1-Naphthylamine-4,6,8-trisulfonic acid

Chemical Properties

1-Aminonaphthalene-4,6,8-trisulfonic acid [17894-99-4]. (8-aminonaphthalene1,3,5-trisulfonic acid), B acid, C10H9NO9S3, Mr 383.36, is reduced with zinc and alkali to 1- aminonaphthalene-4,6-disulfonic acid. Heating with aqueous sulfuric acid causes desulfonation to form 1-aminonaphthalene-6,8-disulfonic acid. Sulfonation (25 % oleum, 90℃) gives the sultam of 1-aminonaphthalene-2,4,6,8-tetrasulfonic acid.

Uses

Alkali fusion of B acid yields K acid. A special outlet for purified B acid is in the synthesis of the drug suramin sodium (Bayer 205) . 1-Aminonaphthalene-4,6,8-trisulfonic acid is acylated with 2-nitrotoluyl chloride, and this product is reduced and acylated with mnitrobenzoyl chloride. This intermediate is reduced and finally phosgenated to give suramin sodium, which has been used to treat trypanosomiasis and onchocerciasis.

Production Methods

Naphthalene is sulfonated under conditions that maximize formation of the 1,3,5-trisulfonic acid, followed by nitration with H2SO4– HNO3 in situ at 35℃. After quenching, neutralization with calcium carbonate, and reduction of the nitro-derivative with iron under acid conditions, the byproduct 1- aminonaphthalene-3,6,8-trisulfonic acid (18 % yield) is selectively precipitated by acidification. The desired isomer is then precipitated by further acidification and salting of the filtrates, and finally purified by reprecipitation. Overall yield is 25 – 30 %.