Kinetics and products of the reaction of diazo compounds with SO2

Data were obtained on the composition of products and kinetics of the reaction of SO₂ with Ph(R)CN₂ (R=Ph, Me) in solutions of isooctane, 1,4-di-oxane, and ethanol at 295 K. A mechanism was proposed for the process in accordance with which the sulfene being formed participates in concurrent reactions with the starting reagents. The relative rate constants for the process stages were determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2496–2500, November, 1990.     

29Si NMR study of the surface of pyrogenic silica modified by methylchlorosilanes

Cross-polarization ²⁹Si NMR spectra have been used for aerosil modified by methylchlorosilanes to identify surface organosilicon compounds and their reactions during hydrolysis and methanolysis.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, No. 3, pp. 378–383, May–June, 1986.     

The mechanism of oxidation of indoxyl and its analogs to indigo and indigoides

Conclusions Intermediate formation of 3-oxynaphthenyl-2 radical during oxidation of 3-oxythionaphthene to thioindigo was demonstrated by the inhibitor method. The 1:1 recombination product of this radical and diphenylpicrylhydrazyl was isolated. It is assumed that the postulated oxidation mechanism is general for compounds possessing a methylene group bonded to an electron-donating X group and an electron-accepting C=O group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1168–1170, May, 1970.     

Urinary excretion of methylated purines in man and in the rat after the administration of theophylline

Chromatographic characteristics of urinary metabolites of theophylline were studied by two-dimensional thin-layer chromatography, high-performance liquid chromatography and gas chromatography--mass spectrometry. Quantitative date for the urinary metabolites of theophylline in asthmatic children are given. It was shown that 1,3-dimethyluric acid is the predominant excretory product. In addition, smaller amounts of 1-methyluric acid, 3-methylxanthine and unchanged theophylline were found. Excretory patterns after theophylline ingestion before and during the administration of allopurinol in asthma patients and in rats suggest the existence of three metabolic pathways of theophylline. The administration of this drug to a patient with xanthine oxidase of theophylline. The administration of this drug to a patient with xanthine oxidase deficiency resulted in the excretion of 1-methyluric acid in addition to 1,3-dimethyluric acid, 3-methylxanthine, 1-methylxanthine and unchanged theophylline. It was concluded that in man the oxidation of theophylline is not catalysed by xanthine oxidase.     

Topochemical investigations of peptide systems

The basic principles of the topochemical approach to the investigation of the structure-function relation in peptide systems are formulated. This approach makes use of the new possibility of transforming natural peptides, consisting in the modification of the molecule as a whole and utilization of the resultant analogs to elucidate the boundaries of the stereoelectronic complementarity of the biologically active peptide to the corresponding receptor. In particular, on the example of depsipeptide antibiotics and their topochemical analogs the fruitfulness of using such compounds as tools in elucidating the physicochemical basis of functioning of biological membranes is shown. The topochemical principle has also been applied in preparing specific competitive inhibitors of proteolytic enzymes, whose study may shed light on the nature of the forces binding the substrate to the contact site of the corresponding enzyme.