One of the types of reactions I'm doing in college are nucleophilic substitution on polyfluorinated benzene rings with 2 electron withdrawing substitutions and how I'm doing it is by adding lithium to an alcohol to convert it into a nucleophilic alkoxide ion, the idea being that the oxygen atom will displace one of the fluorine atoms. The reaction works great (proceeds at room temp., takes ~30 min, excellent yields). I'm just wondering what the mechanism is. The wiki page lists 6 types of nucleophilic substitutions but I don't know which category my reaction falls into.