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    • Keywords


      α,β-unsaturated ketones; split in the C=O bands; rotational isomers; polarity of the conformers; π-electron repulsions

    • Abstract


      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.

    • Author Affiliations


      G Venkateshwarlu1 B Subrahmanyam1

      1. Department of Chemistry, Osmania University, Hyderabad - 500 007, India
    • Dates

  • Journal of Chemical Sciences | News

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