Abstract: A method for purifying (S)-oxiracetam is disclosed. Crude (S)-oxiracetam with the purity of 89% is dissolved in water; the solution is allowed to stand for 1 to 3 days at 0° C. to 18° C.; a colorless transparent crystal is precipitated; the solution is filtered and top-washed with cold water to 0° C. to 5° C.; and the product is dried in vacuum to obtain high-purity (S)-oxiracetam.

Abstract: A crystal form I of (S)-4-hydroxy-2-oxo-1-pyrrolidine acetamide, or named (S)-oxiracetam, is provided, which is characterized by a powder x-ray diffraction pattern that exhibits data of d-values versus the relative intensities as: 7.075(M), 5.355(S), 5.092(S), 4.590(M), 4.325(M), 4.259(S), 4.041(VS), 3.808(M), 3.542(M), 3.445(M), 3.393(M), 2.972(M), 2.914(S). A method for preparing a crystal form I of (S)-oxiracetam is also provided, which includes preparing the crude product and crystallizing A use of the crystal form I of (S)-oxiracetam in the manufacture of a medicament for preventing and treating memory dysfunction is also provided. Accordingly, the crystal form I of (S)-oxiracetam prepared by the method has high purity of more than 99.3% based on the percentages of the mass, with better efficacy than (S)-oxiracetam for preventing or treating memory dysfunction.

Abstract: A method for purifying levo-oxiracetam is disclosed. Crude levo-oxiracetam is dissolved in water; an organic solvent is added dropwise into the solution until the solution just turns turbid; the solution is allowed to stand for 1 to 3 days at 0° C. to 18° C.; a colorless transparent crystal is precipitated; the solution is filtered and top-washed with cold water of 0° C. to 5° C.; and the product is dried in vacuum to obtain high-purity levo-oxiracetam.

Abstract: A method for purifying (S)-oxiracetam is disclosed. Crude (S)-oxiracetam with the purity of 89% is dissolved in water; the solution is allowed to stand for 1 to 3 days at 0° C. to 18° C.; a colorless transparent crystal is precipitated; the solution is filtered and top-washed with cold water to 0° C. to 5° C.; and the product is dried in vacuum to obtain high-purity (S)-oxiracetam.

Abstract: A preparation method of (S)-4-hydroxy-2-oxo-1-pyrrolidine acetamide is provided, which includes the steps of preparing the crude product and crystallizing, wherein acetone and water are used as solvents in the step of crystallizing. The (S)-oxiracetam prepared by the method of the present invention has high purity of more than 99.3% and low impurity of 0-0.5%, based on the percentages of the mass. According to the method of the present invention, with regard to the way of charging materials, adding inorganic base only just a few times is easier to handle and more convenient to the industrial manufacturing and application.

Abstract: A crystal form I of (S)-4-hydroxy-2-oxo-1-pyrrolidine acetamide, or named (S)-oxiracetam, is provided, which is characterized by a powder x-ray diffraction pattern that exhibits data of d-values versus the relative intensities as: 7.075(M), 5.355(S), 5.092(S), 4.590(M), 4.325(M), 4.259(S), 4.041(VS), 3.808(M), 3.542(M), 3.445(M), 3.393(M), 2.972(M), 2.914(S). A method for preparing a crystal form I of (S)-oxiracetam is also provided, which includes preparing the crude product and crystallizing A use of the crystal form I of (S)-oxiracetam in the manufacture of a medicament for preventing and treating memory dysfunction is also provided. Accordingly, the crystal form I of (S)-oxiracetam prepared by the method has high purity of more than 99.3% based on the percentages of the mass, with better efficacy than (S)-oxiracetam for preventing or treating memory dysfunction.