The synthesis of a hydrocarbon-soluble organolithium anionic initiator. A gas–liquid chromatography study of the efficiency of the reaction of s-butyllithium with p-divinylbenzene

Abstract

The extent of conversion of the reaction between sec-butyllithium and p-divinylbenzene was evaluated by quantitative gas–liquid chromatography. The reaction of stoichiometric amounts of ultra-high purity sec-butyllithium with pure p-divinylbenzene at 0°C produces an anionic initiator, 1,4-bis(1-lithio-3-methylpentyl)benzene, 2, in essentially quantitative yields, with low concentrations of monofunctional impurities. Upon the addition of 10mol% excess of triethylamine to sec-butyllithium, the reaction of sec-butyllithium with p-divinylbenzene at 0°C yielded a homogeneous product with composition of 96% difunctionality and 4% monofunctionality, with the total disappearance of p-divinylbenzene as observed by GLC.The high purity 1,4-bis(1-lithio-3-methylpentyl)benzene initiator, 2, is an effective initiator for 1,3-butadiene polymerizations in hydrocarbon solvents and allows the synthesis of polybutadienes with microstructures ranging from 13% to 16% 1,2-vinyl content, as observed by 1H NMR analysis.