Ephedrine hydrochloride synthesis
- Product Name:Ephedrine hydrochloride
- CAS Number:50-98-6
- Molecular formula:C10H15NO.ClH
- Molecular Weight:201.69
Yield:50-98-6 74%
Reaction Conditions:
Stage #1:(R)-1-hydroxy-1-phenyl-2-propanone;methylamine with 5%-palladium/activated carbon;hydrogen in water;toluene at 30 - 55; under 1500.15 - 3000.3 Torr;
Stage #2: with hydrogenchloride in water;toluene; pH=2
Steps:
1 Preparation of (1/f ,25)-l-ephedrine HC1
To the 600 mL of concentrated mass of toluene containing (R)-phenylacetylcarbinol I, 40percent solution of aqueous monomethylamine 62 g was added. The resulting mass was hydrogenated at 30 °C to 55 °C at 2 kg/cm2 to 4 kg/cm2 of hydrogen pressure in the presence of 5percent platinum on carbon (8 g) till hydrogen consumption ceases. The mass was maintained at 40 °C to 55 °C in 2 kg/cm2 to 4 kg/cm2 of hydrogen gas pressure. The progress of the reaction mass was monitored by GC and mass was cooled to 30 °C to 35 °C. The platinum catalyst was filtered off and to the filtrate water of 150 mL was added. The pH of the reaction mass was adjusted to about 2.0 with hydrochloric acid and the aqueous layer was separated. The separated aqueous layer was concentrated under reduced pressure and the precipitated product was isolated using acetone 160 mL at 20 °C to 25 °C. The isolated ephedrine hydrochloride was washed with acetone 100 mL to yield crude ephedrine hydrochloride. The crude ephedrine hydrochloride on re-crystallisation with water yields (80 g, 74 percent), (1R,2S)-Ephedrine hydrochloride as white crystalline solid. Purity by HPLC > 99.5 percent with 99.5 percent ee, Specific optical rotation: (-) 32.4 °.
References:
MALLADI DRUGS AND PHARMACEUTICALS LTD.;V.N., Gopalkrishnan;S., Shreya;R., Saravanan;S., Perumal;K., Balamurugan WO2020/129087, 2020, A1 Location in patent:Page/Page column 12
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