title: Acetoxy group
text: # Acetoxy group
  
  In organic chemistry, the acetoxy group (abbr. AcO or OAc; IUPAC name: acetyloxy), is a functional group with the formula $−OCOCH_3$ and the structure $−O−C(=O)−CH_3.$ As the -oxy suffix implies, it differs from the acetyl group $(−C(=O)−CH_3)$ 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):
  
  * Acetyl halide, such as acetyl chloride in the presence of a base like triethylamine
  * Activated ester form of acetic acid, such as a N-hydroxysuccinimide ester, although this is not advisable due to higher costs and difficulties.
  * Acetic anhydride in the presence of base with a catalyst such as pyridine with a bit of DMAP added.
  
  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.
  
  ### Alcohol deprotection
  
  For deprotection (regeneration of the alcohol)
  
  * Aqueous base (pH >9)
  * Aqueous acid (pH <2), may have to be heated
  * 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)
  