Synthesis, characterization and electrochemistry of unsymmetrical macrocyclic cobalt(ll) complexes derived from bis(benzyl)ethylenediimine

677-680Macrocyclic cobalt(ll) complexes with varying ring sizes (12-14 membered) have been synthesized by using template method with bis(benzil)ethylenediamine precursor. These complexes have been characterized by elemental analyses, conductance, IR and electronic spectra. The spectral data suggest octahedral geometry for all the complexes. Various ligand field parameters have been calculated. The CV results suggest that the cobalt complexes derived from aromatic diamines are reduced at more negative potentials

Synthesis, characterization and electrochemistry of unsymmetrical macrocyclic organocobalt complexes

299-302Macrocyclic cobalt complexes with varying ring sizes have been prepared by template synthesis using bis(benzil)ethylene diimine and different diamines viz. 1,4-diaminobutane, 1,2-diaminobenzene and 3,4-diaminotoluene. These complexes have been alkylated using CH3I and/or C2H5Br in the presence of pyridine and/or imidazole to obtain corresponding macrocyclic organocobalt complexes. The alkylated derivatives have been characterized by elemental analysis, conductivity measurements, magnetic susceptibility measurments, electronic and infrared spectral data. The CV results suggest that all the alkyl cobalt(III) complexes undergo two sequential one electron reductions, Co(III)→<span style="font-size:14.0pt; font-family:HiddenHorzOCR;mso-hansi-font-family:" times="" new="" roman";mso-bidi-font-family:="" hiddenhorzocr;mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:="" ar-sa"=""> Co(II) and Co(II) → <span style="font-size:14.0pt; font-family:" times="" new="" roman";mso-fareast-font-family:"times="" roman";="" mso-ansi-language:en-us;mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Co(I).</span

Organocobalt complexes of diacetylmonoxime buckled with different diamines as 'models' for vitamin B₁₂ derivatives

1312-1316Macrocyclic chlorocobalt complexes have been synthesized using preformed ligands viz. bis(diacetyl monoxime)-1 ,2- phenylenediimine (I) and bis(diacetyl monoxime)-3 ,4-tolylenediimine (II). The chloro derivatives have been alkylated using iodomethane and bromomethane in the presence of pyridine or / and imidazole. The alkyl derivatives have been characterized by elemental analysis, conductivity data, magnetic susceptibility measurements, electronic and infrared spectral data and they are found to be 1:1 electrolytes. Various ligand field parameters like Dqxy, Dqz and Dt have been calculated. Infrared spectra reveal the 'trans effect' in these complexes. Electrochemical behaviour of these complexes has been studied by cyclic voltammetry

A convenient synthesis of tert-butyl ethers under microwave condition

575-578Synthesis of tert-butyl ethers from various alcohols and substituted phenols can be achieved using tert-butyl bromide in the presence of basic lead carbonate as a catalyst under microwave irradiation in absence of solvent. The catalyst is easily recovered via filtration and reused up to three times without appreciable loss of activity

Thermoelastic analysis of a laminated composite skew plate with a circular cutout subjected to linearly varying temperature across the thickness

95-102The behaviour of a laminated composite skew plate with hole subjected to temperature as well as combined temperature and transverse pressure loading has been investigated. A finite element method which works on the basis of three-dimensional theory of elasticity is employed to evaluate the transverse deflection, in-plane stresses and interlaminar stresses. The results obtained by varying the skew angle and the hole diameter are discussed. It has been observed that the magnitude of the stresses and deflection in case of combined loading is more when compared with the respective values in case of pure thermal loading. The magnitudes of the transverse deflection and in-plane stresses for combined loading are observed to be less at higher skew angles, because the distance between opposite sides of the plate decreases with increase in skew angle causing for increase in the stiffness of the plate. The solutions of skew structures considered in the present analysis will be useful for the construction of safe and efficient structures like skew bridges and swept wings of aircraft structures

Synthesis and characterization of cobalt(II) chelates of N,N'-ethylene bis-salicylaldimine and related quadridentate ligands

156-160Cobalt(II) complexes with a series of as many as sixteen SALEN type of quadridentate ligands derived by condensing substituted carbonyls and different diamines have been synthesized and characterized by IR, 1N NMR, molar conductivity. magnetic susceptibility measurements and electronic spectral data. Subnormal magnetic moment values infer the presence of dimeric structure for the present complexes. However, electronic spectral data suggest a square planar structure in solution. possibly due to the monomeric structure. Infrared spectral data suggest the bonding of ligands through two ortho phenolic oxygen and two azomethine nitrogen atoms. The electrochemical behaviour of these complexes has been studied by cyclic voltammetry. Additional phenolic groups present in these complexes are useful for the facile synthesis of polymer supported cobalt complexes.</span

Determination of quantum yield for the photolysis of aqueous solution of chloramine-B

613-615Photolysis of aqueous solution of chloramine-B (0.01-0.0002mol dm-3) is studied with a UV light source and the products have been identified. A suitable photolytic mechanism is suggested based on the observed results. The photolytic decomposition obeys first order kinetics. Quantum yield for the photolysis of chloramine-B is reported

Determination of quantum yield for the photolysis of aqueous solution of chloramine-B

Photolysis of aqueous solution of chloramine-B (0.01-0.0002mol dm-3) is studied with a UV light source and the products have been identified. A suitable photolytic mechanism is suggested based on the observed results. The photolytic decomposition obeys first order kinetics. Quantum yield for the photolysis of chloramine-B is reported

Oxidimetric determination of isoniazid and amino acids with bromamine-B in buffer medium

Bromamine-B oxidises isoniazid, glutathione, glycine, leucine, isoleucine, valine, alanine, phenylalanine, threonine and glutamine stoichiometrically in pH 5 (pH 6 for isoleucine and threonine) acetate buffer medium with a four-electron change (six-electron change for glycine and ten-electron change for glutathione). Back-titration procedures have been developed for the determination of isoniazid and amino acids. The products have been identified. The method has been successfully employed for the determination of isoniazid in pharmaceutical preparations and also for the estimation of metal complexes of glutathione and metal salts of glycine and alanine

Kinetics and mechanism of oxidation of L-isoleucine and L-ornithine hydrochloride by sodium N-bromobenzenesulphonamide in perchloric acid medium

Kinetic studies of the oxidation of L-isoleucine (ISL) and L-ornithine hydrochloride (ORH) by sodium N-bromobenzenesulphonamide (bromamine-B or BAB) were studied in aqueous perchloric acid medium. The rate shows first-order dependence on both [BAB](0) and [amino acid](0) and inverse first-order dependence on [H+] for ISL and first-order dependence on [H+] for ORE. The rate of reaction decreased with decreases in the dielectric constant of the medium. The addition of benzenesulphonamide (BSA), which is one of the reaction products, had no significant effect on the reaction rate. The rate remained unchanged with the variation in the ionic strength of the medium for ISL, whereas the rate decreased with increases in the ionic strength of the medium for ORR Isovaleronitrile and 3-(methylamino)propionitrile were identified as the products. Thermodynamic parameters were computed by studying the reactions at different temperatures (298-316 K). The rate laws derived are in excellent agreement with the experimental results. Plausible mechanisms are suggested