Novel heterocyclic poly(arylene ether ketone)s:: Synthesis and polymerization of 4-(4′-hydroxyaryl)(2H)phthalazin-1-ones with methyl groups

Based on green chemistry, a simple and efficient direct synthesis of 4-(4'hydroxyaryl)(2H)phthalazin-1-ones (2a-2f) was developed in a two-step reaction, in which the Friedel-Crafts acylation reaction of six phenols with phthalic anhydride was initially carried out and then followed by cyclization with hydrazine hydrate in good to excellent yields with high regioselectivity. A number of novel heterocyclic poly(arylene ether ketone)s were prepared conveniently from several unsymmetrical, twist, and noncoplanar phthalazinone-containing monomers (2a-2f) and an activated difluoro monomer via a N-C coupling reaction. It was very interesting that the obtained monomers and polymers exhibited diverse properties with. the variation of the number and location of the substituted methyl groups. All these polymers had a high molecular weight with M-n and eta(inh) in the range of 44,960-169,000 Da and 0.380.79 dL/g, respectively. Actually, the obtained polymers displayed excellent thermal properties with T-g's ranging from 222 to 248 degrees C and 5% weight loss temperatures in nitrogen higher than 430 degrees C. Moreover, these polymers were readily soluble in common organic solvents, such as N-methyl-2-pyrrolidone, chloroform, pyridine, and mcresol, and could be cast into flexible and colorless or nearly colorless films by spincoating or casting processes. (c) 2007 Wiley Periodicals, Inc.