Catechol, also known as pyrocatechol or 1,2-dihydroxybenzene, is a toxic organic compound with the molecular formula C₆H₄(OH)₂. It is the ortho isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. 

Approximately 50% of the synthetic catechol is consumed in the production of pesticides, the remainder being used as a precursor to fine chemicals such as perfumes and pharmaceuticals. It is a common building block in organic synthesis.

Skin contact with catechol causes eczematous dermatitis in humans. In humans, absorption through the skin results in an illness resembling that induced by phenol, except convulsions are more pronounced. ... EPA has not classified catechol with respect to potential carcinogenicity.

PYROCATECHOL