Phenacyl chloride, also commonly known as chloroacetophenone, is a substituted acetophenone. It is a useful building block in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

. Apart from that, it has been historically used as a riot control agent, where it is designated CN. It should not be confused with

cyanide In chemistry, cyanide () is an inorganic chemical compound that contains a functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. Ionic cyanides contain the cyanide anion . This a ...

, 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 Carl Graebe in 1871 by passing chlorine into boiling acetophenone. Phenacyl chloride is readily available and was first prepared by chlorination of acetophenone vapour. It may also be synthesized by the Friedel-Crafts acylation of

benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...

using

chloroacetyl chloride Chloroacetyl chloride is a chlorinated acyl chloride. It is a bifunctional compound, making it a useful building block chemical. Production Industrially, it is produced by the carbonylation of methylene chloride, oxidation of vinylidene chlo ...

, with an

aluminium chloride Aluminium chloride, also known as aluminium trichloride, is an inorganic compound with the formula . It forms a hexahydrate with the formula , containing six water molecules of hydration. Both the anhydrous form and the hexahydrate are col ...

catalyst: : Preparation of phenacyl chloride

Riot control agent

It was investigated, but not used, during the First and

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

s (it was used as a "green agent" by the former Japanese military during the Sino-Japanese War). Because of CN's significantly greater toxicity, CN has largely been supplanted for military use by

CS gas The compound 2-chlorobenzalmalononitrile (also called ''o''-chlorobenzylidene malononitrile; chemical formula: C10H5ClN2), a cyanocarbon, is the defining component of the lachrymatory agent commonly referred to as CS gas, a tear gas which ...

. Even though CN is still supplied to

paramilitary A paramilitary is a military that is not a part of a country's official or legitimate armed forces. The Oxford English Dictionary traces the use of the term "paramilitary" as far back as 1934. Overview Though a paramilitary is, by definiti ...

and police forces in a small pressurized aerosol known as “ Mace” or

tear gas Tear gas, also known as a lachrymatory agent or lachrymator (), sometimes colloquially known as "mace" after the Mace (spray), early commercial self-defense spray, is a chemical weapon that stimulates the nerves of the lacrimal gland in the ey ...

, CN's use is falling because

pepper spray Pepper spray, oleoresin capsicum spray, OC spray, capsaicin spray, mace, or capsicum spray is a Tear gas, lachrymator (tear gas) product containing as its active ingredient the chemical compound capsaicin, which irritates the eyes with burning ...

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 A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

with tear-gas sprays in the same way that

Kleenex Kleenex is a brand name primarily known for their line of facial tissues. Often used informally as a genericized trademark for facial tissue, ''Kleenex'' is a registered trademark of Kimberly-Clark applied to products made in 78 countries. The ...

has become strongly associated with

facial tissue Facial tissue and paper handkerchief refers to a class of soft, absorbent, disposable papers that are suitable for use on the face. They are disposable alternatives for cloth handkerchiefs. The terms are commonly used to refer to the type of tis ...

s (a phenomenon known as a

genericized trademark A generic trademark, also known as a genericized trademark or proprietary eponym, is a trademark or brand name that, because of its popularity or significance, has become the generic term for, or synonymous with, a general class of products or ...

). Like CS gas, this compound irritates the

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...

s (oral, nasal,

conjunctiva In the anatomy of the eye, the conjunctiva (: conjunctivae) is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with gobl ...

l and tracheobronchial). Sometimes it can give rise to more generalized reactions such as syncope, temporary loss of balance and orientation. More rarely, cutaneous irritating outbreaks have been observed and allergic contact permanent

dermatitis Dermatitis is a term used for different types of skin inflammation, typically characterized by itchiness, redness and a rash. In cases of short duration, there may be small blisters, while in long-term cases the skin may become thickened ...

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

asphyxia Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects all the tissues and organs, some more rapidly than others. There are m ...

TRPA1 Transient receptor potential cation channel, subfamily A, member 1, also known as transient receptor potential ankyrin 1, TRPA1, or The Mustard and Wasabi Receptor, is a protein that in humans is encoded by the ''TRPA1'' (and in mice and rats by ...

(Transient Receptor Potential-Ankyrin 1) ion channel expressed on

nociceptors A nociceptor (; ) is a sensory neuron that responds to damaging or potentially damaging stimuli by sending "possible threat" signals to the spinal cord and the brain. The brain creates the sensation of pain to direct attention to the body part, ...

(especially

trigeminal In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chewing ...

) has been implicated as the site of action for CN, in vivo and in vitro.doi=10.1016/j.taap.2008.04.005

References

External links

* {{DEFAULTSORT:Phenacyl Chloride Acetophenones Aromatic ketones Lachrymatory agents Organochlorides Riot control agents