Homolytic dissociation of the carbon-element σ bonds by Grignard reagents

The reaction of 2-ethyl-3-tetrahydrofuryl thiocyanate (I) and triphenylacetonitrile (VIII) with methylmagnesium iodide in ether was studied using GC/MS, PMR and¹³C NMR spectroscopy. The reaction of (I) with CH₃MgI gives the product of the homolysis of the C-S bond, namely, bis(2-ethyl-3-tetrahydrofuryl) disulfide (II), in 81% yield. This reaction is assumed to be general in nature since triphenylacetonitrile (VIII) is also homolytically cleaved by the action of CH₃MgI to give triphenylmethane.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2886–2888, December, 1991.     

Formation of quasistationary states in polyatomic systems

Conclusions The results from our analysis of quasistationary states in real molecules and solid clusters provide us with grounds for stating that the proposed method can be used successfully to predict the number of resonances of form in molecules and to obtain approximate estimates of their characteristics.In studies in this area at the qualitative level, it is easy to establish the genealogy of the resonances (i.e., from which atomic states they have proceeded) and the effective value of the quantum number characterizing one resonance or another. In qualitative analysis, the mutual positions of the resonances are indicated approximately; with increasing number of atoms, the inaccuracy increases. Moreover, without carrying out the calculation, it is impossible to estimate the resonance energy, as it is impossible to distinguish reliably between resonances from collective free states of the discrete spectrum and from the rudiments of resonances.Nonetheless, it is possible to use the proposed method to judge trends in the change of resonances from one compound to another. Particularly valuable, in our view, is the possibility that is offered here for the use of very nearly the entire arsenal of the qualitative LCAO-MO theory.In order to obtain semiquantitative estimates of the characteristics of resonances, a model with potential wells is applicable. In simple cases, calculations using this model can be performed on a microcalculator.Rostov Institute of Agricultural Machinery Construction. Translated from Zhurnal Strukturnoi Khimii, Vol. 32, No. 5, pp. 3–8, September–October, 1991.     

Crystal and molecular structure of hexacarbomethoxycyclopropane

A. N. Nesmeyanov Institute of Heteroorganic Compounds, Academy of Sciences of the USSR. N. D. Zelinskii Institute of Organic Chemistry, Academy of Sciences of the USSR. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 3, pp. 171–173, May–June, 1989.     

IR spectroscopic study of substituent effects in N,N-dimethylhydrazides of aromatic acids

Conclusions An IR spectroscopic study showed that the C=0 values in the spectra of N,N-dimethylhydrazides of aromatic acids, RCONHN(Me)₂, correlate linearly with a regression equation obtained for the unsubstituted hydrazides of aromatic acids, RCONHNH₂. This dependence differs significantly from that for N-methyl-N-aroylhydrazines, in which ,-conjugation in the RC(O)N group is more pronounced.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2353–2355, October, 1987.     

Polysaccharides of brown algae VIII. A study of pelvecyan and sargassan by methylation

Conclusions It has been shown by the methylation method that pelvecyan and sargassan are polysaccharides of similar structures with a high degree of branching of the carbohydrate chains. Fucose, xylose, and galactose are located at the nonreducing ends of their molecules, and mannose and galactose form points of branching of the carbohydrate chains of these polysaccharides.The positions of the bonds between the monosaccharide residues in pelvecyan and sargassan have been determined.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Scientific Center, Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 142–145, March–April, 1974.     

Preliminary analysis of the composition of polysaccharide fractions

Conclusions A simple and convenient method for analyzing polysaccharide fractions isolated from natural sources has been proposed.The method is based on ion-exchange chromatography on DEAE-cellulose and gel filtration on Bio-Gels using small columns and automatic monitoring of the separation with the aid of a flow-through ultraviolet densitometer. The method is characterized by rapidity and good reproducibility.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 4, pp. 203–206, 1969     

Phenyl derivatives of 2-pyrone

Several phenyl dichloropentadienyl ketones containing a hydroxy or methoxy group in the benzene ring as well as a number of 2-pyrones based on them were synthesized. The possibility of the conversion of the latter to the corresponding 2-pyridones on heating them with ammonium salts is demonstrated.See [2] for communication III.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 579–581, May, 1971     

Stereochemical features of diterpene alkaloids in acylation and alkaline hydrolysis reactions

Summary Relative difficulty of saponifying an acetoxy group at C₁ and ease of acylation of a hydroxy group in this position as compared with a hydroxy group C₁₀ has been shown for alkaloids with a lycoctonine skeleton.The anomalously easy saponification of a C₁-acetoxy group in karakolidine acetates is due to the influence of the neighboring C₁₃-hydroxy group.Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 381–383, May–June, 1975.     

A study of 1,2,3,4-tetrahydro-4-azafluorene-3,9-diones

Intramolecular cyclization of the diamides and N,N-dimethylamides of -[indan-1,3-dion-2-yl]benzylmalonic acids (I) has given 1-aryl-2-carbamoyl-1,2,3,4-tetrahydro-4-azafluorene-3, 9-diones and 1-aryl-4-methyl-2-methylcarbamoyl-1,2,3,4-tetrahydro-4-azafluorene-3,9-diones (II). The structure of compounds II was shown by chemical methods: bromination, xanthylation, and hydrolysis in alkaline and acid media, and also by a study of IR and UV spectra.