Introduction
Here is described synthesis method of dl-Ephedrine from 1-Phenyl-1,2-propandion by means of catalytic reduction with hydrogen gas and Adams' catalyst. 1-Phenyl-1,2-propandion Can be purchased in international chemical market, other reagents are not so hard to buy. This is a one-pot reaction that uses gentle exposure to hydrogen gas. Pay attention to safety measures. Moreover, there are several simple methods of Ephedrine manufacturing such as Ephedrine extraction from plants, Synthesis of ephedrine from propiophenone, Methamphetamine from ephedrine tablets and Clean Green Ephedrine Manufacturing Process.
Equipment and glassware:
- 200 mL round bottom flask;
- Retort stand and clamp for securing apparatus;
- Hydrogen source;
- pH indicator paper;
- Vacuum source;
- Rotovap machine;
- Buchner flask and funnel [Schott filter may be used for small quantities];
- Glass rod and spatula;
- 100 mL x3; 50 mL x2 Beakers;
- Magnetic stirrer (optional);
- Silicone hose.
Reagents:
- Absolute ethyl alcohol ~150 mL;
- 1-Phenyl-1,2-propandion (0.05 mole) 7.4 g;
- Alcoholic solution of methylamine containing 1.6 g (0.05 mole);
- Platinum oxide (PtO2; Adams' catalyst) 0.1 g;
- Hydrogen chloride (HCl) alcoholic solution ~30 mL;
- Acetone ~200 mL.
Soluble in H2O 47.62 g/L (25 ºC), alcohol, ether, chloroform, and oils;
Melting point freebase: 37-39 ̊C;
Melting point HCI salt: 187-188 ̊C;
Molecular Weight: 165.236 g/mole;
Density: 1.124 g/cm3 (20 °C);
CAS Number: 299-42-3 (free base) and 50-98-6 (hydrochloride salt).
dl-Ephedrine hydrochloride synthesis procedure
A mixture of 50 mL of absolute ethyl alcohol, 7.4 g of 1-Phenyl-1,2-propandion (0.05 mole) and an alcoholic solution of methylamine containing 1.6 g (0.05 mole) was reduced catalytically with hydrogen in the presence of 0.1 g of platinum oxide (PtO2) in 200 mL round bottom flask. In some experiments, there was a long induction period and then the yield was low. This behavior could be obviated by reducing the catalyst first and then adding the reactants. When reduction no longer proceeded, the catalyst was removed by filtration and about half the alcohol removed under reduced pressure. By this means, any excess of methylamine was removed. The solution was made just acid with alcoholic hydrogen chloride up to pH 6.5-7 and evaporated to dryness. The solid hydrochloride was washed with cold acetone and dried. A small amount of pseudoephedrine hydrochloride could be extracted from this by means of hot chloroform and by working up a number of extractions sufficient was obtained for definite identification (m.p. 164 °C; free base, m.p. 118 °C).
The dl-Ephedrine hydrochloride was purified by recrystallizing once from alcohol-acetone and melted at 189 °C. The free base was recrystallized from chloroform-petroleum ether. The yield was 2.5-4.0 g (25-40 %).
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