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 t he synthesis of poly(arylene ether ketone)s are studied using a variet y of analytical techniques. Product analysis of polymerization reactio ns and magnetic resonance studies on photochemical model systems were performed. The polymerization of 4,4'-dichlorobenzophenone with 4,4'-i sopropyiidenediphenol under basic conditions was run in four amide sol vents: 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU), 1-me thyl-2-pyrrolidinone (NMP), 1,1,3,3-tetramethylurea (TMU) and N,N'-dim ethylacetamide (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 use d to identify the radicals produced by photoinduced hydrogen atom abst raction in each of the four solvents. Transient optical absorption was used to quantify the yield of radicals produced by reaction of triple t benzophenone-d(10) with each solvent. Time-of-flight secondary ion m ass spectrometry of the resulting oligomers showed evidence for hydrog en-terminated chain ends. Solvated electrons were observed from the ph otoionization of phenolates using TREPR. The relevance of this to sing le electron transfer events in these solvents, or with certain aryl ha lide monomers for polymer synthesis, is discussed.