Study of Features of the Diffraction of X Rays in a Quartz Crystal Modulated by Longitudinal and Transverse Ultrasonic Vibrations

JETP Letters - Features of the simultaneous action of longitudinal and transverse ultrasonic vibrations in the quartz crystal on the parameters of reflected X-rays are studied. It is shown that...     

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.     

Intramolecular 1,5-Hydride Shift in Products of Stevens 3,2-Rearrangement of Ammonium Salts Containing 3-Phenyl-2-propynyl Group

In products of Stevens 3,2-rearrangement of ammonium salts containing alongside alkoxycarbon- ylmethyl also 3-phenyl-2-propynyl group an intramolecular 1,5-hydride shift is observed resulting in immonium salts which transform into aminoesters of enamine structure. The hydrolysis of the latter provides the lower aliphatic aldehydes and the corresponding aminoesters. An acid treatment of the reaction mixture affords a mixture of hydrogenated and nonhydrogenated esters of α-ketoacids originating from the mixture of 1,3-diene aminoesters. At treating with concn. HCl of the obtained mixture the nonhydrogeneted ketoester undergoes cyclization into 4-methyl-3-phenyl-2-buten-1,4-olide.     

Nuclear magnetic resonance spectra of mixtures of 2-monohydroperfluoroisobutane and triethylamine

Conclusions The presence of a strong hydrogen bond between 2-monohydroperfluoroisobutane and triethylamine has been established by the NMR method. Thehydrogen bond shift in this system is not less than 2 p.p.m.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1342–1343, June, 1967.     

High-precision X-ray diffractometer on the base of acoustic monochromator

A new scheme for X-ray difractometer based on acoustic monochromator has been developed and created. The advantages of the new diffractometer are high-level of X-ray monochromaticity, high intensity of diffracted waves, high density of energy flow, and the absence of background.     

Interference absorption coefficient of X-rays in crystals in the presence of temperature gradient

We investigate experimentally and theoretically the behavior of the interference coefficient of absorption of X-ray radiation of a quartz single crystal in Laue geometry in the presence of temperature gradient. The total intensity of transmitted X-ray radiation and that reflected from different families of reflecting atomic planes of the quartz single crystal has been recorded. It was shown that with the increase in temperature gradient the coefficient of absorption of X-ray radiation decreases abruptly reaching its minimal value at a certain value of the temperature gradient.     

Formation of furan derivatives in the course of the Stevens rearrangement of ammonium salts containing 4-allyloxy(phenoxy)-2-butynyl group

Ammonium salts containing phenacyl group in combination with 4-allyloxy(phehoxy)-2-butynyl group, when treated with a suspension of potassium hydroxide in benzene, undergo the 3,2-Stevens rearrangement with the formation of allenic amino ketones which under the reaction conditions give the furan derivatives.     

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.