Anionic polymerization of ɛ-caprolactam in the presence of piperidine N-carboxamides

Piperidine N-carboxamides were shown to activate the anionic polymerization of ?-caprolactam. The activator structure affects properties of the resulting polycaproamide.     

Reactions of Dichlorocarbene and Arenesulfenyl Chlorides with 3,4-Epoxy-1-butene and Vinylethylene Carbonate

Reaction of 3,4-epoxy-1-butene with dichlorocarbene is accompanied by deoxygenation and yields a mixture of 1,1-dichloro-2-vinylcyclopropane, 2,2,2',2'-tetrachlorobicyclopropyl, and 2,2-dichlorocyclopropyloxirane. Arenesulfenyl chlorides react with 3,4-epoxy-1-butene to afford both Markownikoff and anti-Markownikoff addition products, whereas vinylethylene carbonate gives rise exclusively to the anti-Markownikoff adducts.     

Viscosity of Polymer–Bitumen Binders

Polymer–bitumen binders for the highway engineering were obtained by the addition of a ternary ethylene–propylene rubber to a bitumen. The addition of a vulcanizing agent to a polymer–bitumen composition caused the structuring of the system through cross-linking of rubber molecules in the bitumen matrix that was confirmed by the study of structural viscosity of the polymer–bitumen compositions, as well as molecular mobility by the methods of NMR-relaxation and pulsed field gradient NMR-relaxation (self-diffusion).     

DNA separation at a liquid-solid interface

We demonstrate that it is possible to separate a broad band of DNA on a solid substrate without topological obstacles. The mobility was found to scale with molecular size (N) as N(-0.25), while the resolution scaled as N(0.75) indicating that diffusivity on this substrate was minimal. By varying the buffer concentration we were able to show that the mobility for a given chain length scaled with the persistent length (p) as p(1/2). This could be shown to be related to the Gaussian conformation of the chains adsorbed on the surface. A two-dimensional corrugated surface of nonporous silica beads was produced using a self-assembling process at the air/water interface. Even though the surface corrugations were comparable to persistence length we show that they do not affect the mobility, indicating that surface friction rather than topological constraints are the predominant mechanism of separation on a surface.     

Transesterification of Diethyl Carbonate with Methanol Catalyzed by Sodium Methoxide

Russian Journal of Organic Chemistry - The mechanism of sodium methoxide-catalyzed transesterification of diethyl carbonate with metha-nol to dimethyl carbonate has been studied by DFT quantum...     

Catalytic Metathesis of N-Methylformamide with Dimethyl Carbonate by Alcohol Associates

Russian Journal of Physical Chemistry A - The mechanism of N-methylformamide metathesis with dimethyl carbonate, which leads to the formation of N,O-dimethyl carbamate, is studied using the...     

Bulk condensation during heterogeneous reactions

Using the methods of the classical theory of nucleation and an assumed reaction mechanism, the expressions for the rates of nucleation and growth of condensed particles in a particular heterogeneous reaction are derived to describe the kinetics of volume condensation in some complex systems.     

Dynamics of the droplet size distribution function during the gradual creation of a supersaturation state under different regimes of droplet growth

The method of the direct numerical integration of kinetic equations of droplet size distribution functions that was previously proposed by the authors is employed to solve the problem of condensation relaxation in a vapor-gas mixture during the creation of a supersaturation state at a finite rate. Two relaxation regimes are considered. In the static regime, the mixture is expanded at a constant rate until a preset supersaturation ratio is achieved; in the dynamic regime, the expansion is continued. Solutions are obtained for argon-cesium and argon-ethane mixtures, thus making it possible to study the dependence of the process character on the Knudsen number. The effects of the rate of the supersaturation creation and the relaxation regime on the droplet size distribution function are analyzed.     

Quantum-chemical study of isocyanate reactions with linear methanol associates: IX. Methyl isocyanate reaction with methanol-phenol complexes

Quantum-chemical method B3LYP/6-311++G(df,p) was applied to the study of complex formation between phenol and methanol. The complexes of molecules bound by the hydrogen bond possess enhanced donoracceptor and acid-base properties as compared to monomer molecules. The reactions of phenol and methanol complexes with methyl isocyanate proceed through a concerted late asymmetric transition state by the type of nucleophilic addition. The most kinetically and thermodynamically favorable transformation is the process involving the complex “phenol-acceptor, methanol-donor.” Phenol compounds are able to catalyze the addition of alcohols to isocyanates.