Oxidation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) by Alcaligenes eutrophus A5

Previous studies demonstrated that Alcaligenes eutrophus A5 transforms 1,1, 1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) to 4-chlorobenzoate via a m eta-ring fission product. The initial reactions could be catalyzed by eithe r monooxygenase or dioxygenase enzymes. In the present study, a transient i ntermediate that accumulated during the transformation of DDT by the biphen yl-grown cells was identified as 1,1,1-trichloro-2-(4-chlorophenyl-2,3-dihy dro-4,6-cyclohexadiene)-2-(4'-chlorophenyl)ethane (DDT-2,3-dihydrodiol) on the basis of mass spectral analysis after n-butylboronic acid derivatizatio n. The dihydrodiol undergoes a characteristic acid-catalyzed dehydration to produce phenols. H-1-NMR indicated a cis-relative stereochemistry. The res ults indicate that the biphenyl dioxygenase from A. eutrophus A5 catalyzes the dihydroxylation of DDT at the unsubstituted carbons on the aromatic rin g to produce DDT-2,3-dihydrodiol.