Novel pyrazolidine derivative and its preparation

摘要

The invention relates to a process for the preparation of 1,2-diphenyl-3,5-dioxo-4-n-butylpyrazolidine sodium monohydrate. According to the invention, the phenylbutazone (1,2-diphenyl-3,5-dioxo-4-n-butylpyrazolidine) is reacted with sodium carbonate or sodium hydrogen carbonate at 60-85@C in an aliphatic alcohol having 1-5 carbon atoms or in a mixture of an aromatic solvent and water, the organic solvents in the final reaction phase are removed, and the water content is brought to a value of 0.9-5.0 % by weight while the product is isolated from the resulting suspension at 15 +/- 5@C.