There are two versions of Naphthol available. There’s both 1-Naphthol and 2-Naphthol that are used commercially. Both types of Naphthol are soluble in chloroform, ethers, and simple alcohols. Also, both 1-Naphthol and 2-Naphthol are also used in humans and livestock as a biomarker to see if the subject has been exposed to polycyclic aromatic hydrocarbons. 1-Naphthol is a white solid that’s fluorescent. 1-Naphthol is different from 2-Naphthol as it’s hydroxyl group is in a different location on the naphthalene ring. 1-Naphthol is used as a precursor for some insecticides, pharmaceuticals, azo dyes, and can be used for testing, such as Molisch’s test, rapid furfural test, Voges-Proskauer test, or Sakaguchi test. 2-Naphthol is a colorless or sometimes yellow crystalline solid that’s fluorescent. 2-Naphthol is used for creating dyes. It makes Sudan dyes, one through four. It’s also the precursor to BINOL that is also used for creating dyes and organic synthesis.