Proceedings of the Indian Academy of Sciences. Section A: Chemical Sciences

Rao, G; Rajaram, J; Rathnamala, S; Sivaramakrishnan, R

doi: 10.1007/BF03046875pmid: N/A

Hydrogenation of someα, β-unsaturated carbonyl compounds using potassium pentacyanocobaltate (II), K3Co(CN)5, as a homogeneous catalyst has been investigated. Thus, hydrogenation of 1-carvone (I), mesityl oxide (4), 2-cyclohexenone (8) and benzalacetone (6) afforded the corresponding dihydrocompounds. Hydrogenation ofβ-ionone (10) afforded a mixture of theα, β-dihydrocompounds (14) and (15). In all these cases, it was observed that the reaction proceeded to completion only in the presence of added base. Hydrogenation of 5α-androst-l-en-17β-ol-3-one acetate (19) afforded the saturated compound, 5α-androst-17β-ol-3-one (20) in 60% yield. It was found that other steroid enones and dienones were not reduced by this catalyst system.

Manjula, G; Ramakrishnan, C; Sarathy, K

doi: 10.1007/BF03046876pmid: N/A

A study on the conformational aspects of cyclo-hexaglycyl having inversion symmetry has been made. The cyclic backbone has been assumed to have two internal 4→1 types of NH... O hydrogen bonds. This molecule has been found to take up two types of conformations designated asA* andB* having nearly the same energy values. The theoretical conformations have been compared with the conformations of cyclohexaglycyl hemihydrate observed in the crystal structure. Two molecules with an approximate inversion symmetry are close to the conformation of the typeB* and two other molecules with exact inversino symmetry correspond nearly to the typesB* andA*. comparison with the theoretically possible conformations of cyclohexaglycyl molecule with 2-fold symmetry has been made. The preference of inversion symmetry and preferred ranges ofψ for glycyl molecules is discussed.

Palanna, O; Mohan, A; Biswas, A

doi: 10.1007/BF03046877pmid: N/A

The electrical and magnetic properties of vanadates of the general formula (MO) n .V2O5, where M=Mn, Co, Ni, Cu and Zn, andn=1, 2 and 3, are discussed. Conduction in these materials occurs due to small deviations from the stoichiometric composition in the form of anion-(n-type) or cation—(p-type) vacancies. The mechanism of electrical transport is of a thermally activated hopping of charge carriers on equivalent cation lattice sites. It has been found that the meta vanadates (n=1) are alln-type while the pyro—(n=2) and ortho—(n=3) compounds of Mn, Co and Ni arep-type; but Cu and Zn analogues remainn-type only.

Jayathirtha, Y; Krishnan, V

doi: 10.1007/BF03046878pmid: N/A

The interaction of six macrocyclic polyethers with 1, 3, 5-trinitrobenzene has been studied by spectroscopic methods. The association constants have been evaluated by1HMR chemical shift method. There is evidence that major contribution to the interaction isvia n andπ electrons. The donor strengths of the polyethers have been evaluated.

Sudha, B; Dixit, N; Patel, C

doi: 10.1007/BF03046879pmid: N/A

Preparation and structural characterization of palladium (II) complexes of ligands III-V and copper (II) complexes of III are reported. The elemental analyses of the complexes show that the metal: ligand ratio is 1:2. The electrical conductance in acetone shows the non-electrolytic nature of the complexes. The diamagnetic character suggests a gross square-planar geometry for the palladium (II) complexes. Copper (II) complexes are paramagnetic with¼eff.∼1·90 B.M. Spectral data suggest that in all the complexes the ligand coordinates to the metal (II) symmetrically through isonitroso-nitrogen and imine-nitrogen, forming a five membered chelate ring. Amine-exchange reactions of the complexes are discussed and compared on the basis of their structures.

Rao, V; Murty, D; Murty, A

doi: 10.1007/BF03046880pmid: N/A

Methods for the determination of iron (III) as thiocyanate complex in the presence of neutral donors like isoquinoline and antipyrine have been developed. The two methods are of equal sensitivity (ε=18,000±100 lit. mole−1 cm−1) but operate at widely different hydrogen ion concentrations ranging from 10−5 N(pH 5·0) to 7N. The interference of various foreign substances has been studied in the two methods. The application of these methods in the analysis of alloys and commercial HCl for iron has been explored and the composition of the extracting species established.

Varughese, K; Radhakrishnan, T

doi: 10.1007/BF03046881pmid: N/A

In neutral thiocyanate medium at low temperatures (0–5°C) cobaltous ion produced an anomalous double wave of nearly equal height. This behaviour was ascribed by earlier workers to a stepwise reduction of cobaltous ion in this medium. A study of the effects of temperature and height of the mercury column as well as the influence of the concentrations of cobalt and thiocyanate on the waves showed that the processes were controlled by chemical reaction and adsorption. It has been concluded that the first wave is a surface kinetic wave resulting from the reduction of [Co(H2O)4(SCN)2] and the second step is a post-adsorption wave brought about by the adsorption of [Co(H2O)5SCN]+ species on the electrode.

Varughese, K; Radhakrishnan, T

doi: 10.1007/BF03046882pmid: N/A

The polarographic behaviour of cobalt (II) in water and 50% methanol in the presence of various supporting electrolytes has been studied. The kinetic parameters and activation energy for the electrode process have been evaluated and compared. The results have been discussed on the basis of selective hydration of cobaltous ion at the electrode surface.

Shelke, D; Jahagirdar, D

doi: 10.1007/BF03046883pmid: N/A

The interactions of uranyl and copper ions with dicarboxylic acids such as succinic, itaconic, adipic and malonic acids have been investigated in 20, 40, 60 and 80% (v/v) dioxane-water mixtures at 30°C and 0·06 ionic strength by Calvin-Bjerrum titration technique. UO 2 2+ , Cu2+ form only 1:1 complexes with succinic, itaconic and adipic acids and both 1:1 and 1:2 with malonic acid in the pH range 2·5–5. The plots of pK/log K vs mole fraction gave linear while those with 1/D gave non-linear. The complexation equilibria:[Figure not available: see fulltext.] are proposed. The radius of anionic ligand is calculated from Born equation and attempts are made to understand the medium effect on the pK values.