You have been employed by a biochemist, Fungus P. Gildersleeve, who has given you a very expensive sample of benzoic acid labeled equally in both oxygens with 18O. He asks you to prepare methyl benzoate (structure in Eq. 20.16, p. 965), preserving as much 18O label in the ester as possible. Which method of ester synthesis would you choose to carry out this assignment? Why?