N. I. Maksimyuk

Electrochemical reduction and oxidation of 3,4-disubstituted 1,2,5-thiadiazoles

The electron-acceptor nitrogen and sulfur atoms in 3,4-disubstituted 1,2,5-thiadiazoles are responsible for much decreased reduction potentials and much increased oxidation potentials of these compounds compared with the corresponding carbocyclic derivatives. The thiadiazole ring is resistant to oxidation, and the reversible electron transfer gives rise to fairly stable radical cations. Reductive stability of the heterocycle depends on the nature of its substituents and on the medium: When nucleofuge substituents are present, two-electron transfer in aprotic media results in heteroring opening with iminonitrile formation, whereas in the presence of two readily leaving groups, the electron transfer induces cleavage of the complete heteroring into inorganic anions.

Complexes of rhodium carbonylchloride and phosphorus(iii) cyanides in mediated electrochemical reduction of 2-carbomethoxy-2-methyl-1,1-dichlorocyclopropane

AbstractElectrochemical reduction of the complexes Rh(CO)ClL2 [L = (EtO)2PCN (1), Ph2PCN (2)] and Rh2(CO)4L [L = P(CN)3 (3),

THE KINETICS OF THE HOMOGENEOUS REDUCTION OF ORGANOBROMO AND ORGANOCHLORO COMPOUNDS BY ANTHRACENE RADICAL ANIONS IN THE PRESENCE OF NIII AND COII IONS

Ph\begin{array}{*{20}c} P \\ | \\ {CN} \\ \end{array} ---\begin{array}{*{20}c} P \\ | \\ {CN} \\ \end{array} Ph

Heterogeneous and homogeneous reduction of benzyl phenyl ether

(4)] and their catalytic properties in electrochemical reduction of 2-carbomethoxy-2-methyl-1,1-dichloro-cyclopropane were studied. The catalytic electroreduction of a substrate at the reduction potentials of the central ion was developed for complexes2–4. This process is accelerated substantially for complexes2 and3 in the presence of anthracene.

Electrochemical Reduction of 1,4-Disubstituted Phthalazines

The character of the first stage of reduction of 5-X-5-nitro-1,3-dioxanes 1—10 and 2-X-2-nitro-1,3-propanediols 11 and 12 is independent of the nature of halogen (X = Br, Cl) and substituents in position 2 of the dioxane cycle. The transfer of two electrons to a molecule of compound 1—12 is accompanied by the anionoid elimination of halogen and formation of the anion of nitronic acid. The high mobility of halogen is mainly due to the acceptor nitro group capable of further transformations in the α-position to halogen. The direction of further reduction involving the electron transfer to electrochemically active groups in the aromatic fragment of the molecule is determined by the nature of these groups. Chloro-, bromo-, and iodophenyl-substituted derivatives 4, 5, and 8—10 are reduced as typical halobenzenes. In the case of nitrophenyl-substituted compounds 3 and 7, the dioxane cycle opens to form dianions of p- and m-nitrobenzaldehydes along with the reduction of the nitroso group through the stages of formation of the radical anion and radical anion of the nitroso group. The radical anions of the nitro and nitroso derivatives were identified by ESR.

Kinetics of electrochemical reduction of 2-carbomethoxy-1,1-dichloro-2-methylcyclopropane by the double mediator system anthracene-PtII, PdII, and NiII complexes of cyclic aminomethylphosphines

The effect of NiII and CoII on the kinetics of the homogeneous reduction of some aromatic, aliphatic, and cyclic organobromo and organochloro compounds by anthracene radical anions has been studied by the polarographic method. It has been shown that the catalytic action of the metal ions increases as the reducibility of the organohalide compounds decreases.

Kinetics of the mediatory reduction ofgem-dichlorocyclopropanes

The electrochemical reduction of 1,1-dihalo-2-R-2-methylcyclopropanes was studied by polarography and preparative electrolysis. A mixture of stereoisomeric monoboro- and monochlorocyclopropanes was obtained with preparative yield of 60–70% in preparative electroreduction in methanol against a background of 0.1 M LiClO4. In the case of bromine derivatives of cyclopropanes (except when R = CN) an effect was found on the part of the current density on the ratio of cis and trans isomers, which was interpreted as a change, in dependence on current density, of the contributions of the reactions of reduction of the starting compounds (SN2 mechanism) and ionic pairs (SN1 mechanism). The effect of the solvent (CHCl3, DMF, DMSO, MeOH) and background salt (LiClO4, Et4NBr) on the ratio of stereoisomers is in agreement with this interpretation.

Role of Ni(II) and Co(II) ions in the mediated reduction of gem-dichlorocyclopropanes

By analyzing the kinetics of heterogeneous (electrode) and homogeneous reduction for benzyl phenyl ether it was found that toluene and phenol are formed via the transfer of two electrons and the breaking of the PhO-Bz bond. It was shown that electron transfer constitutes the slow stage in heterogeneous and homogeneous reduction. The homogeneous transfer coefficient was approximately 0.5, which represents a significant difference from the heterogeneous value.