Basic hydrolysis of 1,4 bis(triphenylphosphonio)buta 1,3 diene dichloride with 10% NaOH gave isomeric 4 diphenylphosphoryl 4 phenylbut 1(2) enes and 1 diphenylphosphoryl 1 phe nylbuta 1,3 diene, the products of anionotropic migration of a phenyl group from the P atom to the α position. Hydrolysis with Na 2 CO 3 afforded only the diene product. In both cases, triphe nylphosphine and triphenylphosphine oxide were isolated as secondary products. Dehydro chlorination of 2 chloro 1,4 bis(triphenylphosphonio)but 2 ene dibromide with triphenylphos phine was proposed as a new convenient route to 1,4 bis(triphenylphosphonio)buta 1,3 diene dibromide.