• G Venkateshwarlu

      Articles written in Journal of Chemical Sciences

    • Conformations of dibenzylideneacetone: An IR spectroscopic study

      G Venkateshwarlu B Subrahmanyam

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      The conformational analysis of dibenzylideneacetone has been carried out using IR spectroscopy. Appearance of a triplet C=O band is attributed to the coexistence of three conformers viz s-cis, cis, s-cis, trans and nonplanar s-trans, trans in contrast to the earlier findings which showed the existence of only two conformers. The relative proportions of the conformers are in the order s-cis, trans> nonplanar s-trans, trans> s-cis, cis in less polar solvents and nonplanar s-trans, trans> s-cis, trans> s-cis, cis in more polar solvents.

    • Conformations ofαchloroacetanilides: An IR spectroscopic study

      G Venkateshwarlu P Padmavathi Reddy B Subrahmanyam

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      The conformational analyses of α-mono, α-di and α-trichloroacetanilides have been carried out using IR spectroscopy. α-Monochloro, dichloro and trichloroacetanilides were found to exist in only one conformation in CH2Cl2 and CHC13. The existence of all these anilides in single conformation is due to intramolecular H-bond formation between N−H and Cl.

      In CH3CN, the broadening of C–0 bands of monochloroacetanilides and their bifurcation in α-dichloroacetanilides indicated the existence of two rotamers due to the breaking of chelation by the solvent.

    • Conformations of α,β-unsaturated ketones: An IR spectroscopic study

      G Venkateshwarlu B Subrahmanyam

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      The conformational analyses of substituted methyl styryl ketones and phenyl styryl ketones have been carried out using IR spectroscopy. The split in the C=O bands of these compounds is attributed to the existence of two conformations, viz.s-cis ands-trans, in equilibrium. The methyl styryl ketones exist predominantly in thes-trans form whereas phenyl styryl ketones exist in thes-cis form. In all the ketones studied the proportion of thes-trans form increases with increase in the polarity of the solvent while that of thes-cis form decreases. This shows that thes-trans form is more polar than thes-cis. The field effects between the C=O and C=C groups are found to be electrostatic repulsions which play a dominant role in the determination of the relative stabilities of thes-cis ands-trans forms over the steric effects and the electrostatic attractions between the carbonyl oxygen and the β-carbon.

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