Hexa hydroxybenzene

Lithium aluminum hydride reduced p-benzoquinone to hydroquinone (yield 70%) [576] and anthraquinone to anthrahydroquinone in 95% yield [576]. Tin reduced p-benzoquinone to hydroquinone in 88% yield [174] Procedure 35, p. 214). Stannous chloride converted tetrahydroxy-p-benzoquinone to hexa-hydroxybenzene in 70-77% yield [929], and 1,4-naphthoquinone to 1,4-di-hydroxynaphthalene in 96% yield [180]. Other reagents suitable for reduction of quinones are titanium trichloride [930], chromous chloride [187], hydrogen sulfide [248], sulfur dioxide [250] and others. Yields are usually good to excellent. Some of the reagents reduce the quinones selectively in the presence of other reducible functions. Thus hydrogen sulfide converted 2,7-dinitro-phenanthrene quinone to 9,10-dihydroxy-2,7-dinitrophenanthrene in 90% yield [248]. 

Underpotentially deposited ad-atom layers of Pb, Tl, and Bi improve markedly the reversibility of the redox systems hydroquinone/p-benzoquinone [119, 120], pyrocatechol/o-benzoquinone [120], adrenaline/adrenalinequinone [121], hexa-hydroxybenzene/tetrahydroxy-1,4-benzoq-uinone [122], p-benzoquinone dioxime/ p-dinitrosobenzene [123], as well as the... 

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