On the effect that acoustic boundary conditions have on the structural transitions in nematics in the field of ultrasonic compressional waves

The peculiarities of the structural transition in a homeotropic layer of nematic liquid crystal (NLC) affected by compressional waves in a cell with acoustically soft or hard boundary conditions at its ends have been studied for the frequency range where the wavelength of viscous wave is smaller than the layer thickness, while the wavelength of the elastic wave in NLC exceeds the layer thickness. The data obtained are analyzed within the known theoretical models developed for these two geometries based on the unified hypothesis, which postulates the flow mechanism of the orientational effect of ultrasound on NLC.     

On the mechanism of the effect of ultrasound on a nematic liquid crystal at oblique incidence

Based on an experimental study of the optical response of a homeotropically aligned nematic liquid crystal layer to the action of obliquely incident longitudinal ultrasonic waves, the applicability of the new theoretical model postulating the streaming mechanism of molecule reorientation is justified. It is shown that, in the frequency range 0.9–3.6 MHz, theoretical calculations with the use of this model are in both qualitative and quantitative agreement with experimental data.     

Acoustic Waves and Supramolecular Structures in Liquid Crystals

Crystallography Reports - The achievements in the study of the supramolecular structures arising in liquid crystals (LCs) under acoustic waves, which was started by the work of Professor А.P....     

One-pot oxidative bromination – Esterification of aldehydes to 2-bromoesters using cerium (IV) ammonium nitrate and lithium bromide

A two-step, one-pot reaction of aldehydes with the CAN/LiBr oxidation system under solvent-free conditions followed by the addition of methanol affords methyl α-bromocarboxylates. The oxidation of aldehydes with methanol using this system gives only methyl esters. A facile method, which does not require special equipment, was developed for the synthesis of 2-bromoesters from aliphatic aldehydes with carbon chain lengths of 5–10 atoms.     

Preparation of polyboronphenylsiloxanes by mechanochemical activation

Linear polyboronphenylsiloxanes containing fluorine atom at silicon and acetylacetonate group at boron have been synthesized by mechanochemical activation. Mechanochemical activation of polyphenylsilsesquioxane and boron difluoride acetylacetonate taken in molar ratio 1 : 1 was shown to lead to the formation of polyboronphenylsiloxane with the given Si/B ratio. The products are characterized by gel chromatography, IR, NMR spectroscopy, elemental analysis, and X-ray phase analysis. The increase of the starting ratio Si/B enhances side processes and formation of polydisperse products with the Si/B ratio different from the desired one. The mechanism of the reaction is suggested.     

Synthesis and structure of derivatives of 7-oxo-4,5,6,7-tetrahydrobenzo[b]-thiophene and 7-hydroxybenzo[b]thiophene

The oxidation of 2-acylamino-3-ethoxycarbonyl-4,5,6,7-tetrahydrobenzo[b]thiophenes gave the corresponding 7-oxotetrahydrobenzo[b]thiophenes and some of the transformations of these compounds were studied. These compounds were used for the synthesis of 3-ethoxycarbonyl-6-bromo-7-hydroxybenzo[b]thiophene. The structures of the compounds prepared were established by chemical and spectral methods.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1626–1629, December, 1984.     

Lipids of the root crop Beta vulgaris

The composition and the amounts of various groups of neutral lipids and of glyco- and phospholipids in the root cropBeta vulgaris of the varieties bordeaux and Nosovskaya ploskaya have been investigated by a combination of chromatographic and chemical methods. About 30 groups of lipid compounds were identified, among which free sterols and their glycosides, diand triacylglycerols, monogalactosyldiglycerides and their acyl derivatives, phosphatidylglycetols, phosphatidylcholides, and phosphatidic acids predominated. The fatty acid composition, determined by GLC, was represented by 11 components, of which about 90% consisted of linoleic, palmitic, and oleic acids.A. V. Bogatskii Physicochemical Institute of the UkrSSR Academy of Sciences, Odessa. Translated from Khimiya Priorodnykh Soedinenii, No. 3, pp. 357–360, May–June, 1988.     

Cleavage of spirooxaziridines by the action of ferrous sulfate

The reaction of 2-butyl-3,3-(1-heptyl)tetramethyleneoxaziridine with ferrous sulfate gave the N-butylamides of E- and Z-4-dodecenecarboxylic and E- and Z-5-dodecene-carboxylic acids in –11 ratio. Analogously, 2-butyl-3,3-(1-alkyl)pentamethy1-eneoxaziridines gave the N-butylamides of the corresponding E- and Z-unsaturated carboxylic acids.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 954–958, April, 1991.