Nitrosyl chloride

Nitrosyl chloride
Preferred IUPAC name Nitrosyl chloride
Systematic name Nitrooyl chloride
Other names Nitrogen oxychloride Nitrosonium chloride Tildens Reagent
Identifiers
CAS number	2696-92-6 Y
PubChem	17601 Y
ChemSpider	16641 Y
EC number	220-273-1
UN number	1069
MeSH	Nitrosyl+chloride
RTECS number	QZ7883000
Jmol-3D images	Image 1
SMILES ClN=O
InChI InChI=1S/ClNO/c1-2-3 Y Key: VPCDQGACGWYTMC-UHFFFAOYSA-N Y InChI=1S/ClNO/c1-2-3 Key: VPCDQGACGWYTMC-UHFFFAOYSA-N InChI=1/ClNO/c1-2-3 Key: VPCDQGACGWYTMC-UHFFFAOYAB
Properties
Molecular formula	ClNO
Molar mass	65.46 g/mol
Appearance	yellow gas, red liquid
Density	1.273 g/cm3 (liquid, -12 °C) 2.872 g/L (gas)
Melting point	-59.4 °C
Boiling point	-5.55 °C
Solubility in water	decomposes
Solubility in chlorocarbons	soluble
Structure
Molecular shape	sp2 at N
Dipole moment	1.90 D
Hazards
MSDS	ICSC 1580
EU Index	Not listed
Main hazards	Highly toxic
NFPA 704	0 3 1 W
Related compounds
Other anions	Nitrosyl fluoride Nitrosyl bromide
Other cations	Thionyl chloride
Related compounds	Nitric oxide Nitrosylsulfuric acid Nitrosonium tetrafluoroborate Thionitrosyl chloride
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 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

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°.

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:

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.

Reactions

• 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.
• NOCl photolyses to NO and a Cl radical.

Safety

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