AB INITIO COMPUTATIONS OF CHRYSENE AND 5-METHYLCHRYSENE
(艹屈)和5-甲基(艹屈)的ab initio计算

The substitution of a methyl group on a nonbenzo bay-region site of a polycyclic aromatic hydrocarbon can greatly enhance its carcinogenic activity. Ab initio computations of chrysene and 5-methylchrysene show that the electron properties of C1-C2 bond of 5-methylchrysene are favorable for an electrophilic reaction. Electron density maps indicate that electron density around C1-C2 bond of 5-methylchrysene is is higher than that of the similar part of chrysene, which also shows that the C1-C2 boud of 5-methylchrysene attacked by electrophilic agent more easily. Therefore, 5-methylchrysene is easily oxidized to form an epoxide in C1-C2 bond and to form an ultimate carcinogen during metabolism.These effects result in much higher carcinogenicity of 5-methylchrysene than that of chrysene.