Selective mono-allylation of diphenyl ether with allyl bromide catalyzed by lead halo composite (Pb3BrF5/Pb3ClF5)

Allylation of diphenyl ether (DPO) with allyl bromide (ABr) was catalyzed b y lead halo composite of the general formula Pb3XF5 (where X = Br or Cl) at 80 degreesC. The reaction was carried out in a stirred glass reactor at at mospheric pressure with ABr and DPO (molar ratio of ABr:DPO = 1:5) which ga ve mainly para-allyl DPO. Side reactions like isomerization of the double b ond and cyclization of allylic functional groups were observed when allyl b romide was taken in excess. These products were p-l-propenyl DPO 'oxepane', ortho- and para-monoallyl DPO's and p,p'-diallyl DPO. However, under the o ptimized reaction conditions, the allylation was more selective for para-al lyl DPO. This implies that functional selectivity which is difficult to ach ieve in most cases, could be easily achieved with solid lead halo composite catalysts. (C) 2000 Published by Elsevier Science B.V.