synthesis and properties of β-brominated metal complexes of meso-triphenylcorrole

Spectral properties and chemical stability of Mn(III), Mn(IV), Fe(III), Fe(IV), and Cu(III) complexes of β-octabromotriphenylcorrole [(β-Br)₈(ms-Ph)₃Cor], synthesized from β-unsubstituted compounds by their reaction with molecular bromine, were studied. Cyclic voltammetry, electron microscopy, and X-ray spectral microanalysis were used to obtain electrochemical characteristics of metal corroles M(β-Br)₈(ms-Ph)₃Cor and gain insight into the surface texture of active catalysts on the basis of metal corroles. The electron-acceptor β-bromine substitution in the MCor macrocycle shifts the equilibrium in electron-donor solvents to lower oxidation states of the metals and also stabilizes manganese and destabilizes copper complexes in the protondonor medium HOAc-H₂SO₄. The electrocatalytic activity of the complexes in the reduction of molecular oxygen depends on the nature of the ligand and increases in the order Mn ≤ Cu ? Fe in the case of β-octabrominated macrocycles. The character of distribution of active centers on the surface of the catalysts was established for the first time.     

Mechanism of Formation of Tetrahydrofuran in the Catalytic Hydrogenation of Dialkyl Succinates

The kinetics of formation of tetrahydrofuran from dibutyl succinate were studied. The mechanism of catalytic hydrogenation of dialkyl succinates was found to involve consecutive formation of ?-butyrolactone, butane-1,4-diol, and tetrahydrofuran. Parameters of kinetic equations that properly describe the system of concurrent and consecutive reactions were determined.     

Helical magnetocumulative generators with magnetic flux amplification: Comparative advantages of amplification schemes and the operational efficiency of generators with dynamic transformation

The amplification capabilities of two types of helical magnetocumulative generators based on the cascade scheme of magnetic flux amplification, generators with dynamic transformation, and those with transformer coupling between the cascades, are compared analytically and using numerical simulation. A tendency arising in real systems suffering from magnetic flux (energy) losses is studied. The reliability and efficiency of the generators with dynamic transformation can be improved by optimizing the operating modes of the generators and suppressing voltage surges, which are inherent in such devices and arise in the course of flux capture. A method to avoid voltage surges is proposed.     

Kinetic parameters of the electroreduction of oxygen on a graphitized carbon electrode activated by tetrakis(4-methoxyphenyl)porphyrin and its cobalt complexes

Electrochemical and electrocatalytic properties of tetrakis(4-methoxyphenyl)porphyrin, tetrakis(4-methoxyphenyl)porphyrinatocobalt(II), and (tetrakis(4-methoxyphenyl)porphyrinato)chlorocobalt(III) are studied using the method of cyclic voltammetry. The redox-potentials of the electrode processes, the potentials of the half-wave and stationary rate constants for electroreduction of molecular oxygen are determined from an analysis of the voltammetric curves. The cobalt complex is found to be characterized by higher electrocatalytic activity than other analyzed compounds.     

Spectral composition of light scattered in fluid flow around a rotating disk

Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 164–169, May–June, 1991.     

The physicochemical properties of complexones,tetrapyridylporphin derivatives

We synthesized complexones based on tetrapyridylporphin (I), namely, tetra(pyridinium-4-N-carboxymethylene) porphin tetrachloride (II), tetra(pyridinium-4-N-carboxymethylene)porphin tetrabromide (III), complete ethyl ester of (pyridinium-4-N-carboxymethylene)porphin tetrachloride (IV), and tetra(pyridinium- 4-N-methyl)porphin tetraiodide (V). Data on the electronic absorption spectra of the compounds, the enthalpies of their solution in water, and the enthalpies of complex formation with copper(II) and zinc acetates were obtained, and the acid properties of the ligands and their stability under thermooxidative destruction conditions were studied. The conclusion was drawn that the enthalpy of solution of complexone-porphyrins in water was determined by the strength of their crystal lattices and, when different anions (Cl^?, Br^?, and I^?) were present, by the difference of the enthalpies of their hydration. As distinct from Cu²⁺, complex formation between Zn²⁺ and porphyrin ligands occurred with sensible energy expenditures likely caused by the electronic inconsistency between the zinc cation and porphyrin ligands. The stability of water-soluble porphyrins to thermooxidative destruction was limited by temperatures of 200–260°C.     

Preparative synthesis of N-benzyl-tert-butylamine

Russian Journal of Organic Chemistry -     

Steric effects in the catalytic amination of γ-, δ-, and ε-glycols

The amination of butane-1,4-diol, isomeric dipropylene glycols, and cyclohexane-1,4-diyldimethanol in the presence of nickel/copper/chromium catalysts has been studied. The effect of the initial glycol structure on the reaction selectivity has been estimated.     

Electrochemical Properties of a Binuclear Cobalt-Containing Macroheterocycle with an Enlarged Coordination Cavity

The catalytic activity of a binuclear complex of a macroheterocyclic compound (MHCC) containing cobalt(II) and having an enlarged coordination cavity is studied by cyclic voltammetry. Basic features of the electrochemical behavior of MHCC Co₂O₂ in alkaline solution are found. The complex has a higher catalytic activity as compared to cobalt phthalocyanine.