Exchange amination process for preparing 2-hydrazinobenzothiazoles

Process for the preparation of a compound of the formula ##SPC9##

• wherein each R.sup.1 independently represents hydrogen, halo, lower alkyl of C.sub.1 -C.sub.3, lower alkoxy of C.sub.1 -C.sub.3, or lower alkylthio of C.sub.1 -C.sub.3, subject to the limitation that at least two R.sup.1 's represent hydrogen;
• which process comprises reacting a corresponding 2-aminobenzothiazole compound of the formula ##SPC10##
• wherein each R.sup.2 independently represents hydrogen or methyl with hydrazine under the following conditions:
• 1. in the presence of an acid exhibiting a pK.sub.a of 5 or less, in the ratio of 0.1 to 1.0 molecular proportion of said acid for each molecular proportion of hydrazine;
• 2. at a temperature above 100.degree.C.;
• and
• 3. in a solvent selected from the group consisting of C.sub.2 -C.sub.4 -alkylenediols;
• di- and tri(ethylene and propylene) glycols;
• mono(C.sub.1 -C.sub.4 -alkyl) ethers of ethylene and propylene glycols;
• mono(C.sub.1 -C.sub.4 -alkyl) ethers of di- and tri(ethylene and propylene) glycols;
• triethanolamine;
• sulfolane;
• and dimethylsulfoxide.