To address the insolubility problem of polyketones, we used an approach to high molecular weight wholly aromatic polyketones without ether linkages via soluble precursors derived from isophthaldehyde-based bis(aminonitrile)s. Polymerization of bis(α-aminonitrile)s with activated dihalides using NaH as base in DMF yielded soluble, high molecular weight poly(aminonitrile)s, which were hydrolyzed in acidic conditions to produce the corresponding aromatic polyketones without ether linkages or alkyl substituents in the polymeric backbones. These polyketones displayed excellent thermal properties and solvent resistance. For the synthesis of poly(aminonitrile)s and polyketones containing ether linkages in the polymeric backbone, only low to medium molecular weight polymers were obtained. Model studies proved that the carbanions of the aminonitriles reacted with ether linkages to form more stable phenoxide anions and cause the termination of the polymerization.

To address the insolubility problem of polyketones, we used a new approach to high molecular weight wholly aromatic polyketones without ether linkages via soluble precursors derived from isophthaldehyde-based amino nitriles. 1 High molecular weight, soluble poly(amino nitrile)s 2 were synthesized from the anions of these bis(amino nitrile)s 1 and 4,4′-difluorobenzophenone using sodium hydride as base under mild reaction conditions. Hydrolysis of the poly(amino nitrile)s under acidic conditions yielded the corresponding polyketone, poly(p-phenylenecarbonyl-p-phenylenecarbonyl-mphenylenecarbonyl) (3). This all aromatic polyketone, with an absence of ether linkages in the polymer backbone, displays excellent thermal properties and solvent resistivity. It is infusible and insoluble in most common organic solvents.

Very efficient syntheses of “long” bisphenol and activated dihalide monomers containing keto groups were developed on the basis of α-aminonitrile chemistry. Known and novel activated dihalide monomers were obtained in quantitative yields and without isomeric impurities. This method is suitable for any activated dihalide by reaction with 2 equiv of the anion of p-fluorobenzalaminonitrile (8), followed by hydrolysis to produce a monomer with two more p-fluorobenzoyl units. Similarly, use of the anion of p-methoxybenzalaminonitrile (15) by reaction with activated dihalides provides a general route to bisphenols. Less expensive dichloro monomers, e.g., 4,4‘-dichlorobenzophenone, can be used to synthesize these “long” bisphenol and activated dihalide monomers.

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