O-Anisidine
"o"-Anisidine (2-anisidine) is an organic compound with the formula CHOCHNH. A colorless liquid, commercial samples can appear yellow owing to air oxidation. It is one of three isomers of the methoxy-containing aniline derivative. Production and use. It is prepared via methanolysis of 2-chloronitrobenzene: The resulting "o"-nitroanisole is reduced to "o"-anisidine. "o"-Anisidine is used in the manufacture of dyes. It is nitrated to give 4-nitroanisidine. It is also a precursor to "o"-dianisidine. One special use is as a heartwood indicator. An acid solution of "o"-anisidine is diazotized by adding a sodium nitrite solution. This mixture  is applied to the wood and by reaction with polyphenols in the heartwood a reddish brown azo dye is formed. Safety and environmental aspects. "o"-Anisidine is a dangerous pollutant from the production of dyes. It is listed as RCRA hazardous waste, with the code K181. The International Agency for Research on Cancer (IARC) has classified "o"-anisidine as a Group 2B, possible human carcinogen.