PROCESS FOR PREPARING SUBSTITUTED OXADIAZOLONES

摘要

Substituted oxadiazolones of the formula (I), (see fig. I) in which R represents optionally substituted alkyl ¢which are known as intermediates for the preparation of certain herbicides! are obtained in good yields and high purity when in a first step carboxylic acids of the general formula (II) R-COOH (II) are reacted with hydrazine hydrate in the presence of a catalyst and, if appropr iate, in the presence of an inert diluent at temperatures between 0.degree.C and 150.degr ee.C with elimination of water, and the resulting carboxylic hydrazides of the general for mula (III) R-CO-NH-NH2 (III) are reacted in a second step in the same reaction medium - i.e. without isolatio n of the intermediate - with phosgene (COCl2) at temperatures between 20.degree.C and 120.degree.C.