The building blocks of English

Affixes

-yl

Also ‑oyl.

Forming names of chemical radicals.

Greek hulē, material, matter.

Examples include acetyl, the radical CH₃CO- derived from acetic acid; benzyl, the C₆H₅CH₂‑ group from toluene; carbonyl, the CO- group; ethyl, the C₂H₅‑ group from ethane; hydroxyl, the -OH group; methyl, the CH₃‑ group from methane; and phenyl, the C₆H₅‑ group from benzene.

The ending ‑oyl forms the names of acid radicals from associated carboxylic acids, whose names end in ‑oic: benzoyl from benzoic acid, caproyl from caproic acid, pantoyl from pantanoic acid.

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