mixture under reduced pressure and co-distilled with n-heptane. The obtained compound was kept a side for 3 days at 25-30°C, collected the solidified compound and dried to get the title compound. Yield: 4 gm; PXRD of the obtained compound is shown in figure-11. Example-8: Preparation of Tapentadol tartrate
Step-a: Aqueous hydrogen bromide (200 ml) was added to (2R, 37?)-3-(3-methoxyphenyl)-
AW,2-tri methylpentan-1-amine hydrochloride (100 gm) at 25-30°C. Heated the reaction
mixture to 115-120°C and stirred for 1 '/2 hour at the same temperature. Cooled the reaction
mixture to 40-45°C and water was added to it. Further cooled the reaction mixture to 0-5°C.
Basified the reaction mixture using aqueous ammonia at the same temperature. Ethyl acetate
was added to the reaction mixture at the same temperature and raised the temperature of the
reaction mixture to 25-30°C. Stirred the reaction mixture for 10 minutes and separated both
the organic and aqueous layers. The aqueous layer was extracted with ethyl acetate.
Combined the organic layers and washed with water. The organic was dried over sodium
sulfate. Distilled off the solvent completely from the filtrate under reduced pressure. Methyl
tertiarybutyl ether (390 ml) was added to the obtained compound at 25-30°C and stirred for
10 minutes. Filtered the reaction mixture and washed with methyl tertiarybutyl ether.
Step-b: L(+)-tartaric acid (52.87 gm) was dissolved in 390 ml of isopropyl alcohol at 43-
48°C, filtered the obtained solution and washed with isopropyl alcohol. Heated the obtained ■
filtrate to 43-48°C and slowly added filtrate obtained in step-a) at the same temperature
stirred the reaction mixture for 15 minutes at the same temperature. The reaction mixture was
seeded with crystalline Tapentadol tartrate at 40-43°C. Cooled the reaction mixture to 25-
30°C and stirred for 45 minutes at the same temperature. Further cooled the reaction mixture
to -10 to -5°C and stirred it for 2 hours at the same temperature. Filtered the precipitated
solid, washed with the mixture of isopropanol & methyl tertiarybutyl ether and dried to get
the title compound. Yield: 105 gm.