The compound is well described by the molecular formula H3NSO3 rather than the tautomer H2NSO2(OH). The phase key distance of S=O is 1.44 A, and the key distance of S-N is 1.77 A. The larger length of s-n is consistent with a single bond. In addition, neutron diffraction studies located hydrogen atoms, all three of which were 1.03 angstroms away from nitrogen. In solid state, sulfamic acid molecules are well described as amphoteric ions.

hydrolysis

Crystalline solids are infinitely stable under ordinary storage conditions, but an aqueous solution of sulfamic acid hydrolyzes slowly to ammonium bisulfate according to the following reaction:

H3NSO3 + H2O → [NH4]+[HSO4]−

It behaves like urea (H2N)2CO. Both have an amino group attached to an electron-sucking center that can participate in delocalized bonding. Both release ammonia when heated in water, urea releases carbon dioxide, and sulfamic acid releases sulfuric acid.

Acid-base reaction

Sulfamic acid is a moderately strong acid with Ka = 0.101 (pKa = 0.995). Because solids do not absorb moisture, they are used as a standard for acidity determination (quantitative determination of acid content).

H3NSO3 + NaOH → NaH2NSO3 + H2O

In ammonia solution, double deprotonation can be carried out to obtain anion HNSO2−

3.

H3NSO3 + 2 NH3 → HNSO2−3 + 2 NH+4

Reacts with nitric acid and nitrous acid

Sulfamic acid reacts with nitrite to form nitrogen:

HNO2 + H3NSO3 → H2SO4 + N2 + H2O

When reacted with nitric acid, it produces nitrous oxide:

HNO3 + H3NSO3 → H2SO4 + N2O + H2O

It reacts with hypochlorite

The reaction of excess hypochlorite ions with sulfamate or sulfamate reversibly yields n-chloraminosulfonate and N, n-dichloraminosulfonate ions.

HClO + H2NSO3H → ClNHSO3H + H2O

HClO + ClNHSO3H, Cl2NSO3H + H2O

Sulfamic acid is therefore used as a hypochlorite scaver in the oxidation of aldehydes with chlorite (e.g. Pinnick oxidation).

Reaction with alcohol

When heated, sulfamic acid reacts with alcohols to form corresponding organic sulfates. It is more expensive than other reagents, such as chlorosulfonic acid or fuming sulfuric acid, but is also significantly milder and does not sulfonate aromatic rings. The product is produced in the form of its ammonium salt. This reaction can be catalyzed by the presence of urea. Sulfamic acid will not react with ethanol at temperatures below 100°C in the absence of any catalyst.

ROH + H2NSO3H → ROS(O)2O- + NH+4

An example of this reaction is the production of 2-ethylhexyl sulfate by combining sulfamic acid with 2-ethylhexanol, a wetting agent used in cotton mercerization.