Abstract

M. Krishna Pillay* and M. Seenimubarak

Some of the literature data are interpreted In favour of the newer phenomena of Steric Enhancement of Resonance (SBR). The mcsomeric moment (Δμ) of 2,4-dinitro-anisolc is very significant, 0.87 D which can only be accounted due to the extended conjugation between the -OCH3 group and 4-NO2 group. The spin-spin coupling constants between methyl protons (of-OCH3) and the benzene ring proton (JOHCH3=5J) of suitably Subsituted anisoles arc found to support SER. From this study one may be convinced that an ortho subsituent does not sterically inhibit methoxyl group from conjugating with an electron-withdrawing group in 4-position rather enhance the conjugative interaction.

Enhancement; Resonance; (JOHCH3=5J)

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