NEW MATERIAL:2-[4(p-Fluorobenzoyl)-piperidin-1-yl]-2'-acetonaphthone hydrochloride crystals having specific diffraction angles (2θ) in the powder X-ray diffractometry. The diffraction angles are 12.6±0.1; 16.0±0.1; 17.0±0.1; 17.1±0.1; 17.7±0.1; 19.0±0.1; 21.0±0.5; 20.0±0.1; 25.8±0.1.

USE: It has actions to improve the metabolism in the cerebral circulation, develop therapeutic effect on memory defects and inhibit glutamate liberation.

PREPARATION: 2-[4-(p-fluorobenzoyl)-piperidine-1-yl]-2'-acetonaphthone hydrochloride (abbreviated to compound A) is dissolved in methanol or a methanol and chloroform mixed solvent with heat, then rapidly cooled down, or combined with ether under stirring to effect rapid precipitation to give crystals of compound A. The crystals are chemically stable and has a dissolution rate about double that of conventional crystals.