Crosslinking and ageing of 13C labelled polyisoprene part 1: Synthesis and polymerisation of 4-13C-isoprene
Résumé
4-13C-isoprene was prepared by the Wittig reaction. All reaction steps were optimised using unlabelled compounds. By reaction with triphenyl phosphine, 13C labelled methyl iodide afforded labelled methyltriphenyl phosphine iodide in 84% yield. This reacted with meth acrolein with production of 4-13Cisoprene in 64% yield. Labelled polyisoprene was prepared by anionic polymerisation initiated by t-butyl lithium. Based on 13CH3I the overall yield is ca 30%. The polymer was characterized by 1H and 13C NMR spectroscopy. The contribution of each microstructure was [cis 1-4, 72%]; [trans 1-4, 10%]; [3-4, 18%].