Use of controlled radical polymerization of butadiene with AIBN and TEMPO for the determination of the NMR characteristics of hydroxymethyl groups

The controlled radical polymerization of butadiene initiated with 2,2'-azoi sobutyronitrile (AIBN) and in the presence of 2,2,6,6-tetramethylpiperidine -N-oxyl (TEMPO) is presented. The produced oligomers which have number aver age degrees of polymerization ranging between 3 and 12 were characterized b y NMR. This led to the determination of both the end-groups and the functio nality. The hydrolysis of these oligomers yields alpha-hydroxy-omega-cyano- polybutadiene. C-13 and H-1 NMR spectra of these products exhibit two chara cteristic signals of hydroxymethyl groups. The mechanism of the polymerizat ian allows the assignments to cis- and trans-CH2CH=CH-CH2OH groups. In fact , this method also shows that geraniol end groups are negligible in commerc ially available products obtained by the polymerization initiated with hydr ogen peroxide.