Here is the relevant experimental section of J. Pharm. Pharmac., 1978, 30, 15-19
2-Methylamino-1-phenyl-propanone(III)
(-)Ephedrine (1.0 g, 6.1 mmol) was refluxed in benzene (50 ml) with 'active silver carbonate' on Celite (10.1 g = to 18 m mol Ag2CO3) . . . in a Dean Stark apparatus until no more water was collected (60 min). The Celite/silver carbonate residues were filtered and washed, and the combined organic layers extracted with 2 M hydrochloric acid (2 * 20 ml). The acid layers were basified and extracted with ether (3 * 20 ml), the ether extracts dried (anhydrous MgSO4) and the basic components precipitated with HCl gas (0.46 g yield). The salt was recrystallized from ethanol-ether to give the title compound as an off-white solid (0.33 g, 33% yield), m.p. 170-178 deg C (with decomp.) (cf. Takamatsu, 1956, 173-175)
Oxidation of (-)ephedrine base with nickel peroxide
(-)Ephedrine base (0.03 g) was shaken for 15 min with nickel peroxide (0.01 g), in ether. The products were qualitatively examined by g.l.c. The product of oxidation of ephedrine base with nickel peroxide, gave peaks due to benzaldehyde (Rt 1.4 min) and the oxazolidones IIbi (Rt 7.6 min) and IIbii (a diastereoisomer of IIbi, Rt 9.9 min, 10% peak height of IIbi) on g.l.c. system 1.
Oxidation of (-)ephedrine base with 'active silver carbonate'
The product of oxidation of ephedrine with 'active silver carbonate' gave two peaks on g.l.c. (system 1 or 2); a sharp peak at 12.7 min, merging into a much broader peak centered at ca 15 min, which tailed extensively away from the solvent front towards the ephedrine peak. A small quantity of benzaldehyde and a negligible quantity of IIbi were also formed. A g.l.c.-ms run of the 12.7 min peak showed the base ion at m/e 58 with an m/e 56 ion increasing rapidly in intensity as subsequent scans were made, the m/e 58 ion rapidly decreasing in intensity. The main product isolated from the reaction was 2-methylamino-1-phenyl-1-propanone (III). See also the g.l.c. properties of III below, and under the synthesis.
Oxidation of (-)ephedrine base with 'active manganese dioxide'
(-)Ephedrine base (10.0 g, 61 mmol) was stirred in ether (100 ml) with 'active manganese dioxide' (65 g; prepared by Attenburrow, Cameron & others, 1952) at room temperature for 1 h. The manganese dioxide was removed by filtration, washed with ether and the residue discarded. The combined ethereal filtrates were examined qualitatively by g.l.c. and g.l.c.-ms.
A mixture of products similar to those from both the above oxidations was obtained.
So I have a question for anybee that can answer it: Can the yield of the above manganese dioxide oxidation of (-)ephedrine be determined through a qualitative g.l.c. and g.l.c.-ms scan of the ethereal filtrates?
Here's some more useful information taken from A.J. Fatiadi, Synthesis, 65 (1976):
. . . Another proceedure (ref 36) for active manganese dioxide involves the oxidation of acetone with potassium permanganate via internal cleaving of water. A filtered, saturated solution of potassium permanganate in acetone is kept at room temperature for 48-72 h. The resulting fine, somewhat bluish powder (<0.2mm) is filtered off, washed with aqueous acetone, and activated at 110-120 deg C for 16 h. Alternatively, finely ground potassium permanganate is refluxed with an excess of acetone until the pink color is discharged (3 to 4 h). The precipitate is filtered off, washed and dried at 110-120 deg C, or activated by azeotropic distillation of benzene (ref 37). . . .
Ref 36: A.J. Fatiadi, unpublished results.
Ref 37: I.M. Goldman, J. Org. Chem. 34, 1979 (1969).
