Influence of the nature of the lower free orbital of platinum(IV) bipyridyl complexes on the kinetics and the mechanism of electron transfer processes in which they participate

The kinetics of outer-sphere electron transfer reactions with the participation of [PtEn_xbipy_2–xCl₂]²⁺ complexes (x = 0–2) have been studied. The formal potential and the internal barrier of self-exchange reactions with the electron Pt(IV) Pt(III) have been estimated. A correlation has been shown to exist between the parameters of outer-sphere and intramolecular electron transfer.A. I. Gertsen Russian Fedagogical University, Leningrad. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 5, pp. 695–698, November–December, 1991. Original article submitted May 20, 1991.     

Reactions of lycoctonine alkaloids with acetic anhydride and p-toluenesulfonic acid

The reactions of alkaloids having a 7,8-diol system — lycoctonine, browniine, and dihydromonticoline — with acetic anhydride and p-toluenesulfonic acid have been studied. The optimum conditions for this reaction, leading to anhydro compounds, have been found.Abuali ibn Sino [Avicenna] Tadzhik State Medical Institute, Dushanbe; Institute of Chemistry, Baskir Scientific Center, Urals Branch, Academy of Sciences of the USSR, Ufa. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 545–547, July–August, 1991.     

Theoretical investigation of mechanism of antioxidant action of sterically hindered phenols

Heats of reaction describing the mechanism of antioxidant action of phenols in polyolefins have been calculated by the MNDO quantum-chemical method. It has been shown that reactions producing substituted quinones will proceed the most readily. The influence of substituents on the heat of reaction has been investigated.Vilnius University. Materials, Tambov. Translated from Teoreticheskaya i 8ksperimentaI'naya Khimiya, Vol. 27, No. 2, pp. 165–170, March–April, 1991. Original article submitted February 16, 1990.     

Kinetic aspects of trace-component oxidation in environmental protection

Many and varied kinetic laws apply for the extensive oxidation of small amounts of organic compounds on platinum catalysts. Kinetic models for mixture oxidation are sometimes predicted on a principle for simple interaction between individual reactions. The transient response preceding the stationary state has been examined for various such reactions, which gives information for the kinetic models and also shows that the mechanisms are various. These models can be used in industrial catalytic purification.Zelinskii Organic Chemistry Institute, Russian Academy of Sciences, Moscow. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 5, pp. 525–535, September–October, 1991. Original article submitted July 12, 1991.     

Electronic factors in (4 + 2)-cycloaddition reactions of phosphaalkenes

Reactions involving the (4 + 2)-cycloaddition of phosphaalkenes to 1,3-butadiene have been characterized in the framework of the frontier-orbital approach. MNDO and nonempirical calculations in the 4-31G basis have shown that most of these reactions take place under normal electronic conditions. The -electronic stabilization energies of the transition states of the reactions have been evaluated. The influence of substituents on the relative rate and regioselectivity of the reactions of phosphaalkenes with derivatives of 1,3-butadiene has been considered.Institute of Organic Chemistry, Academy of Sciences of the Ukrainian SSR, Kiev. Scientific-Research Institute of Technical Physics, Far-Eastern University. Vladivostok. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 4, pp. 462–466, July–August, 1991. Original article submitted October 12, 1990.     

Reactivity of 2-diethylaminomethylphenol and its copper(II) complex in the reaction with 4-nitrophenylbis(chloromethyl)-phosphinate

The kinetics of reactions of 2-diethylaminomethylphenol (I) and its Cu²⁺ complex (with a metal: ligand composition of 12) (II) with 4-nitrophenylbis(chloromethyl)-phosphinate have been studied in aqueous-ethanolic media (10–70 vol. % ethanol); bimolecular rate constants have been calculated for the reactions of different forms of compound (I) and complex (II). It was shown that compound (I) in aqueous-ethanolic media is a nucleophilic catalyst for hydrolysis of 4-nitrophenylbis (chloromethyl)-phosphinate. The reactivity of complex (II) is an order of magnitude greater than that of the zwitterion form of the ligand which exists in the same range of pH 7–9.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 555–560, March, 1991.     

