Density functional and spectroscopic studies of nitrogen inversion in substituted dizocilpines

While developing a synthesis towards tagged dizocilpine (MK‐801) analogues, we observed highly restricted inversion of a nitrogen centre in a number hydroxylamines obtained as key intermediates. These compounds are shown to possess some of the structural elements which are expected to significantly hinder the nitrogen inversion, potentially leading to hydroxylamines with a chiral nitrogen centre. Free energy barriers (ΔG^≠) of the nitrogen inversion were estimated to be ca. 22 kcal mol^?1 at temperatures near 420 K using variable temperature NMR measurements in DMSO‐d₆. Further density functional studies of a number model systems were undertaken in order to better rationalize the measured inversion barriers and follow the role of various structural factors in raising the barrier height of the nitrogen inversion process. Copyright © 2008 John Wiley & Sons, Ltd.     

Use of electrolysis under pressure for destructive oxidation of phenol and azo dyes

Trends in the development of electrochemical methods for solving environmental problems were considered. Modern tendencies in research on the electrochemical destruction of toxic organic substances resistant to oxidation were analyzed. The use of three-dimensional (3D) electrodes and combined methods (electro-Fenton process combined with ultrasound, UV irradiation, etc.) increases the efficiency of destruction. Special attention was paid to studies at increased pressures. Increased pressure initially created with an inert gas did not substantially affect the kinetics of the anodic process. Increased pressure initially created with an electrochemically active gas (oxygen) accelerated the anodic oxidation of organic compounds (phenol and azo dyes (direct black 2S and stable disperse yellow 4K). The organic substances under study inhibit the cathodic reduction of oxygen, and the positive role of increased pressure is proven.     

Strong coupling constants of light pseudoscalar mesons with heavy baryons in QCD

We calculate the strong coupling constants of light pseudoscalar mesons with heavy baryons within the light cone QCD sum rules method. It is shown that sextet–sextet, sextet–antitriplet and antitriplet–antitriplet transitions are described by one universal invariant function for each class. A comparison of our results on the coupling constants with the predictions existing in literature is also presented.     

Interactions of benzoxazolin(benzothiazolin)ones and-thiones with α-bromopropionyl chloride

At interaction of benzoxazolin(benzothiazolin)ones with -bromopropionyl chloride N-acylation takes place, while in the case of benzoxazoline(benzothiazoline)thiones, the reaction is accompanied by S-alkylation.Plant Substance Chemistry Institute, Academy of Sciences of the Uzbekistan Republic, Tashkent 700170. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 270–273, February, 1999.     

Use of gas-liquid chromatography for analyzing products of carbonylation of certain pyridine bases

A method has been elaborated for the quantitative gas-chromatographic analysis of a mixture of piperidine, N-formylpiperidine, and pyridine on polyethylene glycol-4400 applied onto a chromosorb and NaCl, and apezon L, applied onto NaCl. The relative retentive volumes and heats of solution of the components of the mixture were calculated.     

<Emphasis Type="Italic">N</Emphasis>-shaped voltage-current characteristic and current oscillations in Sm<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript> Sr<Subscript>x</Subscript>MnO<Subscript>3</Subscript> manganite

The voltage-current characteristics (VCC) of Sm_1?xSr_x MnO₃ samples with x=0.425 and x=0.450 were experimentally studied at a temperature of 77 K in pulsed and constant electric (E) and magnetic (H) fields up to 10 kOe for the H‖E and H⊥E orientations. N-shaped VCCs and high-frequency (up to 3 MHz) current oscillations were observed. It was found that the effect of colossal magnetoresistance had a threshold character and was smoothly reduced to zero with E→0.     

Representability of Analytic Functions in Terms of Their Boundary Values

Suppose that is an arbitrary finite complex Borel measure on the interval is its Poisson integral, and are the conjugate harmonics of , and is the nontangential limiting value of the analytic function as . In this paper, we consider the problem of representing the analytic function in terms of its boundary values .     

Investigations into the Molecular Relaxation Processes in Lithium and Sodium Perchlorates by the Raman Scattering Method

The molecular relaxation processes in crystalline lithium and sodium perchlorates are investigated in the region of totally symmetric ₁(A) ClO₄ ^–-anion oscillations by Raman light scattering spectroscopy. It is demonstrated that the reorientation in LiClO₄ and NaClO₄ represents an activation process. A premelting phase is detected for sodium perchlorate.