Nitrosyl chloride

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Nitrosyl chloride
Preferred IUPAC name

Nitrosyl chloride[citation needed]

Systematic name

Nitrooyl chloride[citation needed]

Other names

  • Nitrogen oxychloride[citation needed]
  • Nitrosonium chloride[citation needed]
  • Tildens Reagent[citation needed]

Identifiers
CAS number 2696-92-6 YesY
PubChem 17601
ChemSpider 16641 YesY
EC number 220-273-1
UN number 1069
MeSH nitrosyl+chloride
RTECS number QZ7883000
Jmol-3D images Image 1
Properties
Molecular formula NOCl
Molar mass 65.459 g mol−1
Appearance Yellow gas
Density 2.872 mg mL−1
Melting point −59.4 °C; −74.9 °F; 213.8 K
Boiling point −5.55 °C; 22.01 °F; 267.60 K
Solubility in water Reacts
Structure
Molecular shape Dihedral, digonal
Hybridisation sp2 at N
Dipole moment 1.90 D
Thermochemistry
Std enthalpy of
formation ΔfHo298		 51.71 kJ mol−1
Standard molar
entropy So298		 261.68 J K-1 mol−1
Hazards
MSDS inchem.org
NFPA 704
0
3
1
W
Related compounds
Related compounds
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Nitrosyl chloride is the chemical compound NOCl. It is a yellow gas that is most commonly encountered as a decomposition product of aqua regia, a mixture of hydrochloric acid and nitric acid. The related nitrosyl halides nitrosyl fluoride, NOF, and nitrosyl bromide, NOBr, are also known.

Structure and synthesis

The molecule is bent. A double bond exists between N and O (distance = 1.16 Å) and a single bond between N and Cl (distance = 1.69 Å). The O-N-Cl angle is less than 180°.[1]

Production

As a simple, stable molecule, NOCl can be prepared in many ways. NOCl forms by the direct combination of chlorine and nitric oxide; this reaction reverses above 100 °C. Alternatively, nitrosylsulfuric acid and HCl also affords the compound:

HCl + NOHSO4 → NOCl + H2SO4

This method is used industrially.[2] A more convenient laboratory method involves the (reversible) dehydration of nitrous acid by HCl[3]

Michael Faraday prepared nitrosyl chloride by reacting palladium with aqua regia:

Pd + HNO3 + 3 HCl → PdCl2 + ClNO + 2 H2O

Another method of producing nitrosyl chloride is by direct union of the elements at 400 °C:

N2 + O2 + Cl2 → 2 ClNO

Occurrence in aqua regia

NOCl also arises from the combination of hydrochloric and nitric acids according to the following reaction:[4]

HNO3 + 3 HCl → Cl2 + 2 H2O + NOCl

In nitric acid, NOCl is readily oxidized into nitrogen dioxide. The presence of NOCl in aqua regia was described by Edmund Davy in 1831.[5]

Reactions

NOCl behaves as an electrophile and an oxidant in most of its reactions. With halide acceptors, for example antimony pentachloride, converts to nitrosonium salts:

NOCl + SbCl5 → [NO]+[SbCl6]-

In a related reaction, sulfuric acid gives nitrosylsulfuric acid, the mixed acid anhydride of nitrous and sulfuric acid:

ClNO + H2SO4 → ONHSO4 + HCl

NOCl reacts with silver thiocyanate to give silver chloride and the pseudohalogen nitrosyl thiocyanate:

ClNO + AgSCN → AgCl + ONSCN

Applications in organic synthesis

Aside from its role in the production of caprolactam, NOCl finds some other uses In organic synthesis. It adds to alkenes to afford α-chloro oximes.[6] The initial addition of NOCl follows the Markovnikov rule. Ketenes also add NOCl, giving nitrosyl derivatives:

CH2C=C=O + NOCl → ONCH2C(O)Cl

Propylene oxide also undergoes electrophilic addition with NOCl to give an α-chloro-nitritoakyl derivative:

At ambient temperatures, NOCl converts cyclic amines to the alkenes. For example, aziridine reacts with NOCl to give ethene, nitrous oxide and hydrogen chloride.

Industrial applications

NOCl and cyclohexane react photochemically to give cyclohexanone oxime hydrochloride. This process exploits the tendency of NOCl to undergo photodissociation into NO and Cl radicals. The oxide is converted to caprolactam, a precursor to Nylon-6.[2]

Safety

Nitrosyl chloride is very toxic and irritating to the lungs, eyes, and skin.

References

  1. ↑ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  2. ↑ 2.0 2.1 Josef Ritz, Hugo Fuchs, Heinz Kieczka, William C. Moran "Caprolactam" Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a05_031
  3. ↑ J. R. Morton, H. W. Wilcox "Nitrosyl Chloride" Inorganic Syntheses 1953, vol. 48-52. doi:10.1002/9780470132357.ch16
  4. ↑ L. J. Beckham, W. A. Fessler, M. A. Kise (1951). "Nitrosyl Chloride". Chemical Reviews 48 (3): 319–396. doi:10.1021/cr60151a001. 
  5. ↑ Edmund Davy (1830 - 1837). Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London, Vol. 3. JSTOR. pp. 27–29. JSTOR 110250.  Unknown parameter |titel= ignored (help);
  6. ↑ Ohno, M,; Naruse, N.; Terasawa, I. (1973), "7-cyanoheptanal", Org. Synth. ; Coll. Vol. 5: 266 
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