Neutron powder-profile study of chlorofluoromethane.
The crystal structure of chlorofluoromethane, CH(2)ClF, has been determined at 100 and 30 K using indexing, packing considerations and Rietveld refinement of neutron powder profiles. There is only one phase, in monoclinic space group P2(1) and with two molecules in the unit cell occupying general positions. The structure has close packing in several directions and there are weak hydrogen bonds forming zigzag chains.
Crystal Structure and Spectroscopic Investigation of Bromofluoro‐ and Fluoroiodomethane
The solid states of bromofluoromethane (BFM) and fluoroiodomethane (FIM) are characterized by X-ray diffraction analysis and by Raman spectroscopy. The single crystals were obtained by crystallization in situ at low temperature. BFM and FIM crystallize in the space group I2/a and Abm2, respectively. The Raman spectra of both compounds were recorded in different aggregation states and at different temperatures. Quantum chemical calculations and the X-ray diffraction data are considered to describe the noncovalent interactions of both compounds in the solid state. These interactions are discussed in the context of the σ-hole concept.
Sterol metabolism. XLI. Cholesterol A-ring autoxidations
Abstract Chromatographic and spectral evidence is adduced for the presence of cholest-5-en-3-one, cholest-4-en-3-one, and cholest-4-ene-3,6-dione in samples of cholesterol aged naturally in air or subjected to irradiation in air by 60 Co gamma radiation. These findings establish an additional mode of air oxidation of cholesterol to A-ring 3-ketones. Moreover, the oxidation by air of cholest-5-en-3-one induced by 60 Co gamma radiation yielded cholest-4-en-3-one, cholest-4-ene-3,6-dione, and the epimeric 3-oxocholest-4-ene-6-hydroperoxides. Cholest-4-en-3-one was not altered by irradiation in air, nor was cholesterol isomerized to cholest-4-en-3β-ol upon irradiation. From these observations it is deduced that the radiation-induced A-ring dehydrogenation of cholesterol yields initially cholest-5-en-3-one which upon isomerization yields cholest-4-en-3-one not further oxidized and which by a second oxidation yields the epimeric 3-oxocholest-4-ene-6-hydroperoxides which decompose to cholest-4-ene-3,6-dione.