Acetyl group ($\mathrm{C}{\mathrm{H}}_3\mathrm{C}(=\mathrm{O})-$)

An acetyl group is the acyl unit $\mathrm{C}{\mathrm{H}}_3\mathrm{CO}-$. Its point of attachment lies at the carbonyl carbon, distinguishing it from an ethyl group or an acetate ion.

Transfer of an acetyl group changes a substrate's covalent structure. In biology, acetyl-CoA can supply such units, while acetylation of an amino group can alter charge and molecular recognition.