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AssigneeThe United States of America as represented by the United States National Aeronautics and Space Administration
InventorsJohn W. Connell, Paul M. Hergenrother, Peter Wolf
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Poly(1,2,4-triazoles)(PT) have been prepared by involving the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)-1,2,4-triazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The reactions are carried out in polar aprotic solvents such as sulfolane or diphenylsulfone using alkali metal bases such as potassium carbonate at elevated temperatures under nitrogen. The di(hydroxyphenyl)-1,2,4-triazole monomers are first synthesized by reacting bis(4-hydroxyphenyl) hydrazide with aniline hydrochloride at 250.degree. C. in the melt and also by reacting 1,3 or 1,4-bis-(4-hydroxyphenyl)phenylenedihydrazide with 2 moles of aniline hydrochloride in the melt. Purification of the di(hydroxyphenyl)-1,2,4-triazole monomers is accomplished by recrystallization. This synthetic route has provided high molecular weight PT of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the availability of a large variety of activated aromatic dihalides.
A poly(1,2,4-triazole) consisting of repeating units having the following general structural formula ##STR10## wherein the substitution of oxygen is selected from the group consisting of:
A process for synthesizing poly(1,2,4-triazoles) by aromatic nucleophilic displacement, which comprises reacting a di(hydroxyphenyl)-1,2,4-triazole having the general structural formula ##STR16## wherein the substitution of the hydroxy radicals is selected from the group consisting of:
Dependencies are inferred from the claim text.