Molecular crystal structure and chemical properties of 4-phenyl-3,5-diethoxycarbonyl-1,2,6-trimethyl-1,2-dihydropyridine

The molecular crystal structure of 4-phenyl-3,5-diethoxycarbonyl-1,2,6-trimethyl-1,2-dihydropyridine has been investigated by x-ray structural analysis. The three-dimensional structural properties of the molecule have been compared against the large observed reactivity of the 3-ethoxycarbonyl group with respect to nucleophilic substitution reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1236–1239, September, 1991.     

Reactions of P(III) thiobenzyl esters with methyl iodide

The reactions of S-benzyl diphenylthiophosphinite and 2-benzylthio-4,5-benzo-1,3-dioxaphospholane with methyl iodide have been examined. In contrast to the oxygen analogs, the reaction occurs under mild conditions, and does not give Arbuzov reaction products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2856–2857, December, 1991.     

A new synthesis of the pheromone of the codling moth — Dodeca-8E,10E-dien-1-ol — Via an enynic intermediate

A new method has been developed for the synthesis of the main component of the pheromone of the codling moth — dodeca-8E,10E-dien-l-ol — using in the key stages Wittig reactions and the trans-hydride reduction of the triple bond of an intermediate enynol.Institute of Organic Chemistry, Academy of Sciences of the Armenian SSR, Erevan. Institute of Organic Chemistry and Biochemistry, Academy of Sciences of Czechoslovakia, Prague. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 117–123, January–February, 1991.     

Dissociation processes and factors causing the stabilization of complexes in solutions

The factors causing the thermodynamic and kinetic stability of complexes of metal ions in various media have been discussed. It has been shown in the case of the protolytic dissociation reactions of the porphyrin, tetraazaporphyrin, and phthalocyanine complexes of magnesium, zinc, and copper that the decisive role in the kinetic stabilization of these compounds is played by the rigid structure and the extensive system of conjugation in the macrocyclic ligand.The material was presented at the 17th Chugaev Conference on the Chemistry of Complex Compounds, Minsk, 1990.Ivanovo Chemical-Engineering Institute. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 3, pp. 270–278, May–June, 1991. Original article submitted February 25, 1991.     

Synthesis and anticholinesterase properties of new derivatives of lupinine and elipulinine

Esters of lupinine and epilupinine have been obtained by their acylation with isovaleroyl, cinnamoyl, trichloroacetyl, and trimethylacetyl chlorides. The methiodide derivatives of these esters have been investigated in reactions with the blood cholinesterases of warm-blooded animals. The interaction has a reversible nature, and the inhibition of the activity of the enzyme is both quantitative and qualitative in dependence on the structure of the acid taken and the conformational properties of the lupinine epimers.A. S. Sadykov Institute of Bioorganic Chemistry, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 64–67, January–February, 1991.     

Theoretical analysis of structure and energetics of intermediates in catalytic reactions of alkanesulfonylation

Combined methods of quantum chemistry and molecular mechanics have been used to investigate the structure and energetics of formation of sulfene, and also N-methanesulfonylpyridinium and oxypyridinium halides, which are intermediates in catalytic alkanesulfonylation reactions. The potential energy surface of ion-ion interactions of N-methanesulfonylpyridinium halides has been analyzed. The results have been applied in identifying kinetically indistinguishable mechanisms of general basic and nucleophilic catalysis in processes of alkanesulfonylation of phenols.Institute of Physical Organic Chemistry and Coal Tar Chemistry, Academy of Sciences of the Ukrainian SSR, Donetsk. Donetsk University. Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 27, No. 2, pp. 159–165, March–April, 1991. Original article submitted November 9, 1989.     

Study of processes of interaction of aromatic compounds with the surface of manganese oxide catalyst

The scheme of the oxidative transformations of toluene, ethyl- and propylbenzene, and styrene during their chemisorption from a helium-oxygen mixture on the surface of a hydrated manganese dioxide under precatalysis conditions has been experimentally substantiated. These reactions lead to the formation of benzoate (toluene) or benzoate and formate (ethyl-, propylbenezene, styrene) structures on the surface.L. V. Pisarzhevskii Institute of Physical Chemistry. Ukrainian Academy of Sciences, Kiev. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 5, pp. 541–548, September–October, 1991. Original article submitted June 21, 1991.     

