Pyrocatechol(redirected from O-benzenediol)
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(o-dihydroxybenzene), a dihydric phenol; a colorless crystalline solid with a phenol odor. Melting point, 104°C; boiling point, 246°C. Darkens rapidly upon exposure to air; soluble in water, alcohol, and ether.
Pyrocatechol fuses with phthalic anhydride to yield the dyes alizarin and hystazarin. It is alkylated by isobutylene to tert-butylpyrocatechol, an effective inhibitor of free radical processes. Pyrocatechol is used as a photographic developer.
Pyrocatechol is found in the molecules of many native aromatic compounds (for example, tannins), from which it was first obtained by dry distillation. It is a source material in the preparation of adrenalin; the monomethyl ether of pyrocatechol is called guaiacol. Pyrocatechol is commercially prepared by alkaline fusion of o-chlorophenol or o-phenolsulfonic acid.