In
organic chemistry, the acetoxy group (abbr. AcO or OAc;
IUPAC name: acetyloxy[1]), is a
functional group with the
formula−OCOCH3 and the
structure−O−C(=O)−CH3. As the -oxy suffix implies, it differs from the
acetyl group (−C(=O)−CH3) by the presence of an additional
oxygen atom. The name acetoxy is the short form of acetyl-oxy.
Functionality
An acetoxy group may be used as a protection for an alcohol functionality in a synthetic route although the protecting group itself is called an
acetyl group.
Alcohol protection
There are several options of introducing an acetoxy functionality in a molecule from an alcohol (in effect protecting the alcohol by
acetylation):
An alcohol is not a particularly strong
nucleophile and, when present, more powerful nucleophiles like
amines will react with the above-mentioned reagents in preference to the alcohol.[5]
Anhydrous base such as sodium
methoxide in methanol. Very useful when a methyl
ester of a carboxylic acid is also present in the molecule, as it will not hydrolyze it like an aqueous base would. (Same also holds with an ethoxide in ethanol with ethyl esters)[8]
^Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge:
The Royal Society of Chemistry. 2014. p. 805.
doi:
10.1039/9781849733069-00648.
ISBN978-0-85404-182-4. The systematic name 'acetyloxy' is preferred to the contracted name 'acetoxy' that may be used in general nomenclature.