Studies on Dilithium Initiators. 4. Effect of Structure Variations

New double 1,1-diphenylethylene (DDPU) compounds with different substituent groups on 1,3-bis(1-phenylethenyl)benzene (PUB) and samples of 1,3-bis[1-(methylphenyl)ethenyl]benzene (MPUB) with different methyl group positions on the phenyl rings were prepared. Included in the preparation was also a non-DDPU diolefinic compound in which the center phenyl ring of PUB was replaced by a saturated one. The behavior of isoprene polymerization initiated by the dilithium initiators obtained by the addition reaction of s-BuLi with these diolefinic compounds was studied. The slow propagation from the initial initiator-isoprene adduct observed for the initiators based on PUB and MPUB was not affected by any of the structural variations