Intermediate

H Acid
CAS: 90-20-0
Content: 80% (MW:319); 85% (MW:341)
Packing: 25kg per bag

H acid, chemically known as 1-amino-8-naphthol-3,6-disulfonic acid (CAS No. 90-20-0, molecular formula C10H9NO7S2, molecular weight 319.30), is typically available as a white to gray or yellow crystalline powder or paste. It has a density of approximately 1.9 g/cm³, a melting point above 300°C, and is slightly soluble in water, ethanol, and ether but soluble in alkaline solutions. When exposed to ferric chloride solution, it turns reddish-brown. H acid serves as a crucial intermediate in the production of azo dyes, used to manufacture various dyes such as Acid Black 10B, Reactive Brilliant Red K-2BP, Direct Blue, and Direct Fast Blue. Its upstream raw materials include amino T acid and others. The primary preparation method involves high-temperature and high-pressure reactions of an isomeric mixture containing over 65% by weight of 1-naphthol-3,6,8-trisulfonic acid with alkali metal hydroxides, followed by acidification with waste sulfuric acid to separate monovalent alkali metal salts [1]. A newer production process includes alkaline fusion in an ammonia atmosphere, which suppresses side reactions and increases H acid yield to 85%.