STUDIES ON PATHWAYS OF RING-OPENING OF BENZENE IN A FENTON SYSTEM

Ring-opened products of benzene metabolism have been postulated to pla y a role in hematotoxicity and leukemogenesis. The reaction of benzene in the Fenton system was reexamined to determine the presence of comp ounds which might serve as intermediates in the formation of trans,tra ns-muconaldehyde (MUG), a microsomal hematotoxic metabolite of benzene . Benzene dihydrodiol (DHD) was found in this system based on coelutio n with authentic standard, ultraviolet (UV) absorption characteristics , and molecular weight. Incubation of DHD in the Fenton system resulte d in the formation of phenol (PH), catechol (CAT), and products which reacted with thiobarbituric acid to form chromogens absorbing at 495 n m and 532 nm, consistent with products containing an alpha,beta-unsatu rated aldehyde group. However, muconaldehyde was not detected in the F enton system incubated with DHD, indicating that MUC is not formed via ring opening of DHD. When benzene was incubated in the Fenton system, MUG, cis,trans-muconaldehyde, PH, hydroquinone (HQ), and CAT were ide ntified. Identification of cis,transmuconaldehyde, an isomer which can quickly rearrange to MUG, suggests that cis,cis-muconaldehyde is orig inally formed from benzene and converted to cis,trans- and then trans, trans-muconaldehyde.