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.
聚(
1,3,4-噁二唑)(POX)是通过将二(羟基苯基)-
1,3,4-噁二唑单体与活性芳香族二卤化物或活性芳香族二
硝基化合物进行芳香族亲核取代反应制备而成。聚合反应在极性无
水溶剂中进行,如
苯并噻吩或二苯基砜,使用碱
金属基团,如
碳酸钾,在氮气下高温下进行。二(羟基苯基)-
1,3,4-噁二唑单体通过在熔融状态下将
4-羟基苯
肼和苯基-
4-羟基苯酸酯反应,以及通过在熔融状态下将芳香族二
肼和两摩尔的苯基-
4-羟基苯酸酯反应而合成。这种合成路线提供了新的
化学结构高分子量POX,经济和合成上比其他路线更有利,并且由于有大量可用的活性芳香族二卤化物,因此可以轻松地进行
化学结构变化。