Sodium naphthionate
Sodium naphthionate, chemically sodium 4-amino-1-naphthalenesulfonate (CAS 130-13-2), is a crystalline aromatic amine salt manufactured industrially by sulfonating naphthalene and then introducing the amino function. It appears as a pale grey to light pink crystalline powder, typically with an assay of 95 percent or higher based on nitrogen, and dissolves readily in water while remaining only slightly soluble in organic solvents. The solid is stable under ordinary storage but should be protected from light and strong oxidisers to prevent discolouration and oxidative degradation. As a bifunctional molecule carrying both a primary aromatic amine and a sodium sulfonate group it is a classical diazo and coupling component: the sulfonate guarantees high aqueous solubility, while the free amino group can be diazotised, acylated or condensed, giving chemists a convenient handle for building larger conjugated aromatic systems.
1. Dyestuff manufacture: the dominant commercial use is as a diazo component and coupling intermediate in the production of azo, direct, acid and reactive dyes, especially naphthol-based colourants for textiles, paper, leather and printing inks, where it contributes brilliant shade and good fastness.
2. Analytical reagent: known historically as Riegler’s reagent, its diazotised form is used for the qualitative and quantitative detection of nitrous acid, nitrite and iodine, and it serves as a reducing agent and colorimetric reagent in titrimetric, photometric and kinetic analytical methods.
3. Pharmaceutical and medicinal application: it has been employed as an antidote in nitrite and iodine poisoning and has been studied for antiseptic, anti-inflammatory and metal corrosion-inhibiting activity in surface-treatment formulations and coatings.
4. Other industrial and laboratory uses: an intermediate for sulfonated agrochemicals, photographic chemicals and optical brighteners, and a reagent for diazotisation and coupling studies. Store sealed, dry and away from oxidising agents and direct sunlight; avoid dust generation during weighing and observe standard industrial hygiene.
Product Name: Sodium naphthionate
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