Phenanthrene, oxidation

Dihydro-9,10-epoxyphenanthrene and related arene oxides are of considerable interest as carcinogens formed by polycyclic aromatic hydrocarbons in vivo.45 Phenanthrene oxide does not isomerize to the corresponding dibenzoxepin under thermal conditions. Photolysis of... 

Moen MA, KE Hammel (1994) Lipid peroxidation by the manganese peroxidase of Phanerochaete chrysosporium is the basis for phenanthrene oxidation by the intact fungus. Appl Environ Microbiol 60 1956-1961. 

This section is dedicated to arene oxides of bicyclic and tricyclic arenes (e.g., naphthalene, anthracene, and phenanthrene oxides), whereas higher arenes and particularly benzo[a]pyrene (one of the most toxic and intensively investigated PAHs) are examined in Sect. 10.4.4. 

Turning to enzymatic hydration, we see from the data in Table 10.1 that phenanthrene 9,10-oxide Fig. 10.10, 10.29) is an excellent substrate for epoxide hydrolase. Comparison of enzymatic hydration of the three isomeric phenanthrene oxides shows that the Vmax with the 9,10-oxide is greater than with the 1,2- or the 3,4-oxide the affinity was higher as well, as assessed by the tenfold lower Km value [90]. Furthermore, phenanthrene 9,10-oxide has a plane of symmetry and is, thus, an achiral molecule, but hydration gives rise to a chiral metabolite with high product enantioselectivity. Indeed, nucleophilic attack by epoxide hydrolase occurs at C(9) with inversion of configuration i.e., from below the oxirane ring as shown in Fig. 10.10) to yield the C-H9.S, 10.S )-9,10-dihydro-9,10-diol (10.30) [91],... 

A parallel was drawn between stable ion and AMI studies of methylphenanthrenes and solvolytic studies of K-region and non-K-region phenanthrene oxides. The carbocation formed by opening of the 1,2-epoxide closely resembled the 2-methylphenanthrene cation (and 7H ), and the regiochemistry of phenol formation (1-phenanthrol) could be understood. Similarly, phenanthrenium cations derived from the 3-methyl and dimethylated compounds served as models for carbo-cations formed by solvolysis of phenanthrene-3,4-epoxide (formation of 4-phenanthrol following hydride shift). 

Included in this section are oxidations of benzene and phenyl rings, and in general the oxidation of aromatic and polycyclic aromatic compounds. The main catalyst for this type of reaction is RuO. The earliest example was the use of stoich. RuOy CCI4 for phenanthrene oxidation [239], while the first catalytic reagent was RuO / aq. Na(I04)/acetone for oxidation of pyrene [240]. Another early example was the conversion of diketo compounds to the nor-diketo acids, with concomitant destruction of the two phenyl rings by RuO /aq. NallO l/acetone (Fig. 3.18, 3.2.2.1) [206]. 

Comparison of the reactivities of benzene oxides, naphthalene oxides, phenanthrene oxides, and arene oxides derived from benzo [a] pyrene and 7,12-dimethylbenz[a] anthracene with hepatic glutathione S-epoxide transferase showed that benzene oxides without electron-withdrawing groups are poor substrates as also are polycyclic arene oxides. Only naphthalene oxide was a good substrate. 

Other phenanthrenoids include the phenanthrene oxidative derivatives, hydrogenated derivatives and hybrids of phenanthrenes. Fig. (21). 

The presence of benzoic acid or of diphenic acid, formed in the wet oxidation of plienanthraquinone, has not been reported in the products of phenanthrene oxidation in the vapor phase. A naphthalic acid has been found and the presence of quinones established in the products.11, b Mechanism for this oxidation cannot be postulated because of the present lack of data. 

When deuterated phenanthrene oxide undergoes an epoxide rearrangement in water, 81% of the deuterium is retained in the product. 

The K-region phenanthrene oxide (68) undergoes photochemical ring-enlargement to (69) via the singlet excited state. A similar photochemical rearrangement for the K-region 3,4-epoxy-3,4-dihydropyrene was also reported. 

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