8921. Sulfamic Acid

Nomenclature

CAS number: 5329-14-6
Amidosulfonic acid.
H3NO3S; mol wt 97.09.
H 3.11%, N 14.43%, O 49.44%, S 33.03%.

Description and references

Obtained from chlorosulfonic acid and ammonia, or by heating urea with H2SO4. Purification: Sisler et al., Inorg. Synth. 2, 178 (1946). Toxicity data: Ambrose, J. Ind. Hyg. Toxicol. 25, 26 (1943). Reviews: Audrieth et al., Chem. Rev. 26, 49 (1940); Burton, Nickless, “Amido- and Imido-Sulfonic Acids” in Inorganic Sulphur Chemistry, G. Nickless, Ed. (Elsevier, New York, 1968) pp 607-627, 661-667; E. B. Bell in Kirk-Othmer Encyclopedia of Chemical Technology vol. 21 (Wiley-Interscience, New York, 3rd ed., 1983) pp 949-960. Brief review of synthetic applications: B. Wang, Synlett 2005, 1342-1343.

Chemical structure

Properties

Orthorhombic crystals. d 2.15. mp ≈205° (dec). Corrosive. Stable when dry but in soln slowly hydrolyzes forming ammonium bisulfate. Sol in 6.5 parts water at 0°, in about 2 parts water at 80°. Sulfuric acid decreases soly in water. Sparingly sol in alcohol, methanol; slightly sol in acetone. Insol in ether. Freely sol in nitrogenous bases, e.g., liquid ammonia, also in nitrogen contg organic solvents, e.g., pyridine, formamide, dimethylformamide. Immiscible with toluene, THF. A strong acid; pH of a 1% soln at 25° 1.18. Can be titrated with bases by means of indicators showing color change between pH 4.5 to 9. MLD orally in rats: 1.6 g/kg (Ambrose).

Caution

Moderately irritating to skin, mucous membranes.

Use

As standard in alkalimetry and acidimetry; in acid cleaning; in nitrite removal; in chlorine stabilization for use in swimming pools, cooling towers, paper mills. Solid-acid catalyst in organic synthesis. The acid or its ammonium salt has been recommended for flameproofing fabrics and wood. Metal salts are used in electroplating. Ammonium sulfamate, q.v., is also widely used as a weed killer.