Naming a branched alkane step 2. identify and name the branches on the longest continuous chain. • names of branches (alkyl groups) are derived from the name of the alkane with the same number of carbons by replacing the suffix "ane" with "yl." e. g., -ch2-ch2-ch3 is propane - ane + yl = propyl • when multiple branches are present they are named in alphabetical order (e. g. butylmethyl, not methylbutyl). the name for this branch is