Sulfamic acid 1945917 210591854 2008-05-06T16:02:28Z Chowbok 54304 clean up, Replaced: ages 37-45 → ages 37&ndash;45 (2) using [[Project:AutoWikiBrowser|AWB]] {{Chembox new | Name = Sulfamic acid | ImageFile = Sulfamic.png <!-- | ImageSize = 300px --> | ImageName = Sulfamic acid | IUPACName = Sulfamic acid | Section1 = {{Chembox Identifiers | CASNo = 5329-14-6 | SMILES = H<sub>2</sub>-N-SO<sub>3</sub>-H }} | Section2 = {{Chembox Properties | Formula = H<sub>3</sub>NSO<sub>3</sub> | MolarMass = 97.10 g/mol | MeltingPt = 205 °C (401 °F) | BoilingPt = Decomposes | Density = 2.15 g/cm<sup>3</sup> | pKa = 1.18 (1% solution @25 °C (77 °F) | Solvent = other solvents | SolubleOther = Soluble }} }} '''Sulfamic acid''', also known as '''amidosulfonic acid''', '''amidosulfuric acid''', '''aminosulfonic acid''', and '''sulfamidic acid''', is a molecular compound with the formula H<sub>3</sub>NSO<sub>3</sub>. This colorless, water-soluble compound finds many applications. Sulfamic acid (H<sub>3</sub>NSO<sub>3</sub>) may be considered an intermediate compound between [[sulfuric acid]] (H<sub>2</sub>SO<sub>4</sub>), and [[sulfamide]] (H<sub>4</sub>N<sub>2</sub>SO<sub>2</sub>), effectively - though see [[#Structure and reactivity|below]] - replacing an -OH group with an -NH<sub>2</sub> group at each step. This pattern can extend no further in either direction without breaking down the -SO<sub>2</sub> group. ==Structure and reactivity== First, it should be noticed that the compound is well described by the formula H<sub>3</sub>NSO<sub>3</sub>, not the [[tautomer]] H<sub>2</sub>NSO<sub>2</sub>(OH). The relevant bond distances are S=O, 1.44 and S-N 1.77 [[Ångström|Å]]. The greater length of the S-N distance is consistent with a single bond.<ref>J. W. Bats, P. Coppens, T. F. Koetzle "[http://dx.doi.org/10.1107/S0567740877002568 The Experimental Charge Density in Sulfur-Containing Molecules: A Study of the Deformation Electron Density in Sulfamic Acid at 78 K by X-ray and Neutron Diffraction]" ''Acta Crystallographica'' '''1977''', ''B33'', pages 37&ndash;45.</ref> Furthermore, a [[neutron diffraction]] study located the hydrogen atoms, all three of which are 1.03 [[Ångström|Å]] distant from nitrogen. The structures shown with this article are for the two main [[tautomer]]s. Sulfamic acid is a weak acid, K<sub>a</sub> = 1.01 x 10<sup>&minus;1</sup>. Because the solid is non-[[hygroscopic]], it is used as a standard in [[acidometry]] (quantitative assays of acid content). Double deprotonation can be effected in [[ammonia|NH<sub>3</sub>]] solution to give [HNSO<sub>3</sub>]<sup>2&minus;</sup>. :<math>\mathrm{(NH_2)HSO_3 + NaOH \rightarrow NaNH_2SO_3 + H_2O}</math> Sulfamic acid melts at 205 °C before decomposing at higher temperatures to H<sub>2</sub>O, SO<sub>3</sub>, SO<sub>2</sub>, and N<sub>2</sub>. With [[nitrous acid|HNO<sub>2</sub>]], sulfamic acid reacts to give [[nitrogen|N<sub>2</sub>]], while with [[nitric acid|HNO<sub>3</sub>]], it affords [[nitrous oxide|N<sub>2</sub>O]]. :<math>\mathrm{HNO_2 + (NH_2)HSO_3 \rightarrow H_2SO_4 + N_2 + H_2O}</math> :<math>\mathrm{HNO_3 + (NH_2)HSO_3 \rightarrow H_2SO_4 + N_2O + H_2O}</math> The behavior of H<sub>3</sub>NSO<sub>3</sub> resembles that of [[urea]], (H<sub>2</sub>N)<sub>2</sub>CO, in some ways. Both feature [[amino group]]s linked to electron-withdrawing centers that can participate in [[delocalized bond]]ing. Both liberate [[ammonia]] upon heating in water. ==Applications== The most famous application of sulfamic acid is in the synthesis of compounds that taste sweet. Reaction with [[cyclohexylamine]] followed by addition of [[sodium hydroxide|NaOH]] gives C<sub>6</sub>H<sub>11</sub>NHSO<sub>3</sub>Na, [[sodium cyclamate]]. Related compounds are also [[sweetener]]s, see [[acesulfame potassium]]. [[Sulfamate]]s (O-substituted-, N-substituted-, or di-/tri-substituted derivatives of sulfamic acid) have been used in the design of many types of therapeutic agents such as [[antibiotic]]s, nucleoside/nucleotide [[human immunodeficiency virus]] (HIV) [[reverse transcriptase inhibitor]]s, [[HIV protease inhibitor]]s (PIs), anti-cancer drugs ([[steroid sulfatase]] and [[carbonic anhydrase]] inhibitors), anti-[[epilepsy|epileptic]] drugs, and [[weight loss drug]]s. Sulfamic acid is used as an acidic [[cleaning]] agent, typically for [[metal]]s and [[ceramic]]s. It is a replacement for [[hydrochloric acid]] for the removal of [[rust]]. In households, it is often found as a [[descaling agent]] in [[detergent]]s used for removal of [[limescale]]. Sulfamic acid is used in the S.C. Johnson & Sons, Inc. "Scrubbing Bubbles Fizz-Its Toilet Tablets." *[[Catalyst]] for [[esterification]] process *[[Dye]] and [[pigment]] manufacturing *[[Herbicide]] *Ingredient in Denture Tablets *Coagulator for [[urea-formaldehyde resin]]s *Ingredient in [[fire retardant|fire extinguishing media]] *Pulp and paper industry as a chloride stabilizer *Synthesis of [[nitrous oxide]] by reaction with nitric acid ==References== {{Citationstyle|date=September 2007}} {{reflist}} *J. W. Bats, P. Coppens, T. F. Koetzle "The Experimental Charge Density in Sulfur-Containing Molecules: A Study of the Deformation Electron Density in Sulfamic Acid at 78 K by X-ray and Neutron Diffraction" Acta Crystallographica (1977). B33, pages 37&ndash;45. *[[MSDS]] http://www.osha.gov [http://www.osha.gov/dts/chemicalsampling/data/CH_268428.html] *Sulfamates and their therapeutic potential. Med Res Rev. 2005 Mar;25(2):186-228. Review. *R. J. Cremlyn “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). ISBN 0-471-95512-4 * {{Greenwood&Earnshaw}} ==External links== {{commonscat|Sulfamic acid}} [[Category:Sulfur compounds]] [[Category:Acids]] [[Category:Household chemicals]] [[Category:Cleaning product components]] [[de:Amidosulfonsäure]] [[it:Acido ammidosolfonico]] [[ja:スルファミン酸]] [[tr:Sulfamik asit]] [[zh:氨基磺酸]]