Acetyl iodide is an organoiodine compound

Organoiodine compound

Organoiodine compounds are organic compounds that contain one or more carbon–iodine bonds. They occur widely in organic chemistry, but are relatively rare in nature...

 wth the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 CH₃C(O)I. It is a colourless liquid. It is formally derived from acetic acid

Acetic acid

Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...

. Although far rarer in the laboratory than the related acetyl bromide

Acetyl bromide

Acetyl bromide is an acyl bromide compound. As is expected, it may be prepared by reaction between phosphorus tribromide and acetic acid:...

 and acetyl chloride

Acetyl chloride

Acetyl chloride, CH3COCl, also known as ethanoyl chloride or acyl chloride, is an acid chloride derived from acetic acid. It belongs to the class of organic compounds called acyl halides. It is a colorless liquid. Acetyl chloride does not exist in nature, because contact with water would hydrolyze...

, acetyl iodide is produced, transiently at least, on a far larger scale than any acid halide. Specifically, it is generated by the carbonylation

Carbonylation

Carbonylation refers to reactions that introduce carbon monoxide into organic and inorganic substrates. Carbon monoxide is abundantly available and conveniently reactive, so it is widely used as a reactant in industrial chemistry.-Organic chemistry:...

 of methyl iodide in the Cativa

Cativa process

The Cativa process is a method for the production of acetic acid by the carbonylation of methanol. The technology, which is similar to the Monsanto process, was developed by BP Chemicals and is under license by BP Plc...

 and Monsanto process

Monsanto process

The Monsanto process is an important method for the manufacture of acetic acid by catalytic carbonylation of methanol. This process operates at a pressure of 30–60 atm and a temperature of 150–200 °C and gives a selectivity greater than 99%. It was developed 1960 by German BASF and...

es that are the main industrial route to acetic acid. It is also an intermediate in the production of acetic anhydride from methyl acetate

Methyl acetate

Methyl acetate, also known as MeOAc, acetic acid methyl ester or methyl ethanoate, is a carboxylate ester with the formula CH3COOCH3. It is normally a flammable liquid with a characteristic, pleasant smell like certain glues or nail polish removers. Methyl acetate has characteristics very similar...

.

Upon treatment with carboxylic acids, acetyl iodide does not exhibit reactions typical of acyl halides, say acetyl chloride. Instead acetyl iodide undergoes iodide/hydroxide exchange with most carboxylic acid

Carboxylic acid

Carboxylic acids are organic acids characterized by the presence of at least one carboxyl group. The general formula of a carboxylic acid is R-COOH, where R is some monovalent functional group...

s:

CH₃C(O)I + RCO₂H → CH₃CO₂H + RC(O)I