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The magnetic circular dichroism (MCD) of benzene and 27 derivatives through the absorption region 1850-3000 Á have been measured. Two different electronic transitions in the region 2000-2300 Á (generally assigned to the benzene 1Biu upper state) were observed in some of the compounds. The theory developed by Sklar, Platt, and Petruska for predicting the intensity of the benzene 1Aig -1B2U electronic transition is adapted to correlate the sign and intensity of the substituted benzene MCD in this region. The method predicts the correct MCD sign and gives approximate estimates of the magnitude of the

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The linear relation between the magnetic circular dichroism (benzene 'Aig -'B2-transition) of monosubstituted and 1,4-disubstituted benzenes and the substituent constants a and OfR are compared. In all cases, better linear correlations were found between the magnetic circular dichroism and aR. (benzene 'Aig --lB2, transition) data of monosubstituted and 1,4-disubstituted benzenes with both ar and aR. The experimental procedure and equipment are exactly the same as those described in the previous paper (2) and will not be described here. We have measured the MCD of X-C6H4-I (X=H, CH3, Cl, Br, I, OH, NH2, NO2, or CO2H), X-C6H4-NO2 (X=H, CH3, F, Cl, Br, I, NH2, NO2, or CO2H), and X-C6H4-CO2H (X=H, CH3, F, Cl, Br, I, OH, NH2, CN, or NO2) in methanol solutions. Data of the MCD of monosubstituted benzenes are taken from the previous paper (2).In Table 1

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