Electrochemical activation of freons using electron transfer mediators

This overview discusses the electrochemical activation of freons CF₂ClCFCl₂ (CFC113), CF₃Br (FC13B1), and CF₂Cl₂ (CFC12) using various electron transfer mediators: complex nickel(ii) compounds with nitrogen-containing tetradentate ligands and bipyridyl, aromatic derivatives (perylene, p-dicyanobenzene, Å-azobenzene, and others), and sulfur dioxide. A possibility was shown of the homogeneous catalytic activation of freons by two mutually supplementing electron transfer mediators: methylviologen—SO₂ and I₂—SO₂. The involvement of freons by the electron transfer mediators into the syntheses of valuable organic products under mild conditions was demonstrated for several examples.     

Electrochemical carboxylation of fluorocontaining imines with preparation of fluorinated N-phenylphenylglycines

A possibility of obtaining fluorine-containing N-phenylphenylglycine derivatives at yields of up to 85% via the electrochemical carboxylation of corresponding benzalanilines was shown. The influence of imine's electron structure, the nature of supporting electrolyte and cathodic material on such processes is examined. It was found, that increasing electron accepting ability of the substituents in benzylidene and aniline fragments of the imine molecule lead to decrease of amino acid yields. The dependence of the N-phenyl-p-fluorophenylglycine yield on the cathode material (Zn, GC, Cu, Ag, Pt) and on the nature of the supporting electrolytes (Bu₄NBr, Et₄NBr, Et₄NClO₄, PhCH₂Me₃NClO₄, LiBF₄, LiClO₄, NaBF₄ and KBF₄) was investigated. The highest amino acid yields were obtained at cathodes (GC and Zn) that do not exhibit specific adsorption of fluorine-containing imines, as well as in the presence of background salts (Alk₄NBr) whose cations do not show tendency to strong ion pairing with anion radicals formed by the electrochemical activation of the imines.     

Electrocatalytic properties of nanocomposites based on conducting polymers and titanium dioxide in oxygen reduction process

Electrochemical characteristics and electrocatalytic properties in the oxygen reduction reaction are studied on hybrid nanocomposites based on conducting polymers (polyaniline, polypyrrol) doped with phosphomolybdic acid (PMA), and TiO₂ and also their bifunctional analogs containing up to 5 wt % of nanosize platinum. It is found that the obtained nanocomposites in 0.5 M H₂SO₄ are capable of reversible electro-chemical redox transitions (in the range of potentials from ?0.6 to 1.0 V vs. Ag/AgCl), in which the main contribution is provided by the corresponding conducting polymer and dopant (PMA). It is shown that activity of the studied nanocomposites in the oxygen reduction reaction is caused by the joint catalytic effect of all their components: the polymer, TiO₂, H₃PMo₁₂O₄0, Pt.