Investigations into the AIBN initiation steps in the free radical polymerisation of acrylonitrile by the aminoxyl trapping technique

Summary

A modification of the radical trapping technique employing the stable nitroxide 1,1,3,3-tetramethyl-2,3-dihydro-1 H-isoindol-2-yloxyl, has been used to study the reaction of cyanoisopropyl radicals with acrylonitrile. By keeping the concentration of the aminoxyl radical very low (strategically added via a syringe pump), the addition of acrylonitrile to cyanoisopropyl radicals becomes competitive with radical trapping. Thus, sufficient quantities of alkoxyamines produced by the trapping of ‘second generation’ carboncentred radicals (cyanoisopropyl plus one monomer unit), and even ‘third generation’ carbon-centred radicals were obtained for identification by HPLC/MS techniques. Trapping by traces of adventitious oxygen was also competitive and the various peroxy radicals thus formed, underwent addition to acrylonitrile followed by further reaction or trapping by the aminoxyl. *** DIRECT SUPPORT *** AEB03077 00003