Patent ID: 7479563

Claim:
A method of producing a crystalline form (III) of donepezil hydrochloride (chemical name: 1-benzyl-4-[(5,6-dimethoxy-1-indanon)-2-yl]methylpiperidine•monohydrochioride) represented by the following structural formula 1: by the steps of: dissolving donepezil (chemical name: 1-benzyl-4-[(5,6-dimethoxy-1-indanon)-2-yl]methylpiperidine) in ethanol; adding hydrochloric acid or hydrogen chloride thereto; stirring while keeping the internal temperature at 10 to 40° C.; and then collecting by filtration and drying the resulting crystals; wherein the crystalline form (III) of donepezil hydrochloride is a crystalline form having peaks at the following diffraction angles (2θ) in its powder X-ray diffraction patterns; TABLE 1 Diffraction angle (2θ°) Intensity (I/Io) 6.56 30 9.94 8 13.00 17 15.00 47 15.26 14 15.74 6 16.48 35 17.42 4 18.10 21 18.50 56 19.50 17 20.10 32 20.94 21 21.66 100 22.32 25 22.92 17 23.92 19 24.68 17 26.00 44 27.20 23 28.02 29 28.22 40 28.60 13 with absorption at the following wave numbers in its infrared absorption spectrum in potassium bromide: 559, 641, 648, 702, 749, 765, 786, 807, 851, 872, 927, 949, 966, 975, 982, 1007, 1034, 1071, 1080, 1111, 1119, 1131, 1177, 1190, 1205, 1217, 1230, 1250, 1265, 1292, 1313, 1367, 1389, 1420, 1438, 1453, 1461, 1470, 1500, 1589, 1605, 1697, 2407,2419, 2461, 2624, 2641, 2651, 2667, 2837, 2848, 2873, 2924, 2954, 2961, 2993, 3007, 3377, 3433 cm −1 ; or a crystalline form having peaks at the following diffraction angles (2θ) in its powder X-ray diffraction patterns; TABLE 2 Diffraction angle (2θ°) Intensity (I/Io) 6.48 21 9.84 7 12.96 19 14.94 45 15.20 13 16.44 31 18.04 20 18.46 55 19.44 17 20.02 30 20.86 20 21.02 13 21.58 100 22.22 23 22.90 15 23.92 13 24.64 15 25.92 40 26.18 17 27.14 21 28.14 37 28.56 11 29.94 12 with absorption at the following wave numbers in its infrared absorption spectrum in potassium bromide: 558.3, 641.1, 702.4, 748.5, 765.0, 786.1, 807.3, 850.8, 872.0, 926.8, 974.9, 1034.1, 1071.5, 1111.6, 1190.1, 1216.6, 1265.4, 1291.9, 1312.9, 1364.4, 1420.2, 1438.1, 1458.8, 1499.1, 1522.2, 1542.6, 1560.1, 1570.2, 1589.1, 1638.8, 1647.8, 1654.3, 1697.3, 1718.1, 1734.5, 1751.4, 1773.7, 1793.5, 1845.8, 2345.3, 2461.6, 2924.2, 3447.9 cm −1 .