SULFAMIC ACID AND SULFAMATES

Sulfamic acid [5329-14-6] (amidosulfuric acid), HSO2NH2, molecular weight 97.09, is a monobasic, inorganic, dry acid and the monoamide of sulfuric acid. Sulfamic acid is produced and sold in the form of water-soluble crystals. This acid was known and prepared in laboratories for nearly a hundred years before it became a commercially available product. The first preparation of this acid occurred around 1836 (1). Later work resulted in identification and preparation of sulfamic acid in its pure form (2). In 1936, a practical process which became the basis for commercial preparation was developed (3,4). This process, involving the reaction of urea with sulfur trioxide and sulfuric acid, continues to be the main method for production of sulfamic acid. 

Sulfamic acid has a unique combination of properties that makes it particularly well suited for scale removal and chemical cleaning operations, the main commercial appHcations. Sulfamic acid is also used in sulfation reactions, pH adjustment, preparation of synthetic sweeteners (qv), and a variety of chemical processing appHcations. Salts of sulfamic acid are used in electroplating (qv) and electroforrning operations as well as for manufacturing flame retardants (qv) and weed and hnish killers (see Herbicides). 

Physical, Sulfamic acid is a diy acid having oithorhombic crystals. The pure crystals ate nonvolatile, nonhygroscopic, colodess, and ododess. The acid is highly stable up to its melting point and may be kept for years without change in properties. Selected physical properties of sulfamic acid are hsted in Table 1. Other properties are available in the hterature (5—8). 

Chemical Properties. Selected chemical properties of sulfamic acid are Hsted in Table 2 other properties are Hsted in Reference 9. 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

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