Naphthol yellow S is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon- hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

that is a

dye A dye is a colored substance that chemically bonds to the substrate to which it is being applied. This distinguishes dyes from pigments which do not chemically bind to the material they color. Dye is generally applied in an aqueous solution and ...

. It is a derivative of

1-naphthol 1-Naphthol, or α-naphthol, is a fluorescent organic compound with the formula . It is a white solid. It is an isomer of 2-naphthol differing by the location of the hydroxyl group on the naphthalene ring. The naphthols are naphthalene homologues ...

. At one time it was a popular food colorant but it was delisted in 1959 in the U.S.

References

Acid dyes Naphthalenesulfonates Nitronaphthalenes Organic sodium salts {{Organic-compound-stub