Benzene oxide Benzene oxide (C6H6O) exists as an
equilibrium mixture with the seven-membered
ring oxepin, which has three
double bonds. The arene oxide and oxepin are
valence isomers. The equilibrium proceeds via disrotatory 6π ring closing and opening. The arene oxide can rearrange to give the diene-ketone via the
NIH shift. This process is the initial step in the detoxification of benzene by the
cytochrome P450.
Benzene oxide can also hydrate to give
dihydroxydihydrobenzene. The hydration is catalyzed by
epoxide hydrolase enzymes. Dehydration of this diols, which is driven by rearomatization, gives phenol.
Naphthalene derivatives Naphthalene-1,2-oxide forms from
naphthalene. It hydrates to give 1,2-dihydroxydihydronaphthalene. The hydration is again catalyzed by
epoxide hydrolase enzymes. Dehydration of this diol gives
1-naphthol. Oxidation of 1,2-dihydroxydihydronaphthalene, catalyzed by dihydrodiol dehydrogenase, gives the
1,2-naphthoquinone. The oxide derived from 1-
naphthol results in 1,4-naphthoquinone. These conversions are relevant to the
biodegradation of naphthalenes. ==References==