Acyl is a chemical group derived from a carboxylic acid by removal of the hydroxyl group, commonly attached to other molecules to form acyl derivatives such as acyl chlorides or esters. In biochemistry and organic chemistry, it designates a carbonyl-containing substituent (R-CO–) that participates in acylation reactions. It is pronounced as two syllables, with the emphasis typically on the first: /ˈæsɪl/ in many contexts, though scientific readings may vary slightly in stress depending on adjacent terms.
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