• P Manikyamba

      Articles written in Journal of Chemical Sciences

    • Linear free energy relationship in reactions between diphenyl amine and benzyl bromides

      S Ranga Reddy P Manikyamba

      More Details Abstract Fulltext PDF

      Rate of reaction between benzyl bromide and diphenyl amine is retarded by electron-donating groups and enhanced by electron-withdrawing groups present on the benzene ring of the substrate. Hammett’s reaction constant p of the reaction decreases with increase in temperature according to the equation, ρ =-11.92+ 3.54/T.

      Minimal structural effects observed are attributed to the fact that the isokinetic temperature of the reaction is close to the reaction temperature.

    • Solvent effects in the reaction between piperazine and benzyl bromide

      S Ranga Reddy P Manikyamba

      More Details Abstract Fulltext PDF

      The reaction between piperazine and benzyl bromide was studied conductometrically and the second order rate constants were computed. These rate constants determined in 12 different protic and aprotic solvents indicate that the rate of the reaction is influenced by electrophilicity (𝐸), hydrogen bond donor ability (𝛼) and dipolarity/polarizability ($\pi^\ast$) of the solvent. The LSER derived from the statistical analysis indicates that the transition state is more solvated than the reactants due to hydrogen bond donation and polarizability of the solvent while the reactant is more solvated than the transition state due to electrophilicity of the solvent. Study of the reaction in methanol, dimethyl formamide mixtures suggests that the rate is maximum when dipolar interactions between the two solvents are maximum.

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