Ephedrone [α-
Methylaminoethyl Phenyl Ketone (
IV)]
A flask fitted with a stirrer, a dropping funnel, a thermometer, and an air inlet tube contained 56.5 g (0.421 mole) of propiophenone and 130 ml of benzene; 67.5 g (0.421 mole) of bromine was added to the mixture at 30?C at such a rate that the bromine became decolorized. If the decolorization of the reaction mixture was slow, air was blown through it to remove the hydrogen bromide formed. After the bromine had been added the solution was stirred for 30 minutes and hydrogen bromide was then blown out of the solution with the stirrer running. After removal of hydrogen bromide 30 ml of water was added to the solution, the mixture was stirred thoroughly, and 20% sodium carbonate solution was added until the mixture was weakly alkaline to litmus. A solution of 56.5 g (0.835 mole) of methylamine hydrochloride in 55 ml of water was then added. A solution of 67.5 g (1.67 moles) of caustic soda in 80 ml of water was added during 10 minutes at 50-60?C; the temperature was raised to 70?C. At the end of the reaction the mixture was cooled to room temperature; unconverted methylamine was blown out by air into absorption flasks containing 5% hydrochloric acid. The benzene and aqueous alkaline layers were then separated, the latter was extracted twice with benzene, and the extracts were added to the main solution. This solution was washed with water and stirred with 1 N hydrochloric acid solution. The resultant aqueous solution of ephedrone hydrochloride was evaporated under vacuum to a thick syrup; this was stirred with acetone to yield a white precipitate of ephedrone hydrochloride. The precipitate was heated to boiling with acetone and cooled; the white crystals were filtered off, washed with acetone, and dried.
A certain amount of less pure ephedrone hydrochloride was additionally obtained from the mother liquors and crystallized from a mixture of ethyl alcohol and acetone. The total amount of ephedrone hydrochloride, mp 175-179?C, was 59-62 g (70-74% on the propiophenone taken).
The solution of methylamine hydrochloride collected in the absorption flask was evaporated to dryness; 21 g of methylamine hydrochloride was recovered, mp 220-222?C (literature value, 225-226?C
10).
DL -Ephedrine Hydrochloride (
V)
A solution of 14.2 g of caustic soda in 135 ml of ethyl alcohol was added to a solution of 62 g of ephedrone hydrochloride to give an alkaline reaction to phenolphthalein; the precipitated sodium chloride was filtered off and washed with alcohol; the washings were added to the main alcoholic solution of ephedrine base. This solution was reduced by molecular hydrogen in presence of Raney nickel catalyst at room temperature and atmospheric pressure. At the end of the reduction the solution was cooled to 5-10?C the catalyst was filtered off, and the solution was acidified with a solution of hydrogen chloride in alcohol; the precipitate sodium chloride was filtered off and the filtrate was evaporated under vacuum at a temperature not higher than 45?C The yield was 40 g of DL-ephedrine hydrochloride, mp 184-187?C After crystallization from ethyl alcohol the crystals had mp 187-190?C (literature value 187?C
5).
After treatment of the mother liquors the total yield of DL-ephedrine hydrochloride was 64% on the ephedrone taken. In addition, 19% of pseudoephedrine was obtained.