Synthesis chemical lab is one of the leading whole sale and retail trader in coimbatore , we are the leading supplier of chemicals, speciality chemicals , and lab and commercial grade. Naphthol benzein is a dye belonging to the Benzein family insoluble in water and soluble in alcohol. α-Naphthol benzein is primarily used as an indicator for pH range 8.2-10.0 (mostly in acid-base titrations), causing a color change for the neutral solutions turning alkaline. Naphthol is made of two aromatic compounds. It has 10 carbon atoms, 8 hydrogen atoms, and one oxygen atom. The carbon and hydrogen atoms in naphthol form its two benzene rings. A hydroxyl functional group (OH) is attached to one of the benzene rings and is made of one oxygen atom and one hydrogen atom. Synthesis chemical lab.