in toluene byproducts: HgBr2; addn. of BBr3 in toluene to a stirred suspn. of arylmercury(II) bromide in toluene under N2, keeping at 90°C for 24 h; cooling to room temp., filtn. to remove HgBr2, removal of solvent under vacuum (room temp./2 mm Hg), distn. of residue in a bulb-to bulb distn. apparatus;