1-Nitroso-2-naphthol

1-Nitroso-2-naphthol is an organic compound with the formula C10H6(NO)OH. It is one of several possible nitrosonaphthols, and the most studied for applications as an indicator and a dye.

Synthesis and reactions
1-Nitroso-2-naphthol can be prepared by treatment of 2-naphthol with nitrous acid:
 * C10H7OH + HNO2  ->  C10H6(NO)OH  +  H2O

Its conjugate base forms deeply colored complexes with iron(II) and cobalt(II), complexes [M(C10H6(NO)O)3]2-. The deep colors of these complexes results from the delocalized bonding within each five-membered chelate ring. These species can be classified as nitroso complexes.