To a suitable vessel containing about 16.2 g of an approximate 50:50 mixture of methyl α-chloro-o-toluate and methyl α-bromo-o-toluate is added 100 ml of acetonitrile and 17.2 g (0.085 mol) of tributylphosphine and held at reflux under nitrogen for about 45 minutes. The solvent is removed under vacuum and the residue is dissolved in 370 ml of water. The aqueous solution is extracted twice with ether and added to a solution of 102 g (1.0 mol) of sodium bromide in 150 ml of water. This mixture is extracted with three 150 ml portions of chloroform. The chloroform extracts are combined, dried over calcium sulfate and concentrated under vacuum to 36.3 g of colorless oil. Two triturations of this oil with ether provides a white solid which upon recrystallization from ethyl acetate-ether yields approximately 24.6 g of o-methoxycarbonylbenzyltributylphosphonium bromide having a melting point of 65°-66°.
