The Dow Chemical Company

Luke R Kleiss

Ming-Biann Liu

Steven Rosenberg

William J Harris

Zenon Lysenko

Richard C Krauss

Salts that contain AA-PBZ monomer ions and BB-PBZ monomer ions can be precipitated from an aqueous solution by contacting soluble salts of the monomers in an aqueous solution. The monomer salt can be polymerized by ordinary techniques to form polybenzazole polymers without the need for devolatilization and with very accurate stoichiometric control.

Salts of polybenzazole monomers and their use

PBZ polymers are synthesized by the reaction of AA- and BB-monomers. The BB-monomer is conveniently synthesized and isolated as a phosphate salt having a uniform number of phosphate ions associated with each BB-monomer ion. Such high purity monophosphate and diphosphate salts can be obtained by precipitating the monomer from an aqueous acid solution by adjusting the pH balance or from a mixture of phosphoric acid and a volatile, polar, saturated organic liquid at a relatively low temperature.

Phosphate salts of monomers for PBZ and their use in preparing PBZ

An aminophenolic compound can be synthesized by contacting a halo-nitro-phenolic compound, such as 2-chloro-4,6-dinitrorescorcinol, with a hydrogenating agent, such as hydrogen, and a catalyst, such as palladium-on-carbon, in an aqueous solution in the presence of an acid such as phosphoric acid.

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Lisle, IL, United States of America

Luke R Kleiss