I don`t take it as questioning
. We are here to help each other with information. As I haven`t tried this conversion (neither from racemic nor from D-amphetamine) I can only rely on Rhodium`s notes on
I would just use racemic amphetamine by the way, as Methamphetamine can be resolved by the same methods as amphetamine and why risk valuable D isomer when the end results are not known.
`Formaldehyde and Aluminum Amalgam`
N-Methyl-amphetamines were prepared by the reaction of the corresponding amphetamine with formaldehyde and reduction in the absence of acid. Thus, a mixture of 1 mole amphetamine freebase (136g) and 1 mole aqueous formaldehyde (81ml 37% or 75ml 40%) in 350 ml alcohol and an excess of aluminum amalgam was reduced for several hours, water added, aluminum hydroxide filtered off, the solution acidified and evaporated, and the freebase separated by means of alkali yielding phenyl-N-methylisopropylamine, converted to the hydrochloride, mp 140°C.
Similarly, 70g d-amphetamine in alcohol with aluminum and 1 mole formaldehyde gave d-methamphetamine, which was converted to the phosphate salt. 1-Phenyl-2-aminopropanol similarly yielded ephedrine.`
(Emphasis from me.)
Anyway, I still invite anyone out anyone to share his experience having actually tried this synthesis and having some real-life experience with it. I am going to try it at some point, but would have been great to know that it really works before sacrifising a lot of material and time. The other option is starting from P2NP reducing it to the imine and then hydrolysing in acidic environment to P2P, but this then involves a further amination of the P2P with methylamine which I think is excessive as there has already been one (following condensation of benzaldehyde with nitroethane). The method I would use also requires quite a lot of Acetic acid to reduce e.g. on iron catalyst then hydrolyse with the acid. If there is no one having tried this, then I will do a comparison and let the forum members know.