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

The model compound N,C-diphenylnitrone [N-(benzylidene)aniline-N-oxide] (3) was prepared by condensation of benzaldehyde with phenylhydroxylamine to s tudy its thermal stability. X-ray diffraction analysis of a single crystal established the conformation of the nitrone group. A new monomer 4-(methacr yloyloxy)benzaldehyde-phenylnitrone (8) was also prepared and could not be polymerized with 2,2'-azobisisobutyronitrile (AIBN) as initiator at 70 degr ees C. Under these conditions the nitrone reacted exclusively in an intermo lecular 1,3-dipolar cycloaddition to give oligomeric tetrahydro-1,2-oxazoli ne derivates. The kinetics of the cycloaddition was investigated. Additiona lly, different (meth)acryl- and styryl-substituted aldehyde monomers were s ynthesized: N-(2-methacryloyloxyethyl)-N-ethyl-4-aminobenzaldehyde (19a), N -(2-acryloyloxyethyl)-N-ethyl-4-aminobenzaldehyde (19b), 2-(N'-ethyl-4-form ylanilino)ethyl N-(alpha,alpha-dimethyl-3-isopropenylbenzyl)carbamate (20) and 4-(3-methacryloyloxypropoxy)benzaldehyde (25). These new monomers were homo- and copolymerized with MMA radically at 70 degrees C using AIBN as in itiator. The resulting polyaldehydes 26-30 were reacted with phenylhydroxyl amine 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 .