No abstract

Polymerization of isobutylene in n-hexane at -78 ~ initiated by MeCOBr. AIBr 3 was studied. The results obtained were compared with the corresponding data for RCOX-2A1Br 3 complexes (R = Me or Ph, X = CI or Br). The main peculiarities of the polymerization mechanism under the action of MeCOBr'AIBr3 were established. The rate constants of proton elimination and of chain termination and chain growth were determined experimentally.

The polymerization of isobutylene in hexane at -78 ~ in the presence of the MeCOBr-AIBr 3 + PhCOCI-AIBr 3 and MeCOBr-2AIBr 3 + PhCOC]-2AIBr 3 mixtures was investigated. It was established that only acetyl bromide shows an initiating activity, while benzoyl chloride seems to be part of a counterion, which markedly increases the "viability" of growing carbocationic centers. Possible mechanisms for the formation of initiating centers in mixed complexes are discussed.