Perfluoro-bis-1,3,4 oxadiazoles

Conclusions

• 1. The hydrazides of perfluorodicarboxylic acids of the general formula NH₂NHCO(CF₂)_nCONHNH₂ (n= 3,4,8,12) were produced by the action of hydrazine hydrate on the diethyl esters of the perfluorodicarboxylic acids in alcohol solutions.

• 2. Acylation of hydrazides of perfluorodicarboxylic acids by chlorides of carboxylic and perfluorocarboxylic acids produced N,N′-acyl derivatives of the hydrazides RCONHNHCO(CF₂)_nCONHNHCOR (n=3,4,8, R=C₃F₇. C₃H₇; n=3,12, R=C₆H₅).

• 3. Cyclodehydration of the N,N'-perfluoroacyl hydrazides of perfluorodicarboxylic acids with phosphoric anhydride at 300° yielded 2,2′-perfluoroalkyl-5,5′-polydifluoromethylene-bis-1,3,4-oxadiazoles.

• 4. 2,2′-Alkyl-5,5′-polydifluoromethylene-bis-1,3,4-oxadiazoles were produced by heating the N,N′-acyl hydrazides of perfluorodicarboxylic acids with POCl₃.