Sulfanilic acid (4-aminobenzenesulfonic acid ) is an off-white crystalline solid which finds application in quantitative analysis of nitrate and nitrite ions. The solid acid exists as a zwitterion, and has an unusually high melting point. Sulfanilic acid has four primary end uses. It is used as an intermediate in the production of yellow food dye, specific pharmaceutical applications, optical brighteners for white paper and as a concrete additive. The sulfanilic acid intermediate can be purchased in four different grades – technical grade, pure grade, sodium sulfanilate solution and sodium sulfanilate dry powder.
PHYSICAL DESCRIPTION: White powder with faint purple tinge. Grayish-white flat crystals. Becomes anhydrous at around 212°F. Low toxicity (used medicinally).
- Molar mass
- 173.19 g/mol
- CAS Number
- 1.4862 g/cm3 at 20°C (68°F)
- 99% (ACS Reagent)
- Initial boiling point and boiling range
- ca.300°C (572°F) – OECD Test Guideline 103 – Decomposes below the boiling point.
- Water solubility
- 12.51 g/l at 20°C (68°F) – OECD Test Guideline 105 – soluble
- Melting point/freezing point
- >300°C (>572°F) – lit.
- Partition coefficient: n-octanol/wate
- log Pow: – 2.297 at 25°C (77°F)
- Auto-ignition temperature
- 331°C (628°F)
- Decomposition temperature
- ca.300°C (572°F)