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In a solution of 18.7 g. of sodium hydroxide in 400 ml. of water was suspended 104 g. of methyl 6-chloro-5-ethylamino-3-methoxypyrazine-2-carboxylate and the suspension was stirred for 15 hours at room temperature to give a homogeneous solution. The solution was acidified with 80 ml. of an aqueous 18% hydrochloric acid solution and then allowed to stand for 2 hours at 5°-10° C. The crystals formed were recovered by filtration, washed with water and dried over anhydrous phosphorous pentoxide under reduced pressure to provide 92.5 of 6-chloro-5-ethylamino-3-methoxypyrazine-2-carboxylic acid. Melting point 166.5°-166° C. (recrystallized from chloroform).

1. customto give a homogeneous solution
2. customThe crystals formed
3. filtrationwere recovered by filtration
4. washwashed with water
5. dry with materialdried over anhydrous phosphorous pentoxide under reduced pressure