Synthesis and Evaluation of N-Phenylalkoxyamines for Nitroxide-Mediated Polymerization

Alkoxyamines bearing an N-phenyl moiety were synthesized by the addition of carbon-centered radicals across the double bond of nitrobenzene and were subsequently tested for polymerization efficacy. Carbon-centered radicals derived fro (1-bromoethyl) benzene or 2-bromo-2-methylpropionic acid phenyl ester using a CuBr Cu(0) and PMDETA system were added to the nitroso group of nitrosobenzene to form alkoxyamines. Initiator 1 was isolated as a viscous, yellow oil in 55% yield after flash chromatography, while 2 was obtained as a white powder in 69% yield after recrystallization. The polymerization of styrene with alkoxyamine 1 was uncontrolled. The molecular weight distributions remained broad throughout a range of conversions and large discrepancies between the theoretical and calculated molecular weights were observed from low to high conversion. The calculated molecular weights were much higher than the theoretical molecular weights which indicates a low initiating efficiency.