2-Hydroxybiphenylene has been prepared by Baeyer-Villiger oxidation of the corresponding 2-benzoyl compound, itself made by direct substitution in biphenylene. The hydroxy-compound couples with diazonium salts in position 3, as predicted by Longuet-Higgins. Oxidation of the hydroxycompound with potassium nitrosodisulphonate gives biphenylene-2,3quinone (V) which is more conveniently prepared through the azophenol (III). This quinone, the first to be prepared in the biphenylene series, is remarkably stable. Under the conditions of Thiele acetylation, it behaves anomalously and yields a tetra-acetate (VI).STUDIES of hydroxybiphenylenes and biphenylenequinones have been hampered by the inaccessibility of the hydroxy-compounds. Reaction of biphenylene with lead tetraacetate followed by hydrolysis gives 2-hydroxybiphenylene in 1.5% yield; the same compound can be made by acid hydrolysis of its methyl ether, but the latter also is difficultly ac~essible.~ 2-Acetylbiphenylene did not undergo the Baeyer-Villiger reaction and attempts to cleave the ether groups of 2,7-dimethoxybiphenylene have been unsuccessful.* We have now found that 2-benzoylbiphenylene is readily converted into 2-benzoyloxy-and thence into 2-hydroxy-biphenylene. Some reactions of this compound, including its conversion into biphenylene-2,3-quinone, are described below.Biphenylene (I; R = H) reacted with benzoyl chloride in the presence of aluminium chloride to give 2-benzoylbiphenylene (I; R = Bz), the orientation of which was proved by conversion of the corresponding oxime into 2-benzamidobiphenylene (I; R = NHBz) by a Beckmann rearrangement. When the ketone (I; R = Bz) was treated with peracetic acid in acetic acid containing sulphuric acid (conditions critical), it gave the benzoate (I; R = OBz) which on alkaline hydrolysis yielded 2-hydroxybiphenylene (11) in ca. 23% overall yield from biphenylene.The phenol (11) coupled readily with diazonium salts to give deep red azo-compounds

t ‐Butyl carbazate solvent: 430 ml. (422 g., 5.33 moles) of pyridine reactant: 508 ml. (395 g., 5.33 moles) of t ‐butyl alcohol reactant: 536 g. (4.85 moles) of methyl chlorothiolformate intermediate: 500 g. (3.47 moles) of t ‐butyl S‐methylthiolcarbonate solvent: 50‐50 mixture of low‐ (b.p. 30–60°) and high‐boiling (b.p. 60–70°) ligroin reactant: 430 g. (3.33 moles) of quinoline reactant: 520 g. (3.32 moles) of phenyl chloroformate intermediate: 388.4 g. (2.0 moles) of phenyl t ‐butyl carbonate solvent: petroleum ether product: t ‐Butyl carbazate product: bibenzyl

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