Process for the preparation of 1,2,3-thiadiazol-5-yl ureas

A process for the preparation of 1,2,3-thiadiazol-5-yl ureas of the formula ##STR11## where R.sub.1 is hydrogen or C.sub.1 -C.sub.4 -alkyl;

• R.sub.2 is C.sub.1 -C.sub.4 -alkyl, C.sub.5 -C.sub.8 -cycloalkyl, C.sub.5 -C.sub.8 -cycloalkyl substituted by one or more alkyl groups, pyridyl, pyrimidyl, phenyl, or phenyl substituted by one or more residues selected from the group consisting of alkyl, halogen, alkylthio, alkoxy, trifluoromethyl and nitro, or in which R.sub.1 and R.sub.2 with the N-atom form a morpholino-, piperidino- or pyrrolidino-group, comprising
• reacting a compound of the formula ##STR12## with an acid halide of the formula
• R.sub.4 --X III
• dissolved in an inert organic solvent in the presence of acid binding agents to form acylated 1,2,3-thiadiazol-5-carbohydroxam acid derivatives of the formula ##STR13## reacting this compound with an amine of the general formula ##STR14## and isolating the product, in which R.sub.1 and R.sub.2 are as defined above, R.sub.3 is hydrogen or a univalent metal atom, R.sub.4 is C.sub.1 -C.sub.4 -alkylcarbonyl, C.sub.1 -C.sub.4 -alkylcarbonyl substituted by one or more halogen atoms, C.sub.1 -C.sub.4 -alkoxycarbonyl, benzoyl, benzoyl substituted by halogen, methyl or methoxy, phenyl sulfonyl, phenylsulfonyl substituted by halogen, methyl or nitro, alkylsulfonyl or alkylsulfonyl substituted by alkyl or benzyl, and X is a halogen atom.