Abstract
The theory of hyperconjugation has been extended and applied to computations of the electronic structures of methyl and ethylsubstituted acetylenes and benzenes using the empirical LCAO MO method not including the overlap integrals. The common empirical parameters introduced from experimental aspects were used consistently through the calculations. Charge distributions of the π-electrons, bond orders, resonance moments, relative shifts of near ultraviolet absorption spectra and oscillator strengths were calculated, and fairly satisfactory results, compared with the observed values, were obtained. Because of the lack of appropriate absorption data, the near ultraviolet absorption spectra of alkylbenzenes in normal hexane were obtained. The calculations show that when the methyl group is substituted for a hydrogen atom of the methyl group, the hyperconjugative effect is recognized as same as before.

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