Formoterol tartrate process and polymorph
A method of preparation of a highly pure salt of R,R-formoterol L-tartrate is disclosed. The process provides the most thermodynamically stable polymorph by recrystallization of a novel polymorph.
1. (R,R)-formoterol L-tartrate in the form of a crystalline solid consisting of greater than 99.6% by weight of formoterol L-tartrate at least 95% in the polymorphic form of a thermodynamically stable third polymorph (A) of (R,R)-formoterol L-tartrate, said polymorph (A) having peaks at the diffraction degrees with the intensity shown below in an X-ray powder diffraction pattern:
peak number
2-Theta
Intensity
1
8.8
33.1
2
9.3
33.4
3
12.1
58.1
4
12.4
60.6
5
14.2
30.9
6
15.2
87.4
7
15.5
82.8
8
16.8
69.8
9
18.9
39.6
10
19.7
41.1
11
20.8
40.6
12
22.5
38.8
13
23.0
59.9
14
23.7
100.0
15
25.6
55.9
16
26.8
37.2
17
28.6
25.6
18
30.9
37.2
19
36.1
28.0
20
38.1
25.0
21
39.1
22.7
22
41.5
21.3
23
43.3
20.9