Mechanism of Deuterium Distribution in Ethanols

Deuterium distribution in ethanols produced by sulfuric acid hydration of ethylene was studied by quantitative NMR spectroscopy.     

Synthesis of 2-(2-selenienyl)pyrrole from methyl-2-selenienylketoxime and acetylene

The reaction of methyl-2-selenienylketoxime with acetylene in KOH-DMSO gives 2-(2-selenienyl)pyrrole and its 1-vinyl derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 708–710, May, 1992.     

NMR spectroscopic study of the effects of conjugation

Conclusions We have examined the¹³C NMR spectra of para- and meta-substituted alkylthiobenzenes. Steric disruption of the p, -conjugation of sulfur with the aromatic fragment on increase in the size of the alkyl substituents is typical of all the series. The degree of p,-conjugation and the molecular conformation also depend on the electronic effects of the para and meta substituents.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1525–1531, July, 1981.     

Carbon-carbon coupling constants - a new guide in the stereochemistry of oximes

A positive contribution of more than 7 Hz to the direct ¹³C-¹³C spin-spin coupling constants induced by the proximity of the nitrogen lone pair in syn-orientation to the coupled nuclei allows an unambiguous configuration assignment of diverse oximes.     

Quantitative1H and13C NMR spectroscopies of cottonplant dioxane lignin

A comparative analysis has been made of the dioxane lignins of the stems, seedling shoots, and seed coats of the cotton plant. The ratio of p-hydroxyaromatic, guaiacyl, and syringyl units in the macromolecules of the lignins has been determined, and so have the amounts of functional groups and bonds. It has been established that the main difference between the dioxane lignins from seedling shoots and seed coats of the cotton plant, on the one hand, and the lignin from the woody stems, on the other hand is a lower content of syringyl and guaiacyl units in the former.     

Pyrroles from ketoximes and acetylene

The ¹³C NMR spectra of eight 2-alkyl- and 2,3-dialkyl-1-vinylpyrroles were studied. The ¹³C chemical shifts of all of the carbon atoms of the ring and the vinyl group depend substantially on the position and structure of the alkyl substituent. As the branched character of the alkyl group in the 2 position increases, the signal of the -carbon atom of the vinyl group is shifted to weak field due to weakening of the p- conjugation in the N-vinyl group because of disruption of its coplanarity with the pyrrole ring. The conjugation between the double bond and the pyrrole system involves competition for possession of the p electrons of the nitrogen atom.See [16] for communication II.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 350–354, March, 1978.     

Triterpene saponins fromThalictrum minus. V. Structure of thalicoside B

The epigeal part ofThalictrum minus L. has yielded a new bidesmoside — thalicoside B — which has the structure of oleanolic acid 28-O-β-D-glucopyranoside 3-O-[O-α-L-rhamnopyranosyl-(1 → 2)-O-β-D-glucopyranosyl-(1 → 3)-α-L-arabinopyranoside].     

1H and 13C NMR spectra of new 2-thiabicyclo[3.2.0]hept-3-enes

Three new compounds, one with the molecular formula C₆H₈S and two corresponding to C₇H₁₀S have been isolated together with the main product, divinyl sulphide, from the reaction products of acetylene with sodium sulphide. Structure determination through ¹H and ¹³C NMR with selective ¹³C? {¹H} decoupling, showed C₆H₈S to be a new heterocyclic compound, 2-thiabicyclo[3.2.0]hept-3-ene, and the two C₇H₁₀S compounds its exo- and endo-6-methyl derivatives. Since the spectral parameters of these heterocycles were not known, all possible structures corresponding to the molecular formulae were considered.