4-[(4-Methoxyphenyl)amino]phenol is a by-product intermediate during the synthesis of 4,4'-Iminodiphenol (I409010), which is derived from 4,4'-Dimethoxydiphenylamine (D461065), a diphenylamine derivative used as a chemical additive for cured rubber. 4,4'-Dimethoxydiphenylamine is highly toxic and may potentially induce chromosome abberation.