The suitability of several dilithio compds. as initiators for the anionic polymn. of dienes was tested in view of the following criteria: quant. reaction of diolefins with sec-BuLi [598-30-1] within reasonable periods of time, pptn. of dilithio compds. in a heptane-PhMe mixt., sufficient soly. of the dilithio compds. in PhMe, rapid initiation of polymn. and small dispersion index of the polymer, and low cost of the prepn. of the diolefins and the dilithio initiators. The bifunctional initiator derived from 1,4-bis(4-(1-phenylvinyl)phenyl)butane [54378-46-0] was most suited for the prepn. of diene blocks in ABA triblock copolymers.