoline ring, to generate diquinoxalino[1,2-a2,3-d]pyrrole derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 513–522, April, 1987. 相似文献
996.
Aziridines react with trifluoromethyl hypofluorite at ? 40°C to produce mixtures of 1-(aziridine)carbonyl fluoride and 1-fluoroaziridine , the proportions of which depend on steric effects. Several compounds react with starting materials to give 1, 1′-(carbonyl)bisaziridines . Most compounds and all compounds are isolated. Chemical properties and ir and nmr data of , , are described; the formation of an isocyanate and a substituted urea from a compound is observed. A mechanism for this reaction is suggested. 相似文献
997.
998.
Fluorescence lifetime measurements of rhodamine B in ethanol solution have confirmed the presence of two distinct species dependent on acidity. Rotational diffusion times of these species are identical and we propose that they are the acid and base forms of the dye. Species having identical spectra to these forms have also been obtained in concentration dependent studies and we believe that here, too, the equilibrium is acid—base rather than monomer—dimer as had been suggested. 相似文献
999.
1000.
A. I. Mikaya V. I. Smetanin V. G. Zaikin A. V. Antonova N. S. Prostakov 《Journal of mass spectrometry : JMS》1983,18(3):99-104
A method for structure determination of aliphatic alcohols within mixtures is described. It involves the use of a vapour phase dehydrogenation micro-reactor (Cu, 300°C) located between the chromatographic column and the mass spectrometer or between the injection port and the column. Since primary and secondary alcohols are converted into corresponding carbonyl compounds, they can be readily differentiated from tertiary alcohols and dialkyl ethers. An examination of the mass spectra of alcohols and carbonyl compounds permits the determination of molecular mass, the location of hydroxyl group and the determination of branching at the β-carbon atom. 相似文献