Phenacyl chloride, also commonly known as chloroacetophenone, 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.[5] It should not be confused with
cyanide, another agent used in chemical warfare, which has the chemical structure CN−. Chloroacetophenone is thermally stable, and is the only tear agent that is distillable at ambient conditions.
Preparation
Chloroacetophenone was first synthetized by Graebe in 1871 by passing chlorine into boiling
acetophenone.[6]
It was investigated, but not used, during the
First and
Second World Wars (it was used as a "green agent" by the former Japanese military during the Sino-Japanese War).
Because of its significantly greater toxicity,[9] 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 and is less toxic 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, in the United States, Mace became
synonymous with tear-gas sprays in the same way that
Kleenex has become strongly associated with
facial tissues (a phenomenon known as a
genericized trademark).
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.[9] More rarely, cutaneous irritating outbreaks have been observed and allergic contact permanent
dermatitis.[5]
TRPA1 (Transient Receptor Potential-Ankyrin 1) ion channel expressed on
nociceptors (especially
trigeminal) has been implicated as the site of action for CN, in vivo and in vitro. [11][12]
^
abBallantyne, B.; Swanston, D. W. (1978). "The comparative acute mammalian toxicity of 1-chloroacetophenone (CN) and 2-chlorobenzylidene malononitrile (CS)". Archives of Toxicology. 40 (2): 75–95.
doi:
10.1007/BF01891962.
PMID350195.
S2CID35150415.
^Blain, P. G. (2003). "Tear Gases and Irritant Incapacitants: 1-Chloroacetophenone, 2-Chlorobenzylidene Malononitrile and Dibenz[b,f]-1,4-Oxazepine". Toxicological Reviews. 22 (2): 103–110.
doi:
10.2165/00139709-200322020-00005.
PMID15071820.
S2CID21164652.