Substituent effect on ring proton chemical shifts in PMR spectra of monosubstituted pyridines

The relative chemical shifts of ring protons in PMR spectra of 2-, 3-, and 4-monosubstituted pyridines (in DMSO-D₆) are correlated with the F- and R-constants of the substitutents by using a two-parameter approach. Transmission factors characterizing the transfer of inductive and resonance effects in pyridine, pyrimidine, and s-triazine rings are analyzed.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1520–1523, November, 1989.     

Determination and proof of structure of monosubstituted dihydrosilaazanthrones on the basis of PMR spectra

PMR spectra have been used in establishing the structure of ten bromo-, nitro-, and amino-substituted 10,10-dimethyl-10-sila-2-azaanthrones. Anomalous effects of NO₂ and NH₂ groups adjacent to the carbonyl carbon have been observed and explained; these effects are related to the specific geometry of these molecules.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1532–1535, November, 1985.     

Effect of substituents on the chemical shift of the ring protons in the PMR spectra of monosubstituted sym-triazines

A correlation equation that links the relative chemical shift of the protons of the triazine ring with the F and R constants of the substituents was obtained on the basis of data from the PMR spectra of solutions of sym-triazine and its monosubstituted derivatives [OCH₃, N(CH₃)₂, CH₃, C₆H₅, COOC₂H₅, and CN] in dimethyl sulfoxide (DMSO). The equation was analyzed by comparison with the corresponding equations for monosubstituted benzenes and pyrimidines.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 410–414, March, 1982.     

PMR spectra of azacinnolines

An analysis of the PMR spectra (using double resonance) of the isomeric 3-, 6-, 7-, and 8-methyl and 7-ethyl-5-azacinnolines, and also of 7-methyl-8-azacinno-line has shown the presence in these structures of a considerable localization of the C₅-C₆ and C₇-C₈ bonds, which has been confirmed by the results of a quantum-chemical calculation by the PPP method.Deceased.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 541–543, April, 1980.     

PMR spectra of epoxychalcones

The PMR spectra of the epoxides of chalcone and eight of its 4- and 4-substituted derivatives (CH₃, OCH₃, Cl, and NO₂) and of phenyl vinyl ketone in acetone and carbon tetra-chloride were measured. It is shown that these compounds belong to the trans series and exist in hindered conformations. The transmission effects of the epoxide ring and the carbonyl group in epoxychalcone molecules are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1587–1590, December, 1972.     

Mass spectra of monosubstituted trans-stilbenes

The mass spectra of twenty-eight monosubstituted trans-stilbenes in ortho, meta, para and alpha positions with ? N(CH₃)₂, ? NH₂, ? OCH₃, ? OH, ? Br, ? Cl, ? F, ? CH₃, ? COOH, ? CN and ? NO₂ groups as substituents have been studied. A detailed fragmentation pathway is given for stilbene. This fragmentation, characteristic for most of the substituted stilbenes, takes place either from the molecular or from the [M - Substituent] ion. In o-nitro-, o-methoxy-,α-carboxyl- and α-methylstilbene, however, rearrangement reactions prior to fragmentation influence the fragmentation pattern.     

PMR spectra of N-substituted phenothiazines

The PMR spectra of N-substituted phenothiazines were investigated.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1486–1488, November, 1970.     

PMR spectra of difuroyl peroxides

The PMR spectra of difuroyl peroxides were recorded. It is shown that the introduction of a peroxide grouping in place of an anhydride grouping does not lead to changes in the spectrum.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, p. 163, February, 1974.     

PMR spectra of sulfur-containing 1-organylsilatranes

Conclusions The¹H chemical shifts of sulfur-containing 1-organylsilatranes of type YCH₂Si(OCH₂-CH₂)₃N, where Y RS, RS(O), and of sulfonium salts of the silatrane series of type [YCH₂Si-(OCH₂CH₂)₃N]I^–, where Y = RRS⁺, are determined by the valence state of the sulfur atom and the steric stresses. The molecular conformation of the studied compounds was established.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 464–467, February, 1979.     

PMR spectra of natural stilbene compounds

Summary 1. The PMR spectra of 13 natural stilbenes have been studied.2. The dominating role of -electron interaction of the fragments of the stilbene molecule in the screening of the aromatic and olefinic protons has been shown. A series of increments presenting interest for determining the structure of stilbene compounds is proposed.3. It has been established that the nature and nature and number of the substituents in the aglycone part of the molecule have no influence on the screening of the anomeric proton of glycosidated stilbenes, but it does depend on the position of attachment of the carbohydrate fragment.A. A. Zhdanov Irkutsk State University. Irkutsk Institute of Organic Chemistry, Siberian Branch of the Academy of Sciences of the USSR. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 3–10, January–February, 1976.