Patent ID: 7456296

Claim:
A process for preparation of crystalline perindopril erbumine of formula (II), exhibiting the following X-ray (powder) diffraction pattern, d-spacing Angle Relative Intensity (Å) (° 2θ) (%) 10.239 8.628 1.16 8.886 9.945 49.45 7.453 11.863 10.26 6.054 14.618 3.35 5.716 15.487 14.10 5.435 16.294 33.06 5.082 17.434 100.00 4.844 18.296 14.06 4.661 19.023 5.88 4.278 20.744 8.50 4.116 21.570 17.02 3.869 22.965 36.43 3.565 24.950 11.58 3.337 26.690 6.65 3.125 28.531 11.60 2.993 29.823 3.93 2.778 32.194 4.65 2.718 32.918 4.19 2.619 34.196 3.28 2.551 35.140 2.52 2.482 36.151 1.83 2.391 37.578 1.77 2.245 40.129 0.69 2.077 43.534 0.94 comprising, reaction of a solution of perindopril of formula (I), in a solvent selected from N,N-dimethylformamide, dimethoxymethane, 2,2-dimethoxypropane and 1,2-dimethoxyethane with tertiary butylamine and crystallization of the erbumine salt thus obtained by heating the reaction mixture to reflux, filtering hot, cooling to 20° C. to 30° C., and further cooling to 0° C. to 15° C. for 30 minutes to 1 hour and finally filtering off and drying the crystals.