Intramolecular hydride shift polymerization by cationic mechanism III—Structure analyses of deuterated and non-deuterated poly-4-methyl-1-pentene

Abstract

Unlabelled and deuterium labelled (e.g. ▪) 4-methyl-1-pentene were polymerized by aluminium chloride catalyst in alkyl chloride at −130° and −78°C, and the structure of the products was investigated. Thus, the solid polymers were pyrolysed in high vacuum and the composition and relative distribution of gaseous fractions were determined. The oily fractions were analysed by mass spectroscopy supported by infra-red and nuclear magnetic resonance techniques. The analysis of the data indicates that cationically obtained poly-4-methyl-1-pentene consists mainly of ▪ repeat units together with considerable amounts of ▪ and ▪ units. These repeat structures suggest that the cationic polymerization of 4-methyl-1-pentene proceeds by composite hydride shift and conventional mechanisms. More particularly, the analysis of deuterated cationic poly-4-methyl-1-pentene indicates that a succession of 1 → 2 hydride shifts occur and not 1 → 3 hydride jumps. The analytical techniques are presented and the polymerization mechanisms are discussed.