Hydroxylammonium sulfate

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.

Hydroxylammonium sulfate
Names
Other names
Hydroxylamine sulfate
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.030.095
EC Number
  • 233-118-8
RTECS number
  • NC5425000
UNII
UN number 2865
  • InChI=1S/2H4NO.H2O4S/c2*1-2;1-5(2,3)4/h2*2H,1H3;(H2,1,2,3,4)/q2*+1;/p-2 checkY
    Key: VGYYSIDKAKXZEE-UHFFFAOYSA-L checkY
  • 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
  • [O-]S([O-])(=O)=O.O[NH3+].O[NH3+]
Properties
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
58.7 g/100 ml (20 °C)
Hazards
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
Warning
H290, H302, H312, H315, H317, H319, H351, H373, H400, H412
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)
NFPA 704 four-colored 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).
checkY verify (what is checkY☒N ?)
Infobox references

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:[1] It can also be obtained by the acid-base reaction of hydroxylamine with sulfuric acid:

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

Applications
Main article: Hydroxylamine § Reactions

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:

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

The reaction is exothermic above 138 °C, and is most exothermic at 177 °C.[2] 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.

References
  1. Oblath, S. B.; Markowitz, S. S.; Novakov, T.; Chang, S. G. (December 1982). "Kinetics of the initial reaction of nitrite ion in bisulfite solutions" (PDF). The Journal of Physical Chemistry. 86 (25): 4853–4857. doi:10.1021/j100222a005.
  2. BASF hydroxylammonium sulfate product page
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