Nitration equilibrium in the meso-erythritol-aqueous nitric acid system

Twelve equilibrium constants have been measured from 16 for sequential-parallel reactions in meso-erythritol nitration to the fully nitrated compound in aqueous HNO₃. Free-energy changes during nitration of the aliphatic polyatomic alcohols, glycerol and meso-erythritol, are highest when diprimary dinitrates (NOON) and (NON) are produced.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2248–2253, October, 1991.     

gem-Dinitro compounds in organic synthesis. 2. Synthesis of 4-nitropyrazoles from dinitromethane and its derivatives

A series of 4-nitropyrazoles was synthesized from dinitromethane and other gemdinitro derivatives. New cyclization reactions of aliphatic azines with dinitro-methane and an intramolecular cyclization of dinitroacetazines have been discovered, with which 4-nitropyrazoles substituted at the 3- and 5-positions of the pyrazole ring can be obtained in one stage.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2825–2828, December, 1991.     

Photoproduction of homogeneous chromium(V) compounds in pentanol for targets containing polarized hydrogen nuclei

Measurements have been made on photochemical and subsequent dark reactions with an He-Cd laser (44l nm) with ammonium dichromate solutions in pentanol. Exposing the solution directly in the spectrometer cavity leads to an ESR signal having g = 1.973 characteristic of chromium(V) compounds. The compounds have been examined by ESR and optical spectroscopy. A kinetic analysis is presented. It is suggested that homogeneous Cr(V) compounds are formed. No Cr(III) or other paramagnetic products have been detected. These compounds can be used in polarized nuclear targets.Joint Nuclear Research Institute, Dubna. Pisarzhevskii Physical Chemistry Institute, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Teoreticheskaya i Éksperimental' naya Khimiya, No. 1, pp. 60–65, January–February, 1991. original article submitted November 17, 1987.     

Trifluoromethyl-p-tolyldiazomethane in 1,3-dipolar cycloaddition reactions

Trifluoromethyl-p-tolyldiazomethane (I) forms [3+2]-cycloadducts with activated alkenes and alkynes. The products of these regiospecific reactions are substituted pyrazolines (II)–(VI) and pyrazoles (VIII)–(X). Reaction of (I) with fumarates, trifluoropyruvates and allyl chloride is accompanied by elimination of N₂ and formation of a 1,2-bis(trifluoromethyl)stilbene. The results obtained indicate that (I) enters only the HOMO-controlled 1,3-dipolar addition reactions.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1589–1593, July, 1991.     

Analysis of the electron density redistribution in the course of nucleophilic addition reactions of H− and F− to acetylene and methylacetylene molecules according toab initio calculations

Energy characteristics and peculiarities of variation of structural parameters along the minimum energy pathways (MEP) calculated earlier of six reactions of nucleophilic addition of H^– and F^– to acetylene and methylacetylene have been analyzed. The electronic mechanism of the reactions, the character of the electron density redistribution, and its relation with the changes in structural parameters have been discussed. It has been found for all six reactions that the structural reorganization of an alkyne + Nu system is completed before the barriers. However, the increase in the alkyne multiple bond length and changes in electronic characteristics for the reactions with F^– (endothermic reactions) take place before the barrier (late transition state) and for the reaction with H^– (exothermic reactions), after the barrier (early transition state).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2373–2377, December, 1995.     

Double phosphate crystallization in phosphate liquids

The discussion concerns the interactions of oxides of metals in groups III–VIII not with individual molten phosphates but with mixtures of them, which provides a range in M₂O:P₂O₅ in the phosphate liquid from 0.5 to 2.0; this constitutes a new approach to these reactions, and it enables one to determine unambiguously the ranges in which double phosphates are formed and to define the conditions under which the individual crystals are produced from those liquids.Kiev University. Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 27, No. 3, pp. 307–311, May–June, 1991. Original article submitted February 19, 1991.     

1,3,4-Thiadiazines: Methods of synthesis and reactivity (review)

The synthetic methods for 1,3,4-thiadiazines and their intramolecular rearrangement reactions are reviewed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 435–448, April, 1991.