OCOCH3

OCOCH3 denotes the acetoxy or acetyloxy group, an ester functional group derived from acetic acid. It represents an oxygen atom linked to a carbonyl carbon that bears a methyl group, giving the structural motif -O-CO-CH3. When this group is attached to another molecule, the entire substituent is commonly referred to as an acetoxy group.

In organic chemistry, OCOCH3 appears in acetate esters. These are typically formed by acetylating a hydroxyl group with acetic anhydride or acetyl chloride, yielding RO-COCH3 (an acetyl ester) and a corresponding byproduct such as acetic acid. The acetoxy substituent is often written as acetoxy or AcO in shorthand nomenclature.

Applications and examples: acetates are widely used as protecting groups for alcohols in multistep synthesis, because the acetoxy group can be introduced under mild conditions and removed under selective hydrolysis. A well-known example is aspirin (acetylsalicylic acid), in which an acetoxy group is installed on a phenolic hydroxyl of salicylic acid. Acetylation also occurs in natural products and drug molecules to modify polarity, metabolic stability, or biological activity.

Reactivity: acetyl esters can be hydrolyzed to yield the corresponding alcohol and acetic acid under acidic or basic conditions, and they can be cleaved by enzymes (esterases) in biological systems to release acetate. As protecting groups, their installation and removal are strategic steps in organic synthesis.

See also: acetate, ester, acetyl group, protecting group.