Nitrosylsulfuric acid

Nitrosylsulfuric acid
Names
	IUPAC name Nitrosylsulfuric acid
	Other names nitrosonium bisulfate, chamber crystals
Identifiers
CAS Number	7782-78-7 ;
3D model (JSmol)	Interactive image;
ChemSpider	74147 ;
ECHA InfoCard	100.029.058
PubChem CID	82157;
CompTox Dashboard (EPA)	DTXSID30889380 ;
	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
	Occupational safety and health (OHS/OSH):
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 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.

^ 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.
^ Hodgson, H. H.; Mahadevan, A. P.; Ward, E. R. (1955). "1,4-Dinitronaphthalene". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 3, p. 341. (diazodization followed by treatment with nitrite)
^ Sandin, R. B.; Cairns, T. L. (1943). "1,2,3-Triiodo-5-nitrobenzene". Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 2, p. 604. (diazodization followed by treatment with iodide)
^ 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.

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