Reaction of 1,2‐Dialkyldiaziridines and 1,2,3‐Trialkyldiaziridines with Methyl Propiolate in Ionic Liquids and in Organic Solvents

An interaction of 1,2‐dialkyldiaziridine and 1,2,3‐trialkyldiaziridine with methyl propiolate was studied both in organic solvent (MeCN, CH₂Cl₂, C₆H₆) and in ionic liquids. Earlier unknown linear structures, in which three molecules of methyl propiolate were suited to one diaziridine molecule (adducts 1 : 3), were obtained in MeCN. The diaziridine ring expansion products 1,2,3,4‐tetrahydropyrimidine derivatives (adducts 1 : 2) and, along with them in some cases, the same linear structures were obtained in ionic liquids. A mechanism of reactions found was offered. The regioselectivity of reactions was supposed to determine by the structure of substituents in initial diaziridines. This conclusion was supported by quantum chemical calculations.     

Fluorine spin–spin coupling constants of pentafluorobenzene revisited at the ab initio correlated levels

All possible spin–spin coupling constants, ¹⁹F–¹⁹F, ¹⁹F–¹³C, and ¹⁹F–¹H, of pentafluorobenzene were calculated at five different levels of theory, HF, DFT, SOPPA (CCSD), CCSD, and the SOPPA (CCSD)-based composite scheme with taking into account solvent, vibrational, relativistic, and correlation corrections. Most corrections were next to negligible for the long-range couplings but quite essential for the one-bond carbon–fluorine coupling constants. Hartree–Fock calculations were found to be entirely unreliable, while DFT results were comparable in accuracy with the data obtained using the wave function-based methods.     

Influence of Plasma-Enhanced Chemical Vapor Deposition Parameters on Characteristics of As–Te Chalcogenide Films

First time the method of plasma-enhanced chemical vapor deposition was used for preparation of As–Te chalcogenide films of different chemical and phase composition. The samples were synthesized via direct interaction of arsenic and tellurium vapors into low-temperature non-equilibrium RF (40 MHz) plasma discharge at reduced pressure (0.1 Torr). The plasma parameters such as temperature and concentration of electrons were measured by moving double probe diagnostic system. The dependence of solid phase radial distribution on plasma characteristics was established. Besides, the phase and structural evolution of As–Te films based on equilibrium coexistence of two phases (AsTe and As₂Te₃) and implemented by changing of the ratio of the initial substances in gas phase has been studied and discussed.     

Indirect relativistic bridge and substituent effects from the ‘heavy’ environment on the one‐bond and two‐bond 13C1H spin–spin coupling constants

Indirect relativistic bridge effect (IRBE) and indirect relativistic substituent effect (IRSE) induced by the ‘heavy’ environment of the IV‐th, V‐th and VI‐th main group elements on the one‐bond and geminal ¹³C? ¹H spin–spin coupling constants are observed, and spin‐orbit parts of these two effects were interpreted in terms of the third‐order Rayleigh–Schrödinger perturbation theory. Both effects, IRBE and IRSE, rapidly increase with the total atomic charge of the substituents at the coupled carbon. The accumulation of IRSE for geminal coupling constants is not linear with respect to the number of substituents in contrast to the one‐bond couplings where IRSE is an essentially additive quantity. Copyright © 2015 John Wiley & Sons, Ltd.     

Deflagration-to-detonation transition in narrow channels: hydraulic resistance versus flame folding

This paper is concerned with the identification of the key interactions controlling the deflagration-to-detonation transition in narrow smooth-walled channels. Two agencies contributing to the transition are discussed: hydraulic resistance and flame folding. Depending on the kinetics and parameters of the system, nucleation of detonation may occur near the channel wall and/or in the channel interior. A possibly unexpected outcome of the resistance-folding interplay is the non-monotonicity of the dependence between the predetonation run up time/distance and the channel width.