Hydroquinone 1,4-Benzenediol

The close electrochemical relationship of the simple quinones, (2) and (3), with hydroquinone (1,4-benzenediol) (4) and catechol (1,2-benzenediol) (5), respectively, has proven useful in ways extending beyond their offering an attractive synthetic route. Photographic developers and dye syntheses often involve (4) or its derivatives (10). Biochemists have found much interest in the interaction of mercaptans and amino acids with various compounds related to (3). The reversible redox couple formed in many such examples and the frequendy observed quinonoid chemistry make it difficult to avoid a discussion of the aromatic reduction products of quinones (see Hydroquinone, resorcinol, and catechol). 

Pure (A)-1 -chloropropene was obtained by careful distillation of a mixture of (E)- and ( )-l -chloropropene (available from Columbia Organic Chemicals Company Inc.) using a Nester-Faust Teflon annular spinning band column [(Z)-l-chloropropene has b.p. 33° (A)-l-chloropropene has b.p. 37°]. Small quantities of powdered sodium bicarbonate and hydroquinone (1,4-benzenediol) placed in the distillation flask inhibit acid-catalyzed isomerization and polymerization. Gas chromatographic analysis of the material used in these experiments on a 4-m., 15% l,2,3-tris(2-cyanoethoxy)propane (TCEP) on Chromosorb P column, operated at room temperature, typically indicated that it had isomeric purity >99.9%. (A)- 1-Chloropropene is stable for several months at room temperature, but it should be stored in a cool place. 

Oxidation of hydroquinone (1,4-benzenediol) produces a compound known as /)-benzoquinone. The oxidation can be brought about by mild oxidizing agents, and, overall, the oxidation amounts to the removal of a pair of electrons (2 e") and two protons from hydroquinone. (Another way of visualizing the oxidation is as the loss of a hydrogen molecule, H H, making it a dehydrogenation.)... 

Homoveratrole. 3,4-Dimelhoxytoluene, 830 Hydroquinone. 1,4-Benzenediol, 716-717 Hydroquinone diacetate. 1,4-Benzenediol diacetate, 716, 801 Hydroquinone monomethylether. 4-Methoxyphenol, 1008 Hydroquinone dimethylether. 1,4-Dimethoxybenzene, 111, 1119... 

Homoveratroyl chloride. 3,4-Dimethoxyphenylacetyl chloride, 1482, 1518, 1703 Hydroquinone. 1,4-Benzenediol, 1260, 1409... 

---