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. ==Synthesis== Sulfanilic acid can be produced by sulfonation of aniline: ==Applications== As the compound read... Found on http://en.wikipedia.org/wiki/Sulfanilic_acid