Peculiarities in the copolymerization of trioxane and epichlorohydrin under the influence of EtB⊖F3 A⊕lEt2

This study deals with the copolymerization of trioxane (TO) and 1-chloro-2, 3-epoxypropane (epichlorohydrin, ECH) catalyzed by EtB^?F₃ A^⊕lEt₂ in toluene. The rate of exhaustion of monomers during copolymerization was measured by gas chromatography. It was established that no homopolymers were formed. The copolymers obtained show a high alkali resistance, indicating a statistical distribution of the ECH in the polymer chain. During the first stages of the copolymerization the ECH is exhausted almost instantaneously, whereas TO is gradually exhausted, finally reaching a certain equilibrium depending both on the quantity of the initial ECH and on the temperature at which the process was carried out. Copolymerization is inhibited at increased ECH levels, and only homopolymerization occurs at a certain critical concentration of ECH.     

Approximate empirical formula for X-ray intensity in radioactive nuclides

Known intensities of X-rays emitted from radioactive nuclides have been plotted against atomic number, and a distinct correlation has been found only for EC-decay type nuclides, as follows: 2.75 Z^1.06>X>0.507 Z^1.06, and X_{most probable}=1.18 Z^1.06, where X is the absolute percentage and Z is the atomic number of the decay product.     

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.     

Imidazoline ring cleavage in 1,3,6,10-tetraazatetracyclo-[7.3.1.02,7.06,13]trideca-4, 11-dienes,leading to the formation of diquinoxalino[1,2-a∶2′,3′-d]pyrrole derivatives

Dibenzo[d,k]-1,3,6,10-tetraazatetracyclo[7.3.1.0^2,7.0^6,13]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.     

A polymer thin-film technique to study the micromorphology of core/shell latexes

A series of poly(styrene)/poly(styrene-co-acrylonitrile) core-shell latexes were synthesized by seeded emulsion polymerization. The dried latex was dissolved in toluene and then cast on the surface of water to form a very thin film (60–90 nm). Phase separation in the thin film was studied by transmission electron microscopy (TEM). Electron micrographs of these thin films yielded fine structure and interesting morphology that was unattainable by ultramicrotoming of the corresponding compression-molded specimens. Glass transition temperatures and percent grafted polystyrene were correlated with the TEM results. As grafting increases, mixing of the two phases improves, with the resulting T_g value being between the two T_g's of poly(styrene) and poly(styrene-co-acrylonitrile).     

Action de CF3 of sur des aziridines N-non substitutees

Aziridines $\text{I}$ react with trifluoromethyl hypofluorite at ? 40°C to produce mixtures of 1-(aziridine)carbonyl fluoride $\text{II}$ and 1-fluoroaziridine $\text{III}$, the proportions of which depend on steric effects. Several compounds $\text{II}$ react with starting materials to give 1, 1′-(carbonyl)bisaziridines $\text{IV}$. Most compounds $\text{II}$ and all compounds $\text{IV}$ are isolated. Chemical properties and ir and nmr data of $\text{II}$, $\text{III}$, $\text{IV}$ are described; the formation of an isocyanate and a substituted urea from a compound $\text{II}$ is observed. A mechanism for this reaction is suggested.