Acetyl chloride

Acetyl chloride^[1]
Skeletal formula of acetyl chloride	Ball-and-stick model of acetyl chloride
Names
	Preferred IUPAC name Acetyl chloride
	Systematic IUPAC name Ethanoyl chloride
	Other names Acyl chloride
Identifiers
CAS Number	75-36-5 ;
3D model (JSmol)	Interactive image;
Beilstein Reference	605303
ChEBI	CHEBI:37580 ;
ChemSpider	6127 ;
ECHA InfoCard	100.000.787
EC Number	200-865-6;
Gmelin Reference	1611
PubChem CID	6367;
RTECS number	AO6390000;
UNII	QD15RNO45K ;
UN number	1717
CompTox Dashboard (EPA)	DTXSID2023852 ;
	InChI InChI=1S/C2H3ClO/c1-2(3)4/h1H3 Key: WETWJCDKMRHUPV-UHFFFAOYSA-N ; InChI=1/C2H3ClO/c1-2(3)4/h1H3 Key: WETWJCDKMRHUPV-UHFFFAOYAQ;
	SMILES ClC(=O)C;
Properties
Chemical formula	CH3COCl
Molar mass	78.49 g/mol
Appearance	Colorless liquid
Density	1.104 g/ml, liquid
Melting point	−112 °C (−170 °F; 161 K)
Boiling point	52 °C (126 °F; 325 K)
Solubility in water	Reacts with water
Magnetic susceptibility (χ)	-38.9·10−6 cm3/mol
Structure
Dipole moment	2.45 D
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H225, H302, H314, H335, H412
Precautionary statements	P210, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P273, P280, P301+P312, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P330, P363, P370+P378, P403+P233, P403+P235, P405, P501
NFPA 704 (fire diamond)	3 3 2 W
Flash point	4 °C (39 °F; 277 K)
Autoignition; temperature	390 °C (734 °F; 663 K)
Explosive limits	7.3–19%
Related compounds
Related acyl chlorides	Propionyl chloride; Butyryl chloride
Related compounds	Acetic acid; Acetic anhydride; Acetyl bromide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Acetyl chloride (CH₃COCl) is an acyl chloride derived from acetic acid (CH₃COOH). It belongs to the class of organic compounds called acid halides. It is a colorless, corrosive, volatile liquid. Its formula is commonly abbreviated to AcCl.

Synthesis

On an industrial scale, the reaction of acetic anhydride with hydrogen chloride produces a mixture of acetyl chloride and acetic acid:^[3]

(CH₃CO)₂O + HCl → CH₃COCl + CH₃CO₂H

Laboratory routes

Acetyl chloride was first prepared in 1852 by French chemist Charles Gerhardt by treating potassium acetate with phosphoryl chloride.^[4]

Acetyl chloride is produced in the laboratory by the reaction of acetic acid with chlorodehydrating agents such as phosphorus trichloride (PCl₃), phosphorus pentachloride (PCl₅), sulfuryl chloride (SO₂Cl₂), phosgene, or thionyl chloride (SOCl₂). However, these methods usually give acetyl chloride contaminated by phosphorus or sulfur impurities, which may interfere with the organic reactions.^[5]

Other methods

When heated, a mixture of dichloroacetyl chloride and acetic acid gives acetyl chloride.^[5] It can also be synthesized from the catalytic carbonylation of methyl chloride.^[6]

Occurrence

Acetyl chloride is not expected to exist in nature, because contact with water would hydrolyze it into acetic acid and hydrogen chloride. 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 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 −C(=O)−CH₃. 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 alcohols and amines. One class of acetylation reactions are esterification, for example the reaction with ethanol to produce ethyl acetate and hydrogen chloride:

CH₃COCl + HO−CH₂−CH₃ → CH₃−COO−CH₂−CH₃ + HCl

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.^[7]

References

^ Merck Index, 11th Edition, 79.
^ Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 796–797. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
^ Cheung, Hosea; Tanke, Robin S.; Torrence, G. Paul (2000). "Acetic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_045. ISBN 3527306730.
^
See:
- Gerhardt, Charles (1852) "Ueber wasserfreie organische Säuren" (On anhydrous organic acids), Annalen der Chemie und Pharmacie, 83 : 112–116.
- Gerhardt, Charles (1853) "Untersuchungen über die wasserfreien organischen Säuren" (Investigations into anhydrous organic acids), Annalen der Chemie und Pharmacie, 87 : 57–84; see especially pp. 68–71.
^ ^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.
^ US 4352761, Erpenbach, Heinz; Gehrmann, Klaus & Lork, Winfried et al., "Production of acetyl chloride", published 1982-10-05, assigned to Hoechst AG
^ Charles Merritt, Jr and Charles E. Braun "9-Acetylanthracene" Org. Synth. 1950, 30, 2. doi:10.15227/orgsyn.030.0001

External links

International Chemical Safety Card 0210

[1] Merck Index, 11th Edition, 79.

[iupac2013-2] Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 796–797. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.

[3] Cheung, Hosea; Tanke, Robin S.; Torrence, G. Paul (2000). "Acetic Acid". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a01_045. ISBN 3527306730.

[4] See:
Gerhardt, Charles (1852) "Ueber wasserfreie organische Säuren" (On anhydrous organic acids), Annalen der Chemie und Pharmacie, 83 : 112–116.

Gerhardt, Charles (1853) "Untersuchungen über die wasserfreien organischen Säuren" (Investigations into anhydrous organic acids), Annalen der Chemie und Pharmacie, 87 : 57–84; see especially pp. 68–71.

[5] Gerhardt, Charles (1852) "Ueber wasserfreie organische Säuren" (On anhydrous organic acids), Annalen der Chemie und Pharmacie, 83 : 112–116.

[6] Gerhardt, Charles (1853) "Untersuchungen über die wasserfreien organischen Säuren" (Investigations into anhydrous organic acids), Annalen der Chemie und Pharmacie, 87 : 57–84; see especially pp. 68–71.

[HdBook-5] 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.

[6] US 4352761, Erpenbach, Heinz; Gehrmann, Klaus & Lork, Winfried et al., "Production of acetyl chloride", published 1982-10-05, assigned to Hoechst AG

[7] Charles Merritt, Jr and Charles E. Braun "9-Acetylanthracene" Org. Synth. 1950, 30, 2. doi:10.15227/orgsyn.030.0001

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