v. To add one or more alkyl groups to a compound, especially by reacting with an alkylating agent
The Century Dictionary and Cyclopedia
To introduce an alkyl in place of a hydrogen atom.
Word Usage
"In the run-up to the summer driving season, an increased amount of propylene at oil refineries is diverted into the manufacture of high-octane alkylate gasoline, leaving less available for polypropylene production."