INVESTIGATION OF THE INITIATION REACTION OF ISOPRENE POLYMERIZATION WITH 2-ETHYLHEXYLSODIUM IN HEPTANE

The kinetics of the initiation of isoprene polymerization in heptane w ith the hydrocarbon-soluble alkylsodium compound 2-ethylhexylsodium wa s studied. Initiation rates were estimated from the induction period a nd by measuring UV spectra of polyisoprenyl-sodium (lambda(max) = 304 nm) during the course of polymerization. The initiation reaction is fi rst order in initiator both in the course of the reaction and with res pect to the starting concentration of the initiator. The same result i s obtained when 2-ethylhexyllithium is used. The initiation rate const ants are: k(i) = 1,6.10(-3) and 5,5.10(-4) L/(mol.s) for sodium and li thium compounds at 26 degrees C, respectively. Aggregated forms of org anoalkali compounds are suggested to take part in the initiation react ion of isoprene polymerization.