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.     

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.     

Photophysics of the acid and base forms of rhodamine B

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.     

Nitroxydes—LXXVI: Couplages a longue distance dans les nitroxydes azatricycliques. etude par rpe et rmn. conformation du groupement nitroxyde

Complete determination of all proton hyperfine splitting constants in magnitude and sign, and their specific assignment in two stable rigid nitroxides are presented. Long range γ-splitting has been calculated by an MO method (INDO approximation) and by a modification of a valence bond calculation. The results are consistent with a non-planar and rapidly inverting NO group.     

Fluoroaliphatic esters of fluorosulfonic acid. 4. Reactions of α-fluorosulfatoperfluoro ketones with nucleophilic reagents

-Fluorosulfatoperfluoroethyl isopropyl ketone I and fluorosulfatopentafluoroacetone II react with alkali metal chlorides and bromides to form the corresponding -haloperfluoro ketones as a result of direct nucleophilic substitution.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2066–2069, September, 1990.     

Substituted propanes: V. The vibrational spectra,dipole moments and conformations of 1,2-dichloro-, 1-chloro-2-bromo- and 1,2-dibromopropane

The infrared and Raman spectra of 1,2-dichloro-, 1-chloro-2-bromo- and 1,2-dibromopropane were recorded as liquids, in polar and non-polar solvents and in the crystalline state at low temperatures. The infrared spectrum of a high pressure crystal of 1,2-dibromopropane was recorded at ambient temperature. Dipole measurements were carried out in CCl₄ and C₆H₆solutions.Each of the 1,2-dihalopropanes existed as a mixture of three conformers in the liquid state, the one with the halogens in the anti position was in large abundance. Spectral and dipole measurements revealed a comparatively larger concentration of the two polar gauche conformers in polar solvents. All the compounds crystallized in the anti form. The C-halogen stretching vibrations have been interpreted in detail. Vibrational analyses of the anti conformers have been carried out and a tentative assignment of the majority of the gauche bands has been proposed.