Orcin

Orcin, or ORCINAL, $C\_6H\_3(CH\_3)(OH)\_2$. This substance is found in the free state in the lichens from which Archil and Litmus (q.v.) are prepared. It is formed when the acids which occur in these plants are boiled with baryta water or submitted to dry distillation. It is also prepared artificially from the nitro-derivatives of the hydrocarbon toluene. As shown by the formula, orcin is a di-acid phenol, and appears in large colourless crystals which turn a reddish-brown colour when exposed to the air. By the action of ammonia and the oxygen of the air it is converted into orein, $C\_7H\_7NO\_3$, which is the colouring matter of archil.