Nitrosylsulfuric acid

Nitrosylsulfuric acid

Names
IUPAC name Nitrosylsulfuric acid
Other names nitrosonium bisulfate, chamber crystals
Identifiers
CAS Number	7782-78-7
ChemSpider	74147
Jmol interactive 3D	Image
PubChem	82157
InChI InChI=1S/HNO5S/c2-1-6-7(3,4)5/h(H,3,4,5) Key: VQTGUFBGYOIUFS-UHFFFAOYSA-N InChI=1/HNO5S/c2-1-6-7(3,4)5/h(H,3,4,5) Key: VQTGUFBGYOIUFS-UHFFFAOYAM
SMILES O=NOS(=O)(=O)O
Properties
Chemical formula	HNO5S
Molar mass	127.08 g/mol
Appearance	pale yellow crystals
Density	1.612 g/mL in 40% sulfuric acid soln
Melting point	73.5 °C (164.3 °F; 346.6 K)
Boiling point	decomposes
Solubility in water	decomposes
Solubility	soluble in H2SO4
Hazards
Main hazards	oxidizer
Related compounds
Other anions	NOCl
Other cations	NaHSO4
Related compounds	NOBF4
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
verify (what is  ?)
Infobox references

Nitrosylsulfuric acid is the chemical compound with the formula NOHSO₄. It is a colourless solid that is used industrially in the production of caprolactam,^[1] and was formerly part of the lead chamber process for producing sulfuric acid.

Synthesis and reactions

A typical procedure entails dissolving sodium nitrite in concentrated sulfuric acid in an ice bath:^[2][3]

HNO₂ + H₂SO₄ → NOHSO₄ +H₂O

The molecule can also be viewed as the mixed inorganic anhydride of sulfuric acid and nitrous acid. Alternatively, it can be prepared by the reaction of nitric acid and sulfur dioxide.^[4]

NOHSO₄ is useful in organic chemistry to prepare diazonium salts from amines. Related NO-delivery reagents include nitrosonium tetrafluoroborate ([NO]BF₄) and nitrosyl chloride.

References

1. Ritz, J.; Fuchs, H.; Kieczka, H.; Moran, W. C. (2002). "Caprolactam". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a05_031.
2. Hodgson, H. H.; Mahadevan, A. P.; Ward, E. R. (1955). "1,4-Dinitronaphthalene". Org. Synth.; Coll. Vol. 3, p. 341 (diazodization followed by treatment with nitrite)
3. Sandin, R. B.; Cairns, T. L. (1943). "1,2,3-Triiodo-5-nitrobenzene". Org. Synth.; Coll. Vol. 2, p. 604 (diazodization followed by treatment with iodide)
4. Coleman, G. H.; Lillis, G. A.; Goheen, G. E. (1939). "Nitrosyl Chloride". Inorganic Syntheses 1: 55–59. doi:10.1002/9780470132326.ch20. This procedure generates the nitrosylsulfuric acid as an intermediate en route to NOCl.