Crosslinking and ageing of 13C labelled polyisoprene part 1: Synthesis and polymerisation of 4-13C-isoprene

Abstract 4- 13 C-isoprene was prepared by the Wittig reaction. All reaction steps were optimised using unlabelled compounds. By reaction with triphenyl phosphine, 13 C labelled methyl iodide afforded labelled methyl-triphenyl phosphine iodide in 84% yield. This reacted with meth acrolein with production of 4- 13 C-isoprene in 64% yield. Labelled polyisoprene was prepared by anionic polymerisation initiated by t- butyl lithium. Based on 13 CH 3 I the overall yield is ca 30%. The polymer was characterized by 1 H and 13 C NMR spectroscopy. The contribution of each microstructure was [ cis 1-4, 72%]; [ trans 1-4, 10%]; [3-4, 18%].