Polymeric nitrones, 1. Synthesis and modification of polymeric nitrones derived from polymerizable aldehydes

Abstract

The model compound N,C-diphenylnitrone[N-(benzylidene)aniline-N-oxide] (3) was prepared by condensation of benzaldehyde with phenylhydroxylamine to study its thermal stability. X-ray diffraction analysis of a single crystal established the conformation of the nitrone group. A new monomer 4-(methacryloyloxy)benzaldehyde-phenylnitrone (8) was also prepared and could not be polymerized with 2,2′-azobisisobutyronitrile (AIBN) as initiator at 70°C. Under these conditions the nitrone reacted exclusively in an intermolecular 1,3-dipolar cycloaddition to give oligomeric tetrahydro-1,2-oxazoline derivates. The kinetics of the cycloaddition was investigated. Additionally, different (meth)acryl- and styryl-substituted aldehyde monomers were synthesized: N-(2-methacryloyloxyethyl)-N-ethyl-4-aminobenzaldehyde (19 a), N-(2-acryloyloxyethyl)-N-ethyl-4-aminobenzaldehyde (19 b), 2-(N′-ethyl-4-formylanilino)ethyl N-(α,α-dimethyl-3-isopropenylbenzyl)carbamate (20) and 4-(3-methacryloyloxypropoxy)benzaldehyde (25). These new monomers were homo- and copolymerized with MMA radically at 70°C using AIBN as initiator. The resulting polyaldehydes 26–30 were reacted with phenylhydroxylamine to obtain the polynitrones 31–35 in yields of up to 95%. The obtained highly polar polynitrones 31–32 were modified by irradiation with UV-light.