What does ethanoyl mean?
Ethanoyl is the systematic chemical name for the monovalent acyl group CH3CO–, the fragment also known as acetyl. It is what remains when the hydroxyl group is removed from ethanoic, or acetic, acid, and it occurs widely in organic chemistry as a substituent attached to a carbon, oxygen, sulfur, or other atom. In practice, ethanoyl is encountered in systematic compound names and reaction descriptions, while acetyl remains especially familiar in pharmaceuticals and biochemical terminology. The distinction is one of naming rather than chemistry: ethanoyl and acetyl designate the same group. Calling it ethanoyl is therefore useful when emphasizing systematic nomenclature or distinguishing it from related groups such as methanoyl and benzoyl. The word is technical rather than general vocabulary, and its concise formula represents a small but fundamental building block of carboxylic-acid chemistry.
nounThe monovalent acyl group CH3CO−, derived from ethanoic acid and also known as the acetyl group. In organic chemistry, it functions as a substituent by attaching through its carbonyl carbon.
- The acyl group CH3CO−, formally named ethanoyl and conventionally called the acetyl group.
"The reaction proceeds by attaching an ethanoyl group to the aromatic ring."
"The reaction proceeds by attaching an ethanoyl group to the aromatic ring."
"The compound is converted into ethanoyl chloride before it is treated with the nucleophile."
Rare; writers usually say ethanoyl groups when referring to more than one instance of this chemical group.
"The polymer chain bears several ethanoyls along its backbone."
Ethanoyl is acetyl's systematic name: the compact CH3CO– building block that helps form many familiar organic molecules.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does ethanoyl come from?
Ethanoyl belongs to modern systematic organic nomenclature and is formed from the stem ethan-, found in ethane and ethanoic acid, together with the acyl-forming suffix -oyl. The construction developed as part of the systematic naming of organic groups during the 20th century. Its older equivalent, acetyl, was formed from Latin acetum, the source of the acetic root shared with acetate.
How ethanoyl is actually used
This is specialist chemical vocabulary, most often encountered in systematic compound names and reaction descriptions. It is standard in international nomenclature, while acetyl is particularly familiar in biological, pharmaceutical, and general organic-chemistry usage.
Easily confused with ethanoyl
Ethanoyl is the acyl group CH3CO−, whereas ethanol is the alcohol CH3CH2OH.