Acetyl chloride

Acetyl chloride
IUPAC name	Ethanoyl chloride
Other names	Acetyl chloride
Identifiers
CAS number	75-36-5
RTECS number	AO6390000
SMILES	CC(=O)Cl
Properties
Molecular formula	CH3COCl
Molar mass	78.5 g/mol
Appearance	colorless liquid
Density	1.11 g/ml, liquid
Melting point	−112 °C
Boiling point	51 °C
Solubility in water	Reacts
Structure
Dipole moment	2.45 D
Hazards
EU classification	Flammable (F) Corrosive (C)
R-phrases	R11, R14, R34
S-phrases	(S1/2), S9, S16, S26, S45
Flash point	5 °C
Autoignition temperature	390 °C
Explosive limits	7.3–19%
Related Compounds
Related acyl chlorides	Propionyl chloride Butyryl chloride
Related compounds	Acetic acid Acetic anhydride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Acetyl chloride, also known as ethanoyl chloride, is an acid chloride (also known as an acyl chloride) derived from acetic acid (ethanoic acid). It has the formula CH₃COCl and it belongs to the class of organic compounds called acyl halides. At room temperature and pressure, it is a clear colorless liquid. Acetyl chloride does not exist in nature, because contact with water would hydrolyze it into acetic acid and hydrogen chloride. In fact, if handled in open air it gives of white smoke owing to the hydrolysis from the moisture in the air. The smoke is actually gaseous hydrogen chloride which forms small droplets in the air with water vapour.

Synthesis

Acetyl chloride is synthesized by the reaction of acetic acid (CH₃COO-H) with thionyl chloride (O=SCl₂) under liberation of sulfur dioxide (SO₂).

CH₃COO-H + O=SCl₂ → CH₃COCl + SO₂ + H-Cl

Uses

It is a reagent for acetylation in the synthesis or derivatization of chemical compounds. Examples of acetylation reactions include acylation processes such as esterification (see below) and the Friedel-Crafts reaction).

CH₃COCl + HO-CH₂-CH₃ → CH₃-COO-CH₂-CH₃ + H-Cl

Frequently such acylations are carried out in the presence of a base such as pyridine, triethylamine, or DMAP, which as catalysts help to promote the reaction and as bases neutralize the resulting HCl.

Acetylation is the introduction of an acetyl group via acylation using a reactant such as acetyl chloride or acetic anhydride. An acetyl group is an acyl group having the formula

-C(=O)-CH₃

For further information on the types of chemical reactions compounds such as acetyl chloride can undergo, see acyl halide.

External links

• International Chemical Safety Card 0210

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