Contribution à l'étude de la métallation de structures polyisoprène, 1. Mèthode de dosage

Squalene, as a model compound, and polyisoprene were metalated by the complex of sec-butyllithium (sec-BuLi) with N,N,N′,N′-tetramethylenediamine. The rate of metalation was determined indirectly by further reaction with a deactivating reagent. Amongst the various agents tested, a solution of chlorotrimethylsilane (Me₃SiCl) in diethyl ether was preferred, as deactivation by this reagent does not lead to secondary reactions. The rate of silylation of sec-BuLi by Me₃SiCl was found to be influenced by the solvent and the temperature. The presence of diethyl ether, as solvent of silylation, and a reaction temperature of 0°C are suitable conditions for the reaction between lithiated polymers and Me₃SiCl.