Structural Determination of the Principal Byproduct of the Lithium-Ammonia Reduction Method of Methamphetamine Manufacture

Abstract

One common method of illicit methamphetamine manufacture utilizes an alkali metal, typically lithium, and liquid ammonia to chemically reduce ephedrine or pseudoephedrine to form methamphetamine. This method is often referred to as the lithium-ammonia reduction method or the Birch reduction method. While the hydroxyl group of ephedrine is more reactive than the aromatic ring, excess alkali metal and the presence of a proton source allow the formation of a cyclohexadiene byproduct not found in samples of methamphetamine produced from other manufacturing methods. A sample enriched in this byproduct was generated and characterized using nuclear magnetic resonance (NMR) spectroscopy, gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectrophotometry, and ultraviolet (UV) spectrophotometry. The chemical structure of this byproduct was determined to be 1-(1 ,4-cyclohexadienyl)-2-methylaminopropane (CMP).

A study of the use of Ephedra in the manufacture of methamphetamine

“…The mass spectra of CMP, observed in both reduction reactions, was consistent with the literature (Fig. 6) [12,18].…”

“…The following reductions were carried out using variations of previously reported methods: red phosphorus and iodine reduction [6,7,8], hypophosphorous acid and iodine reduction [10], dissolving metal reduction [11][12][13] and metal catalysed reduction [14,15]. Specific details of the reduction reactions and analytical data are available from the author.…”

“…More recently, the utility of lithium/ammonia in the selective reduction of benzyl alcohols has been recognised [17]. This has subsequently led to the technique being used extensively in the clandestine manufacture of methamphetamine [11][12][13].…”

“…A limitation of this reaction is the over-reduction of the amphetamine product when an excess of the alkali metal is present in the reaction mixture. For example samples of methamphetamine produced in a clandestine environment often contain a byproduct, which has recently been identified as 1-(1 0 ,4 0 -cyclohexadienyl)-2-methylaminopropane (CMP) [12,18].…”

Degradation in soil of precursors and by-products associated with the illicit manufacture of methylamphetamine: Implications for clandestine drug laboratory investigation

“…As a result of over-reduction of the precursor, a key by-product in DMR methods is CMP [13]. This compound is degraded very rapidly in soil -it is very unlikely to be encountered in waste from DMR methods even after short periods of interment.…”