-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.