Dihydroxybenzenes Catechols and their Derivatives

There has been considerable interest in the hydroxylation of phenol through a variety of approaches. The oxygenation of phenol in acetonitrile in the presence of cuprous chloride in catalytic quantities gave, after work-up by acidification, catechol in yields of 70-90% (ref.1) by way of a copper (II) intermediate. 

By the use of hydrogen peroxide a similar transformation has been effected (ref.2). 

2-Cyclohexane derivatives have been employed as in the case of 

3-phenylcyclohexane-1,2-dione which by refluxing with 4-toluenesulphonyl chloride, potassium carbonate and a small proportion of azoisobutyronitrile for 12 hours under argon gave a 45% yield of 3-phenylcatechol. Catechol itself was obtained in a similar yield (ref.3). 

In the methylalizarin series a Diels-Alder adduct from naphtho-1,4-quinone and 

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