What does allyl mean?
Allyl is a technical term from organic chemistry denoting the univalent group CH₂=CH–CH₂–, a fragment of the propene molecule in which one hydrogen atom has been removed from the saturated end. As a substituent, the allyl group appears in a wide range of compounds — allyl alcohol, allyl chloride, and allyl sulfide among them — many of which are important industrial intermediates or, as in garlic and mustard oils, sources of strong flavors and odors. The word is used almost exclusively in scientific writing and is typically attached attributively to another noun, as in 'allyl group'. Its name derives from the Latin allium, meaning garlic, a tribute to the fact that the group was first identified in garlic oil. Related adjective forms such as 'allylic' describe structures or reactions involving this group. Though obscure outside the laboratory, allyl is a useful word for anyone reading chemistry, food science, or perfumery literature, where it labels one of the most familiar and reactive building blocks in organic synthesis.
nounA univalent organic group or radical, CH₂=CH–CH₂–, derived from propene by removal of a hydrogen atom from the saturated carbon; it occurs as a substituent in many organic compounds.
- The univalent chemical group CH₂=CH–CH₂–, derived from propene, that forms part of many organic compounds.
- A substituent or radical of this structure when attached to a larger molecule, as in allyl alcohol or allyl chloride.
"The pungent aroma of garlic comes largely from compounds containing an allyl group."
"Allyl chloride is an important industrial intermediate in the manufacture of glycerol and epichlorohydrin."
"Many of the sulfur compounds responsible for garlic's characteristic odor contain an allyl group."
The plural is rare and appears mainly in technical contexts referring to multiple allyl groups or compounds.
"The extract contains several allyls responsible for its sharp flavor."
The word 'allyl' comes from the Latin for garlic — because chemists first isolated this group from garlic oil, the very source of garlic's famous smell.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of allyl
The word allyl was coined in the mid-nineteenth century from the Latin allium, meaning 'garlic', because chemists first isolated the group from compounds in garlic oil (allyl sulfide). It entered scientific usage through German chemical literature before spreading into English. It shares its root with other allium-derived terms such as alliaceous ('garlic-like') and the botanical genus name Allium.
Related word forms
How allyl is actually used
Strictly a technical term used in organic chemistry and related sciences; it is rarely encountered in general conversation. It is almost always used attributively before another noun (e.g. 'allyl group', 'allyl compound') rather than standing alone.
Easily confused with allyl
An ally is a person or nation that supports or cooperates with another, while allyl (with an -l) is a chemical group in organic chemistry.