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
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 ...
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
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 ...
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
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 ...
. 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
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 ...
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
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 ...
:
:
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. ]
See also
*
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 ...
*
Acetyl bromide
*
Acetyl fluoride
*
Acetyl iodide
References
External links
*
{{Authority control
Acyl chlorides
Acetylating agents
Organic compounds with 2 carbon atoms
Acetyl compounds