STERIC INHIBITION OF RESONANCE BY ORTHO CHLORINE ATOMS IN STYRENES AND BENZENE CARBOXYLIC ACIDS, SPECTRAL EVIDENCE.
Technical scientific note,
CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS BARCELONA (SPAIN) DEPARTAMENTO DE QUIMICA ORGANICA
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The ultra-violet spectra of alpha,beta,beta,2,3,4,5-heptachlorostyrene I, perchlorostyrene II, 2,3,4,5-tetrachlorobenzoic acid, 2,3,5,6-tetrachlorobenzoic acid, pentachlorobenzoic acid, 2,5-dichloroterephthalic acid, and tetrachloroterephthalic acid, are reported and interpreted. Strong steric inhibition of resonance makes the spectra of the derivatives the side chain of which is flanked by two ortho chlorine atoms to appear almost, or even quite, indistinguishable from those of chlorinated alkylbenzenes of comparable degree of substitution. Also, it is shown that the inhibition of resonance is somewhat relieved in the monoortho chlorinated derivatives. The spectra of I and II are compared respectively with those of the trans forms of alpha,2,3,4,5,alpha,2,3,4,5-decachlorostilbene and perchlorostilbene. Author
- Organic Chemistry