Useful model systems for the study of S(RN)1 chemistry in the synthesis of poly(arylene ether ketone)s

Factors contributing to the occurrence of the S(RN)1 reaction during the synthesis of poly(arylene ether ketone)s are studied using a variety of analytical techniques. Product analysis of polymerization reactions and magnetic resonance studies on photochemical model systems were performed. The polymerization of 4,4'-dichlorobenzophenone with 4,4'-isopropyiidenediphenol under basic conditions was run in four amide solvents: 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU), 1-methyl-2-pyrrolidinone (NMP), 1,1,3,3-tetramethylurea (TMU) and N,N'-dimethylacetamide (DMAc). Molecular weights of the products followed the order M(n)(DMAc) > M(n)(NMP) > M(n)(TMU) > M(n)(DMPU). Simulations of time-resolved electron paramagnetic resonance (TREPR) spectra were used to identify the radicals produced by photoinduced hydrogen atom abstraction in each of the four solvents. Transient optical absorption was used to quantify the yield of radicals produced by reaction of triplet benzophenone-d(10) with each solvent. Time-of-flight secondary ion mass spectrometry of the resulting oligomers showed evidence for hydrogen-terminated chain ends. Solvated electrons were observed from the photoionization of phenolates using TREPR. The relevance of this to single electron transfer events in these solvents, or with certain aryl halide monomers for polymer synthesis, is discussed.