So here's my rationale for MDP2Pol and/or N,N-dimethyl-MDA (MDDM) appearing as synthetic impurities in MDMA synthesized by reductive amination of
MDP2P with MeNO2 under acidic conditions:
- direct reduction of the ketone leads to MDP2Pol, this should be unlikely but may occur with excessively high temps / too much reducing agent
- the Nef reaction on MeNO2 generates formaldehyde, which may reductively aminate MDMA to MDDM.
But neither possibility acceptably explains the 3.5-3.7 peak.
There is another peak that changes in the good sample relative to the "meh" samples, around 2.7. The "meh" samples have peaks around
2.55-2.59 but the good one is at 2.71. This shift is small but it could be meaningful. Published NMR spectra of MDMA tell me that this peak is
typically located on the N-methyl group and furthermore that it should be at 2.7, which does suggest that we're getting somewhere.
In fact, since the NH proton apparently does not appear in the NMR spectrum (can someone confirm?), I think this shift could be consistent with double
N-methylation leading to MDDM impurities.
Reference NMR attached. |