Method of producing polymorphic crystals of donepezil hydrochloride
The present invention provides a simple method of producing polymorphic crystal (III), which has high safety to environment and the bodies of operators; is gentle to environment; and can produce at low costs; and has a high refining effect. It is a method of producing polymorphic crystal (III) of donepezil hydrochloride (chemical name: 1-benzyl-4-[(5,6-dimethoxy-1-indanon)-2-yl]methylpiperidine•monohydrochloride) represented by the following structural formula (formula (I)), which comprises dissolving donepezil (chemical name: 1-benzyl-4-[(5,6-dimethoxy-1-indanon)-2-yl]methylpiperidine) in ethanol; and adding hydrochloric acid or hydrogen chloride thereto, followed by stirring.
1. 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 .
2. The method of producing polymorphic crystal (III) of donepezil hydrochloride according to claim 1 , wherein the amount of ethanol is 3 to 20 parts by weight to one part by weight of donepezil.
3. The method of producing polymorphic crystal (III) of donepezil hydrochloride according to claim 1 , which comprises, after adding hydrochloric acid or hydrogen chloride thereto, stirring while keeping the internal temperature at 10 to 40° C.
4. The method of producing polymorphic crystal (III) of donepezil hydrochloride according to claim 3 , which comprises, after adding hydrochloric acid or hydrogen chloride thereto, stirring while keeping the internal temperature at 10 to 40° C.; and, after one hour passes after crystals start precipitating, cooling to the internal temperature of 0° C. or more and less than 10° C.
5. The method of producing polymorphic crystal (III) of donepezil hydrochloride according to claim 1 , wherein after hydrochloric acid or hydrogen chloride is added thereto, seed crystals of polymorphic crystal (III) of donepezil hydrochloride is added thereto in an amount of 0.01 to 10% by weight to the weight of donepezil.