Abstract: The present invention provides an (R)-4-hydroxy-2-oxo-1-pyrrolidineacetamide crystal form, which has diffraction peaks when 2? is 12.423±0.2°, 16.465±0.2°, 17.344±0.2°, 21.889±0.2°, and 25.054±0.2°. The present invention can promote synthesis of phosphorylcholine and phosphoethanolamine and promote cerebral metabolism, has a stimulating effect on the specific central nervous pathway through the blood-brain barrier, and has special biological activity in the fields of sedation, anti-epilepsy, etc. The (R)-4-hydroxy-2-oxo-1-pyrrolidineacetamide crystal form in the present invention has a melting point peak temperature of 133.1±2° C. and a solubility in water of greater than or equal to 100 mg/mL, dissolves fast in water, provides high bioavailability, good stability, and good particle fluidity, is suitable for production of pharmaceutical preparations and storage and transportation.

Abstract: The present invention provides a crystalline form of dextral oxiracetam. The crystalline form has a diffraction peak when a diffraction angle, 2?, is 17.76±0.2°, 20.16±0.2°, 21.20±0.2°, 24.17±0.2°, or 25.88±0.2°. The crystalline form of dextral oxiracetam can promote synthesis of phosphorylcholine and phosphoethanolamine, boosts cerebral metabolism, has a stimulating function on a specific central nervous pathway through a blood-brain barrier, and has special biological activity in the field of sedation and the antiepileptic field. The crystalline form of dextral oxiracetam of the present invention is a water-containing crystalline form, contains 0.5 water molecules, loses crystallization water at 73.5±2° C., and is melted and decomposed at 138.0±2° C.

Abstract: A crystalline form of (R)-4-hydroxy-2-oxo-1-pyrrolidineacetamide is disclosed. The crystalline form has a diffraction peak when a diffraction angle, 2?, is 16.66±0.2°, 17.54±0.20, 21±0.2°, 22.16±0.20, or 30.96±0.20. The crystalline form can be dissolved quickly in water with a solubility greater than or equal to 90 mg/mL, features high bioavailability, has high stability at high temperature, is suitable for preparing multiple pharmaceutical compositions, and can prepare multiple formulations, such as tablets, capsules, dripping pills, sustained-release and controlled-release formulations, and lyophilized powder for injection. The method for preparing the crystalline form is carried out under a mild condition, is easy to operate, introduces a few impurities, and features good reproducibility, an easy-to-control production process and high safety, and is suitable for industrial production.

Abstract: (S)-4-hydroxy-2-oxo-1-pyrrolidine crystal form III (called crystal form III of (S) -oxiracetam for short) has diffraction peaks at diffraction angles 2?, wherein the diffraction angles 2? are equal to 10.54, 13.70, 14.44, 15.60, 17.12, 18.88, 19.24, 20.66, 20.84, 21.18, 21.82, 22.94, 23.24, 24.88, 27.20, 27.48, 28.24, 30.46, 30.80, 31.52, 32.00, 32.34, 32.90, 33.20, 34.40, 34.62, 37.30, 37.50, 38.28, 38.96, and 40.02°. The (S)-oxiracetam crystal form III of the present invention has an obvious effect on memory dysfunction, is dissolved in water fast, has high bioavailability, and can be used to prepare various pharmaceutical compositions. The (S)-oxiracetam crystal form III obtained by using the preparation method of the present invention is high in purity. The preparation method of the present invention is performed in a mild condition, is easy in operation, introduces less impurities, has desirable reproducibility, is easily controlled during production, and is applicable to industrial production.