In organic chemistry, an acyl chloride (or acid
chloride) is an organic compound with the functional
group –COCl. i.e
O
ǁ
R– C – Cl Functional group
When naming acid chloride the first step is to
select the longest chain containing maximum
number of carbon atoms.
 If you have something substituted into the
hydrocarbon chain, the carbon in the -COCl
group counts as the number 1 carbon.
 The “e” of alkanes is replaced by the suffix
“OYL” and then chloride is added to it.
Ethane becomes Ethanoyl chloride
Propane becomes Propanoyl acid.
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Name the following compound.
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From Phosphorus pentachloride PCl5:
Phosphorus(V) chloride reacts with carboxylic acids to give
steamy acidic fumes of hydrogen chloride and a liquid mixture
of the acyl chloride and a phosphorus compound, phosphorus
trichloride oxide (phosphorus oxychloride) - POCl3.The acyl
chloride can be separated by fractional distillation.

From Thionyl dichloride:
Sulphur dichloride oxide (thionyl chloride) reacts with
carboxylic acids to produce an acyl chloride, sulphur dioxide
and hydrogen chloride gases are given off.

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Acyl chlorides like ethanoyl chloride are colourless fuming
liquids.
Acyl chlorides can't be said to dissolve in water because they
react (often violently) with it.
Their boiling points are high as compared to the alkanes of the
same size but lower as compared to corresponding alcohols.
Acid chlorides does not form hydrogen bonding.

Reaction with water:
Adding an acyl chloride to water produces the corresponding
carboxylic acid together with steamy acidic fumes of hydrogen
chloride.

Reaction with phenol:
An acid chloride like ethanoyl chloride reacts with phenol to
give phenyl ethanoate and hydrogen chloride.
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Acid chlorides are widely used in the plastics and
polymers industries.
They are also used in the production of pesticides.