Poly(1,3,4-oxadiozoles) via aromatic nucleophilic displacement

US5118781A · kind A · utility

Assignee

• The United States of America as represented by the Administrator of the National Aeronautics and Space Administration · US

Inventors

• John W. Connell · Newport News, US
• Paul M. Hergenrother · Yorktown, US
• Peter Wolf · Gaithersburg, US

Key dates

• Filing date: Jan 22, 1991
• Grant date: Jun 2, 1992
• Expiry date: Jan 22, 2011

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C08G73/08
• WIPO field: Macromolecular chemistry, polymers
• WIPO sector: Chemistry

Abstract

Poly(1,3,4-oxadiazoles) (POX) are prepared by the aromatic nucleophilic displacement reaction of di(hydroxyphenyl)-1,3,4-oxadiazole monomers with activated aromatic dihalides or activated aromatic dinitro compounds. The polymerizations 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)-1,3,4-oxadiazole monomers are synthesized by reacting 4-hydroxybenzoic hydrazide with phenyl-4-hydrobenzoate in the melt and also by reacting aromatic dihydrazides with two moles of phenyl-4-hydroxybenzoate in the melt. This synthetic route has provided high molecular weight POX of new chemical structure, is economically and synthetically more favorable than other routes, and allows for facile chemical structure variation due to the large variety of activated aromatic dihalides which are available.