What is "pyrocatechol"

catechol \cat"e*chol\ (k[a^]t"[e^]*k[add]l`), n. [.] any of a group of chemicals having a benzene ring substituted with two hydroxyl groups in ortho position, especially ortho-dihydroxybenzene itself ( C6H6O2), also called pyrocatechol, used in photography and as a reagent.

n. (context organic compound English) A dihydric phenol, benzene-1,2-diol, present in some tars.