Kinetic isotope effect and mechanism of catalytic reaction of hydroxybenzenes with epichlorohydrin

Kinetic data are presented for catalytic reactions of 3-nitrophenol and 4,4′-dihydroxydiphenyl sulfone with epichlorohydrin. Magnitudes of the kinetic isotope effects have been determined for these reactions, and a mechanism of catalysis is proposed. Donetsk State University, 24 Universitetskaya ul., Donetsk 340055, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 5, pp. 302–305, September–October, 1998.     

Kinetics and mechanism of the decomposition of cumyl hydroperoxide in the presence of 2-mercaptobenzimidazole

2-Mercaptobenzimidazole reacts with cumyl hydroperoxide to give radicals. This accounts for the initiating effect of this compound in the autoxidation of isopropylbenzene and ethylbenzene. On the other hand, 2-mercaptobenzimidazole is a weak inhibitor in the low-temperature initiated oxidation of alkylbenzenes. Donetsk State University, 24 Universitetskaya St., 340055 Donetsk, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 44–48, January–February, 1997.     

Catalytic activity and mechanism for the action of pyridines in the phenolysis of epichlorohydrin

The reactivity of 3-chlorophenol with epichlorohydrin in the presence of substituted pyridines was studied. The reaction orders relative to the reagents and catalyst were determined. Correlations permitting evaluation of the effect of structure and concentration of the catalyst were obtained. The catalysis mechanism was found. Donetsk State University, 24 Universitetskaya ul., Donetsk 340055, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 2, pp. 89–91, March–April, 1999.     

The α-effect of oximate ions and solvent effect in the transfer of the toluenesulfonyl group in aqueous dimethylsulfoxide

The kinetic behaviour of oximate ions was studied in the transfer of the toluenesulfonyl group in aqueous dimethylsulfoxide (0–95 vol.% DMSO). The solvation effects of the solvent are a factor controlling the nucleophilicity and magnitude of the α-effect of the oximate ions. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 1, pp. 30–35, January–February, 2000.     

α-Effect of hydroxylamine in the transfer of a toluenesulfonyl group in water—Dimethyl sulfoxide mixtures

A kinetic and thermodynamic analysis of the reactions of hydroxylamine with aryltoluenesulfonates in H₂O-DMSO mixtures (0–90 vol.% DMSO) indicated that the neutral and anionic forms of hydroxylamine are strong α-nucleophiles, and the magnitude of the α-effect shows an asymmetric bell shape depending on the DMSO content. This phenomenon is interpreted. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 2, pp. 83–88, March–April, 1999.     

Means of checking for false compensation effects in liquid-phase reactions

A rapid method is presented for revealing a false compensation effect resulting from errors in measurement of the reaction rate constants. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 4, pp. 233–238, July–August, 1998.     

Quantum chemical model for the adsorption of organic molecules on metal surfaces in electrolyte solutions

A quantum chemical model is proposed for the adsorption of organic molecules on metal surfaces in electrolyte solutions. This approach is based on the method of electrostatic images modefied for the case of a double electrical layer within the framework of the PPP method. The calculated data are in good accord with the available experimental results. Donbas State Building and Architecture Academy, 2 Derzhavina ul., Makeevka 339023, Donetsk Oblast', Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 5, pp. 284–288, September–October, 1999.     

Energetic and structural characteristics of N-substituted carbazoles and diphenylamines as components of charge transfer complexes

Geometric, spatial, and energetic characteristics of unsubstituted and some N-alkyl substituted diphenylamines and carbazoles as components of charge transfer complexes have been investigated using semi-empirical quantum mechanical modelling. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 79–81, March–April, 1998.     

Kinetic and thermodynamic interpretation of the reversible reaction of 2,4,6-trinitrochlorobenzene with 4-[4-(dimethylamino)styryl]pyridine in acetonitrile

The energetic and activation parameters for the reversible reaction of 2,4,6-trinitrochlorobenzene with 4-[4-(dimethylamino)styryl]pyridine in acetonitrile were determined. The rate constants for the forward and reverse reactions were found to be equal at 300 K. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, R. Lyuksemburg St., 340114 Donetsk. Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 149–152, May–June, 1997.     

Kinetics of the transfer of the dimethyl-carbamoyl group from N- and O-acylonium salts to azines and their N-oxides

The rate constants and activation energies were determined for a series of reactions involving the transfer of a dimethylcarbamoyl group from the N,N-dimethylcarbamoylonium salts of a series of nitrogen heterocycles and their N-oxides to nucleophiles (azines and their N-oxides) in acetonitrile. The measured values were compared with the structural, reaction, and equilibrium characteristics. L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Chemistry, National Academy of Sciences of Ukraine, Donetsk. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 143–148, May–June, 1997.     

Kinetics of the hydroxylation of N-picryl-4-[4-(dimethylamino)styryl]pyridinium salts by molecular oxygen in acetonitrile

The reactions of N-picryl-4-[4-(dimethylamino)styryl]pyridinium salts with molecular oxygen in the presence of 4-[4-(dimethylamino)styryl]pyridine (DASP) in acetonitrile proceeds with the formation of DASP picrate. The reactions are first-order relative to the salt cation, molecular oxygen, and the catalyst (DASP). L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R, Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 5, pp. 286–289, September–October, 1998.     

