Acetyl chloride
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acetyl chloride
(ə′sed·əl ′klö′rīd)
(organic chemistry) CH3COCl A colorless, fuming liquid with a boiling point of 51-52°C; soluble in ether, acetone, and acetic acid; used in organic synthesis, and in the manufacture of dyestuffs and pharmaceuticals.
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Acetyl chloride
| Acetyl chloride[1] | |
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Acetyl chloride |
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Other names
Ethanoyl chloride |
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| Identifiers | |
| CAS number | 75-36-5  |
| ChemSpider | 6127 |
| UNII | QD15RNO45K |
| ChEBI | CHEBI:37580 |
| RTECS number | AO6390000 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | CH3COCl |
| Molar mass | 78.49 g/mol |
| Appearance | colorless liquid |
| Density | 1.104 g/ml, liquid |
| Melting point |
-112 °C, 161 K, -170 °F |
| Boiling point |
52 °C, 325 K, 126 °F |
| 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 |
| Autoignition temperature |
390 °C |
| Explosive limits | 7.3–19% |
| Related compounds | |
| Related acyl chlorides | Propionyl chloride Butyryl chloride |
| Related compounds | Acetic acid Acetic anhydride Acetyl bromide |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Acetyl chloride, CH3COCl, also known as ethanoyl chloride or acyl chloride, is an acid chloride derived from acetic acid. It belongs to the class of organic compounds called acyl halides. It is a 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 off white smoke owing to the hydrolysis from the moisture in the air. The "smoke" is actually small droplets of hydrochloric acid formed by hydrolysis.
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Contents
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Synthesis
The usual method involves the reaction of acetic acid with standard inorganic chlorodehydrating agents, such as by using PCl3, PCl5, SO2Cl2, or SOCl2. However, this usually gives acetyl chloride which is contaminated by phosphorus or sulfur impurities, which may interfere with the organic reactions.[2]
It is produced by the reaction of hydrogen chloride with acetic anhydride:[3]
- (CH3CO)2O + HCl → CH3COCl + CH3CO2H
HCl impurities can be removed by distilling the crude product from dimethylaniline or by degassing the mixture by a stream of argon.
It may also be synthesized from the catalytic carbonylation of methyl chloride.[4]
Heating dichloroacetic chloride with acetic acid also gives acetyl chloride in 70% yield.[2]
Uses
It is a chemical for acetylation in the synthesis or derivatization of organic 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 act as catalysts to help promote the reaction and as bases neutralize the resulting HCl. Such reactions will often proceed via ketene.
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.
References
- ^ Merck Index, 11th Edition, 79.
- ^ a b Leo A. Paquette (2005). "Acetyl chloride". Handbook of Reagents for Organic Synthesis, Activating Agents and Protective Groups. John Wiley & Sons. p. 16. ISBN 978-0-471-97927-2.
- ^ Hosea Cheung, Robin S. Tanke, G. Paul Torrence “Acetic Acid” in Ullmann's Encyclopedia of Industrial Chemistry 2002, Wiley-VCH, Weinheim. doi:10.1002/14356007.a01_045
- ^ US 4352761
External links
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