• V R Vijayaraghavan

      Articles written in Journal of Chemical Sciences

    • Kinetics of oxidation of nickel(II) aza macrocycles by peroxydisulphate in aqueous media

      J Lalitham V R Vijayaraghavan

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      The kinetics of the oxidation of nickel (II) hexaaza and nickel (II) pentaaza macrocycles by the peroxydisulphate anion, S2O82−, were studied in aqueous media. Effect of pH on reaction rate was also studied. The rate increases with increase of S2O82− concentration. Rates are almost independent of acid betweenpH 4 and 2, giving overall a relatively simple second-order rate law followed by oxidation within the ion pair solvent shell. Using rate =+1/2 d[Ni(L)3+]/dt =k[Ni(L)2+][S2O82−], oxidation rate constants were determined.

    • Reduction of CO2 by nickel (II) macrocycle catalyst at HMDE

      M Aulice Scibioh P V Ragini S Rani V R Vijayaraghavan B Viswanathan

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      With the aim of finding a suitable electrocatalyst for the efficient reduction of carbon dioxide, the electrochemistry of nickel (II) complex of 1,3,6,9,11,14-hexaazatricyclo [12·2·1·1] octadecane was studied using cyclic voltammetry (CV) and controlled-potential electrolysis (CPE) techniques in the presence and absence of CO2 in 100% H2O, CH3CN-H2O mixtures (20–100%) and DMF-H2O (70–100%) mixtures. The efficiency of this process is determined using the coulometry technique. CO is the major product in the gaseous phase and HCOOH the sole product formed in the solution phase.

    • Isopropylation of benzene with 2-propanol over substituted large pore aluminophosphate-based molecular sieves

      K Joseph Antony Raj V R Vijayaraghavan

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      Large pore aluminophosphate-based molecular sieves like AlPO4-5, MAPO-5, MnAPO-5 and ZAPO-5 were synthesised hydrothermally using triethylamine as a structure directing agent. These materials were characterised by X-ray diffraction (XRD),27A1 and31P MAS-NMR, ICP-MS,n-butylamine-TPD, BET and SEM. The catalytic performance of these materials was tested for isopropylation of benzene with 2-propanol at 250, 300, 350 and 400°C. The products were cumene,p-DIPB (p-diisopropylbenzene) andm-DIPB (m-diisopropylbenzene). MnAPO-5 was found to be more active than the other catalysts. Maximum conversion (20%) was noted at 350°C over MnAPO-5. The selectivity to DIPB was found to decrease with time on stream but the selectivity to cumene showed an increase after 3 h of time on stream

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