Vol 52, No 11 (2016)

Recent published data on the regulation of the elementary stages of homolytic reactions involving radical species are analyzed in the review. The special focus is made on the application of metal complex compounds to mediating radical reactions and their use in the processes of the controlled synthesis of macromolecules, including functional homo- and copolymers, and also nano-sized polymer structures. Examples are considered and prospects are estimated of the practical application of the reversible inhibition of radical processes, reversible chain transfer, atom transfer reactions involving radicals and metal complexes under industrial conditions, in particular, for the production of polymer high tech materials.

Aniline and its derivatives undergo methylation when treated with dimethyl carbonate in the presence of binder-free micro-, meso-, and macroporous zeolites KNaX, NaY, and HY leading to the formation of N-methyl- and N,N-dimethylanilines.

Model has been suggested of quantitative estimation of steric hindrances value in the reaction of free organic radicals based on building sterical spheres with the radii equal the distances from the reaction sites to the valence-unsaturated atoms of the molecule with accounting for their population with the atoms of the molecular system. Simultaneous consideration of the introduced steric hindrances factor and the values of the effective charges on atoms permits prediction of structures of the symmetric and unsymmetrical dimers.

Strategies of synthesis of pyrrolo[3,4-c]pyridines were developed based on cyclization of 3-phenacyl-4-ethoxycarbonyl(acetyl)pyrrole derivatives reacting with N-methylformamide or formamide, and also on recyclization of pyrrolo[3,4-c]pyrylium salts under the action of ammonium acetate and hydrazine acetate. The influence of substituents in initial reagents on composition of reaction products was studied.

Oxidation with 2,3-dichloro-4,5-dicyanobenzoquinone of 2,4-dihydro-1Н-azeto[1,2-a]quinoline-3,4 -dicarboxylates obtained in the reaction of N-aryl-С,С-disubstituted nitrones with Feist’s acid ester resulted in the formation of 2-vinylquinoline-3,4-dicarboxylates in good yields.

Oxidative dehydrogenation of 1-aryl(hetaryl)-1,2,3,4-tetrahydro-9Н-β-carboline-3-carboxylic acids derivatives with dimethyl sulfoxide leads to the formation of 1-aryl(hetaryl)-9Н-β-carbolines. Simultaneously with the dehydrogenation decarboxylation occurs. At the oxidation with dimethyl sulfoxide of methyl 1-aryl (hetaryl)-1,2,3,4-tetrahydro-9Н-β-carboline-3-carboxylicates methyl 1-aryl(hetaryl)-9Н-β-carboline-3-carboxylates formed whose hydrolysis afforded the corresponding 1-aryl(hetaryl)-9Н-β-carboline-3-carboxylic acids.

Complexes of 5-(4-diphenylphosphinophenyl)dipyrromethene with trivalent cobalt (Ph₂PC₆H₄DP)₃Co (DP for dipyrromethene) were obtained for the first time, and their reaction with dicarbonylrhodium(I) acetylacetonate was investigated. The formed complex [Ph₂P(Rh)C₆H₄DP]₃Co was characterized by ¹H, ¹³С, and ³¹P NMR spectroscopy. The dimensions of the ligand were estimated (by geometry optimization with PM3 method) and of the formed rhodium complex (by 2D diffusion NMR spectroscopy DOSY). The size of the complex makes it possible to detain it on membranes with the pore size of 2 nm providing an opportunity to use it in catalytic processes with subsequent separation of the catalyst and the reaction products in the nanofiltration mode. Test of 1-octene hydroformylation with the use of this catalytic system showed results similar to those with the system Rh–PPh₃ both with respect to conversion in aldehydes and to the ratio of n/iso-products. Thus the fundamental possibility was demonstrated of applying the synthesized complexes in catalysis.

Quantum-chemical study with the use of DFT(B3LYP) method was applied to the process of the formation of cyclic organosiloxane iodides in the reaction of imidazole with 1-(iodomethyl)-1,1,3,3,3-pentamethyldisiloxane. According to the calculations the formation of a fused heterocyclic system is possible only with the participation of a triiodide anion.

Pivalic acid was used as a solvent for aminolysis of poly-substituted 2-(nitroamino)-pyrimidin-4(3Н)-one derivatives with arylamines of low basicity. The reaction did not occur in the other solvents or without solvent. Aminolysis products were obtained in 51–59% yields.

From (4,5-dichloroisothiazol-3-yl)phenylmethanol by Ritter reaction a substituted acetamide was synthesized that at hydrolysis with HCl afforded (4,5-dichloroisothiazol-3-yl)phenylmethylamine hydrochloride. By reaction of (5-arylisoxazol-3-yl)- and 4,5-dichloroisothiazol-3-yl)arylmethanol with thionyl chloride the corresponding (1,2-azol-3-yl)arylchloromethanes were obtained. At treatment with O- and N-nucleophiles chlorine atom in chloromethylеne fragment of obtained compounds was substituted by residues of benzylamine, morpholine, vanillin, and ethoxy group.

At nitration of 1-phenyl-5-methyltetrazole with nitric acid in aqueous solutions of sulfuric acid of 84–96% concentration a mixture forms of 1-(4-nitrophenyl)- and 1-(3-nitrophenyl)-5-methyltetrazoles in a ratio 60: 40. According to kinetic data, the tetrazole ring in the substrate is present in a protonated form. The protonation constants of 1-(4-carboxyphenyl)-5-methyltetrazole at the tetrazole ring and the carboxy group were determined. The Hammet’s electronic constant of the protonated tetrazole ring was calculated.

Computer simulation of conformational transformations of 1,3-dioxane molecule within model single-walled carbon nanotubes (hybrid DFT-method PBE/3ζ) showed that the nanosystem considerably affects the conformational equilibrium and the nature of the main minimum on PES, first of all, because of its diameter. The decrease in the latter led to unusual shift of the conformational equilibrium of 1,3-dioxane to the side of 2,5-twist-form.