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Phenacyl chloride




IUPAC nameExpression error: Unexpected > operator.
CAS Number
532-27-4 YesY
ChemSpider 10303 N
Jmol 3D model Interactive image
PubChem 10757
Chemical formula
Molar mass 154.59 g·mol−1
Density 1.324 g/cm3
Boiling point
Solubility in water
EU classification (DSD)
Toxic T
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oilHealth code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gasReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Phenacyl chloride is a substituted acetophenone. It is a useful building block in organic chemistry. Apart from that, it has been historically used as a riot control agent, where it is designated CN.


Phenacyl chloride is readily available commercially. It may be synthesized by the Friedel-Crafts acylation of benzene using chloroacetyl chloride, with an aluminium chloride catalyst:[1]

Preparation of phenacyl chloride.png

Riot control agent[]

It was investigated, but not used, during the First and Second World Wars.

Because of its significantly greater toxicity,[2] it has largely been supplanted by CS gas. Even though CN is still supplied to paramilitary and police forces in a small pressurized aerosol known as “Mace” or tear gas, its use is falling as pepper spray both works and disperses more quickly than CN.

The term "Mace" came into being because it was the brand-name invented by one of the first American manufacturers of CN aerosol sprays. Subsequently, Mace became synonymous with tear-gas sprays in the same way that Kleenex has become strongly associated with tissue papers (a phenomenon known as a genericized trademark).[citation needed]

Like CS gas, this compound irritates the mucous membranes (oral, nasal, conjunctival and tracheobronchial). Sometimes it can give rise to more generalized reactions such as syncope, temporary loss of balance and orientation.[2] More rarely, cutaneous irritating outbreaks have been observed and allergic contact permanent dermatitis.[3]

At high concentrations CN has caused corneal epithelial damage and chemosis. It has also accounted for at least five deaths, which have resulted from pulmonary injury and/or asphyxia.[4]


  1. "ω-Chloroisonitrosoacetophenone". 1955. ; "Coll. Vol.". pp. 191. 
  2. 2.0 2.1 Ballantyne, B.; Swanston, D. W. (1978). "The comparative acute mammalian toxicity of 1-chloroacetophenone (CN) and 2-chlorobenzylidene malononitrile (CS)". pp. 75–95. Digital object identifier:10.1007/BF01891962. PMID 350195. 
  3. doi:10.1046/j.1365-2133.1999.02724.x
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  4. Blain, P. G. (2003). "Tear Gases and Irritant Incapacitants: 1-Chloroacetophenone, 2-Chlorobenzylidene Malononitrile and Dibenz[b,f]-1,4-Oxazepine". pp. 103–110. PMID 15071820. 

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