:Acetyl chloride
{{short description|Organic compound (CH₃COCl)}}
{{Distinguish|Chloroacetic acid|Chloroacetyl chloride|Acetylcholine|Actinium(III) chloride}}
{{Chembox
| Watchedfields = changed
| verifiedrevid = 477239934
| Reference=Merck Index, 11th Edition, 79.
| Name = Acetyl chloride
| ImageFileL1 = Acetyl-chloride_skeletal.svg
| ImageClassL1 = skin-invert-image
| ImageNameL1 = Skeletal formula of acetyl chloride
| ImageFileR1 = Acetyl-chloride-3D-balls.png
| ImageClassR1 = bg-transparent
| ImageNameR1 = Ball-and-stick model of acetyl chloride
| ImageFile2 = Acetyl-chloride-3D-vdW.png
| ImageClass2 = bg-transparent
| ImageSize2 = 120px
| ImageName2 = Space-filling model of acetyl chloride
| ImageFile3 = Acetyl chloride 25ml.jpg
| PIN = Acetyl chloride{{cite book | title = Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book) | publisher = The Royal Society of Chemistry | date = 2014 | location = Cambridge | pages = 796–797 | doi = 10.1039/9781849733069-FP001 | isbn = 978-0-85404-182-4}}
| SystematicName = Ethanoyl chloride
| OtherNames = Acyl chloride
|Section1={{Chembox Identifiers
| CASNo = 75-36-5
| CASNo_Ref = {{cascite|correct|CAS}}
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 37580
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 6127
| DrugBank = DB14623
| EC_number = 200-865-6
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = QD15RNO45K
| Beilstein = 605303
| Gmelin = 1611
| PubChem = 6367
| RTECS = AO6390000
| UNNumber = 1717
| InChI = 1/C2H3ClO/c1-2(3)4/h1H3
| InChIKey = WETWJCDKMRHUPV-UHFFFAOYAQ
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C2H3ClO/c1-2(3)4/h1H3
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = WETWJCDKMRHUPV-UHFFFAOYSA-N
| SMILES = ClC(=O)C
}}
|Section2={{Chembox Properties
| Formula = {{chem2|CH3COCl}}
| MolarMass = 78.49 g/mol
| Appearance = Colorless liquid
| Density = 1.104 g/ml, liquid
| Solubility = Reacts with water
| MeltingPtC = -112
| BoilingPtC = 52
| MagSus = −38.9·10−6 cm3/mol
| Viscosity =
}}
|Section3={{Chembox Structure
| Dipole = 2.45 D
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| GHSSignalWord = Danger
| GHSPictograms = {{GHS02}}{{GHS05}}{{GHS07}}
| HPhrases = {{H-phrases|225|302|314|335|412}}
| PPhrases = {{P-phrases|210|233|240|241|242|243|260|261|264|270|271|273|280|301+312|301+330+331|303+361+353|304+340|305+351+338|310|312|321|330|363|370+378|403+233|403+235|405|501}}
| NFPA-H = 3
| NFPA-F = 3
| NFPA-R = 2
| NFPA-S= w
| FlashPtC = 4
| AutoignitionPtC = 390
| ExploLimits = 7.3–19%
}}
|Section8={{Chembox Related
| OtherFunction_label = acyl chlorides
| OtherFunction = Propionyl chloride
Butyryl chloride
| OtherCompounds = Acetic acid
Acetic anhydride
Acetyl bromide
}}
}}
Acetyl chloride ({{chem2|CH3COCl}}) is an acyl chloride derived from acetic acid ({{chem2|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:{{Ullmann |doi=10.1002/14356007.a01_045|title=Acetic Acid|year=2000|last1=Cheung|first1=Hosea|last2=Tanke|first2=Robin S.|last3=Torrence|first3=G. Paul|isbn=3527306730}}
:{{chem2 | (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.See:
- Gerhardt, Charles (1852) [https://babel.hathitrust.org/cgi/pt?id=uva.x002457938;view=1up;seq=128 "Ueber wasserfreie organische Säuren"] (On anhydrous organic acids), Annalen der Chemie und Pharmacie, 83 : 112–116.
- Gerhardt, Charles (1853) [https://babel.hathitrust.org/cgi/pt?id=chi.44985506;view=1up;seq=67 "Untersuchungen über die wasserfreien organischen Säuren"] (Investigations into anhydrous organic acids), Annalen der Chemie und Pharmacie, 87 : 57–84; see especially pp. 68–71.
Acetyl chloride is produced in the laboratory by the reaction of acetic acid with chlorodehydrating agents such as phosphorus trichloride ({{chem2|PCl3}}), phosphorus pentachloride ({{chem2|PCl5}}), sulfuryl chloride ({{chem2|SO2Cl2}}), phosgene, or thionyl chloride ({{chem2|SOCl2}}). However, these methods usually give acetyl chloride contaminated by phosphorus or sulfur impurities, which may interfere with the organic reactions.{{cite book| title = Handbook of Reagents for Organic Synthesis, Activating Agents and Protective Groups| chapter = Acetyl chloride| author1 = Leo A. Paquette| publisher = John Wiley & Sons| year = 2005| isbn = 978-0-471-97927-2| page = 16}}
=Other methods=
When heated, a mixture of dichloroacetyl chloride and acetic acid gives acetyl chloride. It can also be synthesized from the catalytic carbonylation of methyl chloride.{{cite patent|country=US|number=4352761|title=Production of acetyl chloride|pubdate=1982-10-05
|inventor1-last=Erpenbach |inventor1-first=Heinz
|inventor2-last=Gehrmann |inventor2-first=Klaus
|inventor3-last=Lork |inventor3-first=Winfried
|inventor4-last=Pring |inventor4-first=Peter
|assign=Hoechst AG
}}
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 {{chem2|\sC(\dO)\sCH3}}. 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:
:{{chem2 | CH3COCl + HO\sCH2\sCH3 -> CH3\sCOO\sCH2\sCH3 + 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.Charles Merritt, Jr and Charles E. Braun "9-Acetylanthracene" Org. Synth. 1950, 30, 2. {{doi|10.15227/orgsyn.030.0001}}
See also
References
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