Sulfamic acid

Sulfamic acid

Chembox new
Name = Sulfamic acid
ImageFile = Sulfamic.png ImageName = Sulfamic acid
IUPACName = Sulfamic acid
Section1 = Chembox Identifiers
CASNo = 5329-14-6

Section2 = Chembox Properties
Formula = H3NSO3
MolarMass = 97.10 g/mol
MeltingPt = 205 °C (401 °F)
BoilingPt = Decomposes
Density = 2.15 g/cm3
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 H3NSO3. This colorless, water-soluble compound finds many applications.

Sulfamic acid (H3NSO3) may be considered an intermediate compound between sulfuric acid (H2SO4), and sulfamide (H4N2SO2), effectively - though see below - replacing an -OH group with an -NH2 group at each step. This pattern can extend no further in either direction without breaking down the -SO2 group.

tructure and reactivity

First, it should be noticed that the compound is well described by the formula H3NSO3, not the tautomer H2NSO2(OH). The relevant bond distances are S=O, 1.44 and S-N 1.77 Å. The greater length of the S-N distance is consistent with a single bond. [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 37–45.] Furthermore, a neutron diffraction study located the hydrogen atoms, all three of which are 1.03 Å distant from nitrogen cite journal | author = R. L. Sass | year = 1960 | title = A neutron diffraction study on the crystal structure of sulfamic acid | journal = Acta Cryst. | volume = 13 | issue = 4 | month = April | pages = 320-324 | doi = 10.1107/S0365110X60000789 ] . The structures shown with this article are for the two main tautomers.

Sulfamic acid is a weak acid, "K"a = 1.01 x 10−1. 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 NH3 solution to give [HNSO3] 2−.:mathrm{(NH_2)HSO_3 + NaOH ightarrow NaNH_2SO_3 + H_2O}

Sulfamic acid melts at 205 °C before decomposing at higher temperatures to H2O, SO3, SO2, and N2.

Water solutions are unstable and slowly hydrolyze to ammonium bisulfate, but the crystalline solid is indefinitely stable under ordinary storage conditions.

With HNO2, sulfamic acid reacts to give N2, while with HNO3, it affords N2O.:mathrm{HNO_2 + (NH_2)HSO_3 ightarrow H_2SO_4 + N_2 + H_2O}:mathrm{HNO_3 + (NH_2)HSO_3 ightarrow H_2SO_4 + N_2O + H_2O}

The behavior of H3NSO3 resembles that of urea, (H2N)2CO, in some ways. Both feature amino groups linked to electron-withdrawing centers that can participate in delocalized bonding. Both liberate ammonia upon heating in water.


The most famous application of sulfamic acid is in the synthesis of compounds that taste sweet. Reaction with cyclohexylamine followed by addition of NaOH gives C6H11NHSO3Na, sodium cyclamate. Related compounds are also sweeteners, see acesulfame potassium.

Sulfamates (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 antibiotics, nucleoside/nucleotide human immunodeficiency virus (HIV) reverse transcriptase inhibitors, HIV protease inhibitors (PIs), anti-cancer drugs (steroid sulfatase and carbonic anhydrase inhibitors), anti-epileptic drugs, and weight loss drugs.

Sulfamic acid is used as an acidic cleaning agent, typically for metals and ceramics. It is a replacement for hydrochloric acid for the removal of rust. In households, it is often found as a descaling agent in detergents used for removal of limescale. From all acid, Sulfamic acid has the best water descaling property, thus also its application in cleaning dairy farm equipment and beer brewery. Although it is considered less corrosive than hydrochloric acid, in its application as acid cleaning, it is very common to find user adding corrosion inhibitor.

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
*Ingredient in Denture Tablets
*Coagulator for urea-formaldehyde resins
*Ingredient in fire extinguishing media. Sulfamic acid is the main raw material for Ammonium_sulfamate which is a widely used herbicide and fire retardant material for household product.
*Pulp and paper industry as a chloride stabilizer
*Synthesis of nitrous oxide by reaction with nitric acid


*MSDS []
*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

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Look at other dictionaries:

  • sulfamic acid — |səl|famik noun Etymology: International Scientific Vocabulary sulf + amide + ic 1. : a strong crystalline acid H2NSO3H made usually by reaction of sulfuric acid, sulfur trioxide, and urea and used chiefly as a weed killer, in cleaning metals,… …   Useful english dictionary

  • sulfamic acid — sulfamo rūgštis statusas T sritis chemija formulė H₂NSO₃H atitikmenys: angl. sulfamic acid rus. сульфаминовая кислота …   Chemijos terminų aiškinamasis žodynas

  • sulfamic acid — sul·fam·ic acid or chiefly Brit sul·pham·ic acid səl .fam ik n a strong crystalline acid H3NSO3 made usu. by reaction of sulfuric acid, sulfur trioxide, and urea …   Medical dictionary

  • sulfamic acid — noun the compound HNS(=O)OH and its N hydrocarbyl derivatives Syn: sulfamidic acid …   Wiktionary

  • sulfamic — adjective Of or pertaining to sulfamic acid or its derivatives …   Wiktionary

  • cyclohexylsulfamic acid — /suy kleuh hek seuhl sul fam ik, sik leuh /, Chem. See cyclamic acid. [CYCLO + HEXYL + sulfamic acid (appar. (chloro)sulf(onic) + AM(MONIA) + IC)] * * * …   Universalium

  • sulphamic acid — [sʌl famɪk] (US sulfamic acid) noun Chemistry a crystalline acid used in cleaning agents. Origin C19: from sulphur + amide + ic …   English new terms dictionary

  • sulphamic acid — /sʌlˌfæmɪk ˈæsəd/ (say sul.famik asuhd) noun a white crystalline solid, HSO3NH2, which gives weakly acid water solutions; used as a metal and ceramic cleaner and as a stabilising agent for chlorine and hypochlorite in swimming pools, etc. Also,… …   Australian-English dictionary

  • cyclohexylsulfamic acid — /suy kleuh hek seuhl sul fam ik, sik leuh /, Chem. See cyclamic acid. [CYCLO + HEXYL + sulfamic acid (appar. (chloro)sulf(onic) + AM(MONIA) + IC)] …   Useful english dictionary

  • sulfamidic acid — noun sulfamic acid …   Wiktionary

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