FT IR ATR Study of Molecular Interactions in the Urea/Dimethyl Sulfoxide and Urea/Diethyl Sulfoxide Binary Systems

FT IR ATR spectra of urea/dimethyl sulfoxide and urea/diethyl sulfoxide mixtures in the S=O and N—H stretching vibration regions at different molar ratios have been measured. On the basis of the band deconvolution data, various types of intermolecular associated forms, including dimers and hydrogen-bonded urea–sulfoxide complexes, have been revealed. The latter has been confirmed also by ab initio calculations.     

Hydrocarbomethoxylation of 1-hexene with formic acid and methanol under conditions of phosphoric acid catalysis

Conclusions When the hydrocarbomethoxylation of 1-hexene with formic acid is run at atmospheric pressure and temperatures close to room temperature, in the presence of conc. H₃PO₄, an increase in the relative amount of the latter, as well as an increase in the reaction temperature in the investigated range, both favor an increase in the yields of the methyl esters of the C₇ acids, in particular, those containing two methyl groups on the quaternary carbon atom in the -position. An increase in the relative amount of formic acid also favors an increase in the amounts of these esters in the obtained mixtures of esters.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1116–1118, May, 1971.     

Stevens rearrangement of ammonium salts containing 2-propynyloxy or tert-butoxycarbonylmethyl groups

The Stevens rearrangement of ammonium salts containing 2-alkenyl, 2-alkynyl, or benzyl groups along with 2-propynyloxy or tert-butoxycarbonylmethyl was studied. Under the action of a suspension of sodium phenolate in benzene the salts containing a 2-propynyloxycarbonylmethyl group form 2-propynyl esters of 2-dialkylamino-4-pentenoic acids, whereas with sodium methylate as the basic reagent, rearrangement is preceded by an almost complete transesterification. The salts containing a tert-butoxycarbonylmethyl group undergo almost no transesterification under the action of sodium methylate. The tert-butyl fragment in the ester group of the salt with a benzyl group exerts a fairly strong effect on the regiochemistry of the rearrangement and on the prototropic isomerization of the 3,2-Stevens rearrangement of the salts with 2-butynyl or 3-phenyl-2-propynyl groups.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1321–1326.Original Russian Text Copyright © 2004 by Babakhanyan, Ovakimyan, Grigoryan, Kocharyan.This revised version was published online in April 2005 with a corrected cover date.     

Necessary conditions and a test for the stability of a system of two linear ordinary differential equations of the first order

We use the Riccati equation method for the derivation of necessary conditions and a test for the stability of a system of two linear first-order ordinary differential equations. We consider an example in which our results are compared with the results obtained by the Lyapunov and Bogdanov methods by estimating the norms of solutions via Lozinskii logarithmic norms, and by the freezing method.     

Development of composition and study of properties of a new high-efficiency silicon-containing protective conversion coating on zinc-plated surfaces

The composition was developed for a new high-efficiency silicon-containing protective conversion coating for application to zinc-plated surfaces. It was proven experimentally and theoretically that this new environmentally safe coating is comparable in corrosion resistance and protective power to environmentally hazardous chromate coatings; however, unlike the latter, the former is efficient at high temperatures (to 150°C). For extra protection of a material being coated, it was proposed to additionally apply a new, nontoxic (hazard class 4) organic film based on gallic acid esters.     

Influence of multiphoton detunings from resonance on adiabatic processes in a five-level system

The Schrödinger equation for a five-level system has been analyzed numerically for different values of multiphoton detuning from exact resonances. The range of admissible deviations for which the effect of multiphoton detunings on the eigenstate of the interaction Hamiltonian imitating a three-level system is insignificant has been determined. The effective population transfer and the possibility of double storage of optical information have been demonstrated.     

Four-Photon Adiabatic Excitation of Rydberg States

Propagation of four laser pulses in the five-level ladder system in the case of arbitrary intensities and the different strengths of oscillators is investigated, when one of the eigenstates of the interaction Hamiltonian is formed in the whole volume of the medium. Taking into account the first non-adiabatic correction, the equations of propagation are obtained. An analytical solution of these equations is obtained. The conditions for an effective excitation of the fifth level in the whole volume of medium and the limitations on the interaction parameters are obtained as well.     

On the interference absorption of X-rays in crystals with weak deformations

The problem of Borrmann absorption (anomalous absorption) of X-rays in weakly deformed crystals is considered on the basis of Takagi’s approach to the dynamical theory. Using wave function considerations, the attenuation of rays is represented by exp(−σl) where the attenuation factor σ includes a parameter of the lattice deformation field. The possibility of cases σ = 0 and even σ < 0 is discussed.     

Two comparison criteria for scalar Riccati equations with applications

We establish two comparison criteria for scalar Riccati equations and apply them for obtaining certain requirements to coefficients under which the equations have solutions (both tending to infinity and not). We generalize a part of the Lyapunov theorem on the Hill equation and establish solvability criteria for the Redheffer system.