Large scale preparation of 3-Methyl-4H-[ 1, 2, 4]oxadiazol-5-one
Process Development for the potassium and sodium salts of 3-Methyl-4H-[ 1, 2, 4]oxadiazol-5-one 1A and 1B.
The development of a safe and practical process for the potassium and sodium salts of 3-Methyl-4H-[ 1, 2, 4]oxadiazol-5-one 1A and 1B is described. The focus of the report is how the scale-up issues of the original procedure are overcome, in particular, the thermal hazards of the starting material, hydroxylamine, and the intermediate, acetamidoxime. The final process was demonstrated multiple times on a 600-L scale with consistent yields (70%) and purities (95%).