Quantum-chemical calculations of NMR chemical shifts of organic molecules: IV. Effect of intermolecular coordination on <Superscript>31</Superscript>P NMR shielding constants and chemical shifts of molecular complexes of phosphorus pentachloride with azoles

Intermolecular coordination effects on the ³¹P NMR spectra of molecular complexes of N-vinylimidazole and 1-allyl-3,5-dimethylpyrazole with phosphorus pentachloride were studied by theoretical and experimental methods. The formation of intermolecular dative N→P bond was shown to be accompanied by upfield shift of the phosphorus resonance signal by more than 200 ppm. Appreciable contribution of relativistic effects to ³¹P NMR chemical shifts was revealed; the spin-orbital contribution to ³¹P shielding constant was estimated at >210 ppm. Consideration of solvent effect was found to be crucial while studying steric structure of molecular complexes of azoles with phosphorus pentachloride and intermolecular coordination effects on 31P NMR chemical shifts.     

Dimethylidynemerocyaninocyanines — substituted benzimidazole derivatives

Dimethylidynemerocyaninocyanines — substituted benzimidazole derivatives — were synthesized. A decrease in the basicity of the benzimidazole ring with intensification of the electronegative properties of the substituent gives rise to a small (up to 10 nm) heightening of the color of the dyes obtained. The latter are rather effective spectral sensitizers of silver halide photographic emulsions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 815–818, June, 1984.     

Study of the ultraviolet spectra of some new polybenzimidazoles and model compounds of the benzimidazole series

Summary A study was made of the ultraviolet absorption spectra of some new polybenzimidazoles, containing either aromatic or aliphatic dicarboxylic acid moieties, and also of their model compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 184–187, January, 1965     

Synthesis of Imidazolium and Benzimidazolium Triiodides

Russian Journal of Organic Chemistry - 1,3-(Di)acetonylimidazolium and -benzimidazolium triiodides were synthesized in a one-pot fashion by reactions of imidazole, 3-(1H-imidazol-4-yl)prop-2-enoic...     

Reaction of Imidazoles and Triazoles with 1-(Benzotriazol-1-yl)-2-iodoethanone

Reactions of 2-methyl-1H-imidazole, 1H-benzimidazole, 4H-1,2,4-triazole, and 1H-benzotriazole with 1-(1H-benzotriazol-1-yl)-2-iodoethan-1-one in the absence of a base gave the corresponding N-mono- and N,N′-disubstituted derivatives. 4H-1,2,4-Triazole-3-thiol reacted with 1-(1H-benzotriazol-1-yl)-2-iodoethan-1- one to afford 1-([1,3]thiazolo[2,3-c][1,2,4]triazol-5-yl)-1H-benzotriazolium triiodide.     

Alkylation of 2-Sulfanylbenzoxazole with α-Iodoketones in the Absence of Bases

Reaction of 2-sulfanylbenzoxazole with 1-iodopropan-2-one, 2-iodo-1-phenylethanone, and 2-iodo-1-(thiophen-2-yl)ethanone without solvent and bases afforded bis(benzoxazol-2-yl)disulfonium derivatives in a single preparative stage. The reaction proceeds as a domino-process and includes the alkylation of a sulfanyl group of benzoxazole, the reduction of iodoketone with hydrogen iodide, the oxidation of 2-sulfanylbenzoxazole to disulfide, the alkylation of disulfide atoms of sulfur, and the formation of triiodideanions. The yield of disulfonium derivatives increases twice in the presence of equimolar amount of iodine.     

Thermochemical characteristics of chitosan–polylactide copolymers

The energies of combustion of chitosan and its block-copolymers with different polylactide contents are determined in a static bomb calorimeter. Standard enthalpies of combustion and formation are calculated for these substances. The dependences of the thermochemical characteristics on block-copolymer composition are determined and discussed.     

The effect of space flight on the protein composition of the exhaled breath condensate of cosmonauts

Russian Chemical Bulletin - As a part of development of medicine for extreme situations, we determined, for the first time, the protein composition of the exhaled breath condensate (EBC) of...