Acetyl chloride () is an acyl chloride derived from

acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...

(). It belongs to the class of

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

s called acid halides. It is a colorless, corrosive, volatile

liquid Liquid is a state of matter with a definite volume but no fixed shape. Liquids adapt to the shape of their container and are nearly incompressible, maintaining their volume even under pressure. The density of a liquid is usually close to th ...

. Its formula is commonly abbreviated to AcCl.

Synthesis

On an industrial scale, the reaction of acetic anhydride with

hydrogen chloride The Chemical compound, compound hydrogen chloride has the chemical formula and as such is a hydrogen halide. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric water vapor. Hyd ...

produces a mixture of acetyl chloride and acetic acid: :

Laboratory routes

Acetyl chloride was first prepared in 1852 by French chemist Charles Gerhardt by treating potassium acetate with phosphoryl chloride. Acetyl chloride is produced in the laboratory by the reaction of

with chlorodehydrating agents such as phosphorus trichloride (), phosphorus pentachloride (), sulfuryl chloride (), phosgene, or thionyl chloride (). However, these methods usually give acetyl chloride contaminated by phosphorus or sulfur impurities, which may interfere with the organic reactions.

Other methods

When heated, a mixture of dichloroacetyl chloride and

gives acetyl chloride. It can also be synthesized from the catalytic carbonylation of methyl chloride.

Occurrence

Acetyl chloride is not expected to exist in nature, because contact with

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

would hydrolyze it into acetic acid and

. In fact, if handled in open air it releases white "smoke" resulting from hydrolysis due to the moisture in the air. The smoke is actually small droplets of hydrochloric acid and

formed by hydrolysis.

Uses

Acetyl chloride is used for acetylation reactions, i.e., the introduction of an acetyl group. Acetyl is an acyl group having the formula . For further information on the types of chemical reactions compounds such as acetyl chloride can undergo, see acyl halide. Two major classes of acetylations include esterification and the Friedel-Crafts reaction.

Acetic acid esters and amide

Acetyl chloride is a reagent for the preparation of esters and amides of acetic acid, used in the derivatization of

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

s and amines. One class of acetylation reactions are esterification, for example the reaction with

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

to produce ethyl acetate and

: : Frequently such acylations are carried out in the presence of a base such as pyridine, triethylamine, or DMAP, which act as catalysts to help promote the reaction and as bases neutralize the resulting HCl. Such reactions will often proceed via ketene.

Friedel-Crafts acetylations

A second major class of acetylation reactions are the Friedel-Crafts reactions.Charles Merritt, Jr and Charles E. Braun "9-Acetylanthracene" Org. Synth. 1950, 30, 2.

References

External links

* {{Authority control Acyl chlorides Acetylating agents Organic compounds with 2 carbon atoms Acetyl compounds