NEW MATERIAL:An oxadiazolinone derivative of formulaI(X is H, halogen, lower alkyl, lower alkoxyl or trifluoromethyl group).

EXAMPLE: 5-Chloro-3-(2-methoxyphenyl)-1,3,4-oxiadiazolin-2-one.

USE: An insecticide.

PROCESS: An oxadiazolinone derivative of formula II is reacted with one equivalent or more phosphorus pentachloride preferably in a suitable solvent, e.g. phosphorus oxychloride, benzene or toluene, at 0W250°C to give the titled compound. After the completion of the reaction, the solvent is removed, and the resultant compound of formulaIis if necessary purified by a means, e.g. the chromatography, distillation or recrystallization.