Abstract: A preparing method for high-purity levetiracetam, comprising: adjusting the pH of an extracted aqueous layer obtained by dissociating (S)-?-ethyl-2-oxo-1-pyrrolidineacetic acid (R)-methylbenzylamine salt to 5-9; removing water; adding an organic solvent to form a solution and then performing an esterification reaction with ethyl chloroformate or methylchlorofonmate; and carrying out an ammonolysis reaction to obtain the levetiracetam. The method simplifies production process, increases yield, reduces or even avoids the use of triethylamine in the esterification process, and reduces the emission of a great amount of three wastes.

Abstract: Provided is a method for preparing a pregabalin intermediate 3-isobutylglutaric acid monoamide. The method comprises: 1) adding 3-isobutylglutaric acid and urea into a first organic solvent; 2) keeping warm and refluxing when heated to 100-140° C.; 3) adding water when cooled to 70-90° C.; 4) adding an ion membrane alkaline when cooled to 40-60° C., adjusting the pH to 11.0-14.0, then keeping warm at 40-60° C.; 5) when finished keeping warm, removing an organic layer; 6) adding an acid into the water layer to adjust the pH to 1.0-3.0; 7) extracting the solution acquired in step 6) by using a second organic solvent of a total volume of V, vacuum distilling 0.5-0.6 V of the organic solvent from an organic layer acquired by extraction; and 8) cooling to 0-15° C. and crystallizing to acquire 3-isobutylglutaric acid monoamide.

Abstract: Provided is a purifying method for dabigatran etexilate free base, comprising subjecting a dabigatran etexilate free base crude product to water slurrying to obtain a crude product B; then conducting recrystallization on the crude product B with acetone and water to obtain a crude product C; and subsequently, purifying the crude product C with a mixed solvent of tetrahydrofuran and ethyl acetate, filtering and drying to obtain a dabigatran etexilate free base finished product. The purifying method of the present invention can effectively remove various impurities and is suitable for workshop production. Salts and water-soluble organic impurities are removed by purified water slurrying, impurities with a high polarity are removed by purifying with an acetone-water solution, and impurities with a low polarity are removed by purifying with a mixed solvent of tetrahydrofuran and ethyl acetate.

Abstract: Provided is a method for preparing a pregabalin intermediate 3-isobutylglutaric acid monoamide. The method comprises: 1) adding 3-isobutylglutaric acid and urea into a first organic solvent; 2) keeping warm and refluxing when heated to 100-140° C.; 3) adding water when cooled to 70-90° C.; 4) adding an ion membrane alkaline when cooled to 40-60° C., adjusting the pH to 11.0-14.0, then keeping warm at 40-60° C.; 5) when finished keeping warm, removing an organic layer; 6) adding an acid into the water layer to adjust the pH to 1.0-3.0; 7) extracting the solution acquired in step 6) by using a second organic solvent of a total volume of V, vacuum distilling 0.5-0.6 V of the organic solvent from an organic layer acquired by extraction; and 8) cooling to 0-15° C. and crystallizing to acquire 3-isobutylglutaric acid monoamide.