General Description
White powder with faint purple tinge. Grayish-white flat crystals. Becomes anhydrous at around 212°F. Low toxicity (used medicinally).
Reactivity Profile
4-AMINOBENZENE SULFONIC ACID(121-57-3) is an amino acid. Reacts weakly with both acids and bases.
Air & Water Reactions
Insoluble in water.
Fire Hazard
Flash point data for this chemical are not available, however 4-AMINOBENZENE SULFONIC ACID is probably combustible.
Description
Sulfanilic acid (4-amino benzene sulfonic 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.
Chemical Properties
greyish-white crystals or powder
Uses
A toxic metabolite of Tartrazine (T007700). Used as Ehrlich’s reagent, for detecting of nitrites. Antibacterial.
Application
As the compound readily form diazo compounds, it is used to make dyes and sulpha drugs . This property is also used for the quantitative analysis of nitrate and nitrite ions by diazonium coupling reaction with N-(1-Naphthyl) ethylene diamine , resulting in an azo dye, and the concentration of nitrate or nitrite ions were deduced from the color intensity of the resulting red solution by colorimetry.
It is also used as a standard in combustion analysis.
Definition
ChEBI: An aminobenzenesulfonic acid that is aniline sulfonated at the para-position.
Synthesis
Sulfanilic acid can be produced by sulfonation of aniline.
Purification Methods
Crystallise the acid (as dihydrate) from boiling water. Dry it at 105o for 2-3hours, then over 90% H2SO4 in a vacuum desiccator. The S-benzylisothiuronium salt has m 187o (from aqueous EtOH). [Beilstein 14 IV 2655.]
