Sulfuric Acid → 3-Methoxy-1,2-thiazole-4-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 7.9 g. (0.05 mole) of 4-carbamoyl-3-methoxyisothiazole prepared as in Example 19 in 90 ml. of 80% sulfuric acid at 10°-15° C. was added slowly beneath the surface of the liquid a solution of 9.5 g. (0.137 mole) of sodium nitrite in 13 ml. of H2O. When addition was complete the solution was allowed to come to 25° C., and then was heated to 60° C. for several minutes. After cooling to 25° C. the reaction solution was poured onto ice to precipitate 3.64 g. (46%) of 4-carboxy-3-methoxyisothiazole as a white solid, m.p. 182°-185° C.

Provenance & Evidence