My watch list  

Nitrosyl chloride

Nitrosyl chloride

Systematic name Nitrosyl chloride
Other names Nitrogen oxychloride
Nitrosonium chloride
Molecular formula ClNO
Molar mass 65.46 g/mol
Appearance yellow gas, red liquid
CAS number [2696-92-6]
Density and phase liq: 1.417 g/cm3 (-12 °C)
gas: 2.99 g/L
Solubility in water decomposes
Other solvents chlorocarbons
Melting point -59.6 °C (? K)
Boiling point -6.4 °C (? K)
Molecular shape sp2 at N
Dipole moment 1.90 D
MSDS External MSDS
Main hazards highly toxic
NFPA 704
R/S statement R: ?
S: ?
RTECS number  ?
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data IR 1800 (νNO), 596, 332 cm-1
Related compounds
Related compounds NO
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and 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

Although its formula is written NOCl, the structure is better represented ONCl. 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 113°.[1]

NOCl can be prepared by the direct combination of chlorine and nitric oxide. Alternatively, nitrosylsulfuric acid and HCl also affords the compound:

HCl + NOHSO4 → NOCl + H2SO4

It also arises from the combination of hydrochloric and nitric acids according to the following reaction:[2]

HNO3 + 3 HCl → Cl2 + 2 H2O + NOCl

Although this mixture was used for dissolving gold for a long time the first description of the gas was done by Edmund Davy in 1831.[3]


  • NOCl reacts with halide acceptors to give the nitrosyl cation, [NO]+. This species is available as NOBF4.
  • NOCl reacts with water to release HCl.
  • Heating NOCl above 100 C gives back Cl2 and NO.
  • In organic synthesis, NOCl is often employed. It adds to alkenes to afford α-chloro oximes.[4]


NOCl is toxic and irritating to the lungs.


  1. ^ Holleman, A. F.; Wiberg, E. "Inorganic Chemistry" Academic Press: San Diego, 2001. ISBN 0-12-352651-5.
  2. ^ L. J. Beckham, W. A. Fessler, M. A. Kise (1951). "Nitrosyl Chloride". Chemical Reviews 48: 319-396. doi:10.1021/cr60151a001.
  3. ^ Edmund Davy (1830 - 1837). "Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London, Vol. 3.": 27-29.
  4. ^ Ohno, M,; Naruse, N.; Terasawa, I. " 7-cyanoheptanal" Organic Syntheses, Collected Volume 5, page.266 (1973). (addition of NOCl to cyclooctene)
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Nitrosyl_chloride". A list of authors is available in Wikipedia.
Your browser is not current. Microsoft Internet Explorer 6.0 does not support some functions on Chemie.DE