Hydrochloric Acid → 2-(5-Amino-1,2,4-thiadiazol-3-yl)-2-methoxyiminoacetic acid

Participants

Reaction Conditions

Reaction Steps

To a suspension of methyl 2-methoxyimino-2-(5-formamido-1,2,4-thiadiazole-3-yl)-acetate (syn-isomer) (146 g, 0.60 mmol) in water (720 g) was cooled to an internal temperature of 0° C. and then 10% aqueous sodium hydroxide solution (720 ml) was added dropwise thereto. The mixture was allowed to react at a temperature in the range of 0°±1° C. for 1 hr., then heated to an internal temperature of 45° to 50° C. to react for 2 hrs. The reaction mixture was then neutralized with concentrated hydrochloric acid (62.4 g) to pH 6.5 to 7.5., and concentrated at an internal temperature of below 60° C. and then adjusted to pH 3 with concentrated hydrochloric acid (62 g). After that, it was decolorized and purified with activated carbon (14.6 g), followed by the addition of concentrated hydrochloric acid (62.4 g). It was then cooled to separate crystals which were collected by filtration and dried to give 2-methoxyimino-2-(5-amino-1,2,4-thiadiazole-3-yl) acetic acid (syn-isomer) (166.7 g, yield: 88.0%, and purity by HPLC: 99.4%).

Provenance & Evidence