Sulfamic acid
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| Names | |||
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IUPAC name
Sulfamic acid
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| Identifiers | |||
5329-14-6 
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| 3D model (Jmol) | Interactive image | ||
| ChEBI |
CHEBI:9330
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| ChEMBL |
ChEMBL68253
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| ChemSpider |
5767
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| ECHA InfoCard | 100.023.835 | ||
| EC Number | 226-218-8 | ||
| PubChem | 5987 | ||
| RTECS number | WO5950000 | ||
| UN number | 2967 | ||
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| Properties | |||
| H3NSO3 | |||
| Molar mass | 97.10 g/mol | ||
| Appearance | white crystals | ||
| Density | 2.15 g/cm3 | ||
| Melting point | 205 °C (401 °F; 478 K) decomposes | ||
| Moderate, with slow hydrolysis | |||
| Solubility | Moderately soluble in DMF, Slightly soluble in MeOH, Insoluble in hydrocarbons | ||
| Acidity (pKa) | 1.0 | ||
| Hazards | |||
| Safety data sheet | ICSC 0328 | ||
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EU classification (DSD)
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Irritant (Xi) | ||
| R-phrases | R36/38 R52/53 | ||
| S-phrases | (S2) S26 S28 S61 | ||
| Related compounds | |||
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Other cations
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Ammonium sulfamate | ||
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |||
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 melts at 205 °C before decomposing at higher temperatures to H2O, SO3, SO2, and N2.
Sulfamic acid (H3NSO3) may be considered an intermediate compound between sulfuric acid (H2SO4), and sulfamide (H4N2SO2), effectively 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. Sulfamates are derivatives of sulfamic acid.
Sulfamic acid is produced industrially by treating urea with a mixture of sulfur trioxide and sulfuric acid (or oleum). The conversion is conducted in two stages:
In this way, approximately 96,000 tons were produced in 1995.
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. Furthermore, a neutron diffraction study located the hydrogen atoms, all three of which are 1.03 Å distant from nitrogen. In the solid state, the molecule of sulfamic acid is well described by a zwitterionic form :
Water solutions are unstable and slowly hydrolyze to ammonium bisulfate, but the crystalline solid is indefinitely stable under ordinary storage conditions. Its behavior resembles that of urea, (H2N)2CO. Both feature amino groups linked to electron-withdrawing centers that can participate in delocalized bonding. Both liberate ammonia upon heating in water.
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