Kinetics and mechanism of the reaction of 1-benzoyloxy-4-[4-(dimethylamino)styryl]pyridinium tetrafluoborate with trimethyl-benzylammonium chloride in acetonitrile

The reaction of 1-benzoyloxy-4-[4-(dimethylamino)styryl]pyridinium tetrafluoborate with trimethylbenzylammonium chloride in acetonitrile takes place with the formation of an ion pair of 1-benzoyloxy-4-[4-(dimethylamino)styryl]pyridinium chloride, the slow decomposition of which to the σ adduct is rate-determining. The equilibrium constants of the individual steps of formation of ions from the ionogens PhCOCl and DASPO are determined. L. M. Litvinenko Institute of Physical Organic Chemistry and Carbon Chemistry, National Academy of Sciences of Ukraine, 70 Lyuksemburg ul., Donetsk 341114, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 3, pp. 148–152, May–June, 1998.     

Nonlinear Brönsted relationships and the α-effect of oximate ions in acyl* transfer reactions

A detailed extrathermodynamic analysis of the behavior of oximate ions (pK_a≈7–13) in reactions with various types of substrate was undertaken. For oximate ions with pK_a≥9.0, irrespective of the nature of the acyl group, the reactivity of the oximes tends toward that of the alcoholate ions, and their α-effect disappears. The reason for this is the unfavorable solvation effects of the solvent. Institute of Physical Organic Chemistry and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 2, pp. 86–90, March–April, 1998.     

Modern approaches to the construction of highly efficient nucleophilic systems

In this review we present a summary and correlation of research results obtained in several different approaches aimed at increasing the efficiency and selectivity of nucleophilic reactions, namely the α-effect in aqueous media and specific interactions in nontraditional systems such as “melts” of salts, microemulsions, micelles, and liquid/liquid and liquid/solid interfacial systems. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 35, No. 1, pp. 1–16, January–February, 1999.     

Reactivity of the C-H bond of organic molecules with various structures in hydrogen abstraction by peroxyl radicals

A model of an early transition state with charge transfer is proposed for calculation of the activation parameters of the abstraction of a hydrogen atom by peroxyl radicals from the molecules of organic compounds. It was shown that the compensation effect in this reaction is due to the fact that the change in the preexponential factor is determined by change in the vibrational component of the entropy of activation. L. M. Litvinenko Institute of Physical Chemistry and Coal Chemistry, Academy of Sciences of Ukraine, Donetsk. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 1, pp. 6–11, January–February, 1997.     

Role of dimethylformamide in generating the active form of platinum for catalyzing the synthesis of diaryls from aryl iodides

A mechanism is proposed for the reaction of aryl iodides with platinum(II) tetrachloride complexes in dimethylformamide including formation of PtCl₃(CONMe₂)²⁻ in the first step through activation of a dimethylformamide C−H bond by platinum(II) and subsequent oxidative addition of ArI to this species. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 4, pp. 244–246, July–August, 1998.     

Quasiamorphous state of methane hydrate

It is established experimentally that at temperatures above 0°C formation of methane hydrate starts with the appearance of thin films of this substance on the surface of water; during isothermal storage, the films permeate throughout the whole volume of the sample. The maximal content of methane hydrate is several (volume) per cent. The viscosity of the sample is much lower than that of ice and much higher than that of water. A. A. Galkin Donetsk Physicotechnical Institute, Ukrainian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 39, No. 1, pp. 86–91, January–February, 1998.     

Effect of the structure ofα-substituted styrenes on their electronic structure

The relationship between the experimental ionization potentials and energies of the highest occupied MO was analyzed for various conformations of styrene derivatives using the photoelectron spectra of a series of α-substituted styrenes and quantum chemical calculations of their electronic structure. The characteristics of the HOMO of the planar conformations correlate both with the ionization potentials and the reactivities of these molecules. Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg St., Donetsk, Ukraine 340014, Institute of Technical and Macromolecular Chemistry, Martin Luther University, Halle Wittenberg, Merseburg, Germany D-06217. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 34, No. 1, pp. 36–42, January–February, 1998.     

Adsorption and kinetics of the oxidation of ethylene on PdCl2/SiO2

A new variant of the kinetic distributive method was used to study the kinetics of the oxidation of ethylene by PdCl₂ complexes supported on silica gel taking account of the equilibrium distribution of ethylene between the gas phase, silica gel, and metal complex reaction sites. Mono-, bi-, and polynuclear palladium(II) species are found to participate in the reaction. The Pd^II activity increases with increasing amount of nuclei in the species. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Lyuksemburg ul., Donetsk 83114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 36, No. 4, pp. 243–246, July–August, 2000.     

Isoparametric correlations in reactions of 4-R-N-arylpyridinium salts with arylamines

Isoparametric dependencies of the structure of the reagents (including non-catalytic rate constants, substitution constants σ⁰, basicity constants, and charges at the reaction centers) have been obtained for the reactions between 4-R-N-(2,4-dinitrophenyl)pyridinium salts with arylamines. The electron-acceptor 4-R-substituents studied reduced the positive charge on the reaction center (the α-atom) and the nitrogen atom of the N-arylpyridinium cation. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 R. Luxembourg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 35, No. 4, pp. 231–235, July–August, 1999.