Description
Amidosulfonic acid, also known as amidosulfuric acid or sulfamic acid (H2NSO3H) is an organic chemical compound containing the amino group (-NH2) and the sulfonic group (-SO3H). It is a colorless crystalline substance that is primarily used as a component of cleaning agents, e.g. in detergents, disinfectants, and also as an acidifying agent in the food and pharmaceutical industries. Sulfamic acid has hygroscopic properties, which means that it easily attracts and binds water molecules from the environment. In addition, it undergoes ionic dissociation in water. It is a medium-strength acid with moderate toxicity, it should be used and stored carefully. According to ADR regulations, amidosulfonic acid is classified as a dangerous substance, UN number 2967.
Amidosulfonic acid is typically obtained by dissolving urea [CO(NH2)2] in oleum (SO3 solution in anhydrous sulfuric acid). Alternatively, a two-step reaction using sulfur dioxide (SO₃) and ammonia (NH₃) is used. The reaction product of these compounds is ammonium amidosulfate (NH₄HSO₃), which is then heated to release ammonia (NH₃) and form amidosulfonic acid. In addition, amidosulfonic acid can be obtained by reacting ammonium chloride (NH₄Cl) with chlorine sulfate (SO₂Cl₂). The production process should take place in a controlled environment to avoid excessive emissions of SO₃ and NH₃, both of which are toxic.
Amidosulfonic acid reacts with bases to form salts, called amidosulfates. In addition, in the presence of a catalyst (e.g. sulfuric acid), amidosulfonic acid reacts with alcohols through the esterification reaction. In this reaction, sulfonic esters are formed. Amidosulfonic acid also reacts with active metals (e.g. magnesium or zinc), forming salts and releasing hydrogen. Amidosulfonic acid is both an oxidizing and reducing agent. As a result of reduction, it produces ammonia, which can be transformed into sulfuric acid (VI) in the face of strong oxidation. In addition, it reacts with halogens: in an acidic environment amidosulfonic acid acts as a reducing agent, reacting with chlorine or bromine and transforming the halogens into hydrohalic acids. Sulfamic acid can also react with hydrogen peroxide (H₂O₂) to form persulfates. Sulfamic acid reactions are useful in chemical analysis: titration (standard acid in the titration of alkaline solutions) and as a chlorine stabilizer (binds excess chlorine, making it useful in water analysis).
