Oxidation of natural rubber using a sodium tungstate/acetic acid/hydrogen peroxide catalytic system

摘要: Abstract A catalytic system based on Na 2 WO 4 /CH 3 COOH/H O effectively oxidizes natural rubber (NR) to prepare telechelic epoxidised liquid (TELNR). The possesses a much higher epoxidation efficiency than the traditional CH system: degree ( X epoxy ) of products increases from merely 5.6% (CH values as high 52.1% (Na by reacting for 24 h at 60 °C. Moreover, this also induces hydrolytic degradation so that weight average molecular M w ¯ NR decreases, e.g., 14.10 × 10 5 Da 0.57 × 10 (TELNR) after 30 h. process probably proceeds via mononuclear tungsten peroxo-species with coordinated peracetyl/acetyl group, suggested ESI-MS measurements. During oxidation, tungstic anion [W(CH COOO)(O)(O ] − not only catalyzes epoxidation, but further oxidation groups form ketones and aldehydes.