Acetyl Chloride

[75-36-5] C2H3ClO (MW 78.50) InChI = 1S/C2H3ClO/c1-2(3)4/h1H3 InChIKey = WETWJCDKMRHUPV-UHFFFAOYSA-N (useful for electrophilic acetylation of arenes,2 alkenes,2a,3 alkynes,4 saturated alkanes,3a,5 organometallics, and enolates (on C or O);6 for cleavage of ethers;7 for esterification of sterically unhindered8 or acid-sensitive9 alcohols; for generation of solutions of anhydrous hydrogen chloride in methanol;10 as a dehydrating agent; as a solvent for organometallic reactions;11 for deoxygenation of sulfoxides;12 as a scavenger for chlorine13 and bromine;14 as a source of ketene; and for nucleophilic acetylation15) Physical Data: bp 51.8 °C;1a mp −112.9 °C;1a d 1.1051 g cm−3;1a refractive index 1.38976.1b IR (neat) ν 1806.7 cm−1;16 1H NMR (CDCl3) δ 2.66 ppm; 13C NMR (CDCl3) δ 33.69 ppm (q) and 170.26 ppm (s); the bond angles (determined by electron diffraction17) are 127.5° (OCC), 120.3° (OCCl), and 112.2° (ClCC). Analysis of Reagent Purity: a GC assay for potency has been described;18 to check qualitatively for the presence of HCl, a common impurity, add a few drops of a solution of crystal violet in chloroform;19 a green or yellow color indicates that HCl is present, while a purple color that persists for at least 10 min indicates that HCl is absent.1b Preparative Methods: treatment of Acetic Acid or sodium acetate with the standard inorganic chlorodehydrating agents (PCl3,1b,23 SO2Cl2,1a,24 or SOCl21b,25) generates material that may contain phosphorus- or sulfur-containing impurities.1b,23a,26 Inorganic-free material can be prepared by treatment of HOAc with Cl2CHCOCl (Δ; 70%),27 PhCOCl (Δ; 88%),28 PhCCl3 (cat. H2SO4, 90 °C; 92.5%),29 or phosgene30 (optionally catalyzed by DMF,30e magnesium or other metal salts,30a,b,d or activated carbon30b,c), or by addition of hydrogen chloride to acetic anhydride (85–90 °C; ‘practically quantitative’).1a,31 Purification: HCl-free material can be prepared either by distillation from dimethylaniline11c,20 or by standard degassing procedures.20c,21 Handling, Storage, and Precautions: acetyl chloride should be handled only in a well-ventilated fume hood since it is volatile and toxic via inhalation.22 It should be stored in a sealed container under an inert atmosphere. Spills should be cleaned up by covering with aq sodium bicarbonate.1a