Hydroxylammonium sulfate

Names
Other names Hydroxylamine sulfate
Identifiers
CAS Number	10039-54-0 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3183215
ChemSpider	23229 Y
ECHA InfoCard	100.030.095
EC Number	233-118-8
PubChem CID	24846
RTECS number	NC5425000
UNII	49KP498D4O Y
UN number	2865
CompTox Dashboard (EPA)	DTXSID2025424
InChI InChI=1S/2H4NO.H2O4S/c2*1-2;1-5(2,3)4/h2*2H,1H3;(H2,1,2,3,4)/q2*+1;/p-2 Y Key: VGYYSIDKAKXZEE-UHFFFAOYSA-L Y InChI=1/2H4NO.H2O4S/c2*1-2;1-5(2,3)4/h2*2H,1H3;(H2,1,2,3,4)/q2*+1;/p-2 Key: VGYYSIDKAKXZEE-NUQVWONBAN
SMILES [O-]S([O-])(=O)=O.O[NH3+].O[NH3+]
Properties
Chemical formula	H8N2O6S
Molar mass	164.14 g/mol
Appearance	white crystalline to fine product, slightly hygroscopic
Density	1.88 g/cm3
Melting point	120 °C (248 °F; 393 K) decomposes
Solubility in water	58.7 g/100 ml (20 °C)
Structure[1]
Crystal structure	Monoclinic
Space group	P21/c
Lattice constant	a = 7.932±0.002 Å, b = 7.321±0.002 Å, c = 10.403±0.003 Å α = 90°, β = 106.93±0.03°, γ = 90°
Formula units (Z)	4
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H290, H302, H312, H315, H317, H319, H351, H373, H400, H412
Precautionary statements	P201, P202, P234, P260, P261, P264, P270, P272, P273, P280, P281, P301+P312, P302+P352, P305+P351+P338, P308+P313, P312, P314, P321, P322, P330, P332+P313, P333+P313, P337+P313, P362, P363, P390, P391, P404, P405, P501
NFPA 704 (fire diamond)	3 1 2
Safety data sheet (SDS)	External MSDS
Related compounds
Other anions	Hydroxylammonium nitrate Hydroxylammonium chloride
Other cations	Ammonium sulfate Hydrazinium sulfate
Related compounds	Hydroxylamine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Hydroxylammonium sulfate [NH₃OH]₂SO₄, is the sulfuric acid salt of hydroxylamine. It is primarily used as an easily handled form of hydroxylamine, which is explosive when pure.

Synthesis

Hydroxylammonium sulfate is prepared industrially via the Raschig hydroxylamine process, which involves the reduction of nitrite with bisulfite. This initially gives hydroxylamine disulfonate, which is hydrolysed to hydroxylammonium sulfate:^[2] It can also be obtained by the acid-base reaction of hydroxylamine with sulfuric acid:

2NH₂OH(aq) + H₂SO₄(aq) → (NH₃OH)₂SO₄(aq)

Applications

Hydroxylammonium sulfate is used in organic synthesis to convert aldehydes and ketones to oximes, carboxylic acids and their derivatives (e.g. esters) to hydroxamic acids, isocyanates to N-hydroxyureas and nitriles to amidoximes. Hydroxylammonium sulfate is also used to generate hydroxylamine-O-sulfonic acid from oleum or chlorosulfuric acid.

Hydroxylammonium sulfate is used in the production of anti-skinning agents, pharmaceuticals, rubber, textiles, plastics and detergents. It is a radical scavenger that terminates radical polymerization reactions and serves as an antioxidant in natural rubber. (NH₃OH)₂SO₄ is a starting material for some insecticides, herbicides and growth regulators. It is used in photography as a stabiliser for colour developers and as an additive in photographic emulsions in colour film.

Decomposition

At 120 °C, hydroxylammonium sulfate begins to decompose to sulfur trioxide, nitrous oxide, water, and ammonia^{[dubious – discuss]}:

2(NH₃OH)₂SO₄ → 2SO₃ + N₂O + 2NH₃ + 5H₂O

The reaction is exothermic above 138 °C, and is most exothermic at 177 °C.^[3] Metals (especially copper, its alloys and its salts) catalyse the decomposition of hydroxylammonium sulfate. The instability of this compound is mainly due to the hydroxylammonium ion's weak nitrogen to oxygen single bond.