Profiling ephedrine prepared from N-methylalanine via the Akabori-

Momotani Reaction

Alexandra Doddridge1,2, Michael Collins1 and Helen Salouros*1

1. National Measurement Institute, Riverside Corporate Park, North Ryde, Sydney,

Australia.
2. Centre for Forensic Science, University of Technology, Sydney Broadway, NSW,
Australia.

ABSTRACT:
Novel methods for synthesising methylamphetamine precursors are appearing in clandestine

laboratories within Australia. One such laboratory involved the synthesis of ephedrine from

N-methylalanine and benzaldehyde via the Akabori-Momotani reaction. This paper presents

chiral and stable isotope ratios of ephedrine synthesised via this method, along with a

chemical profile of methylamphetamine produced from this ephedrine. Based on the chiral

results and the 13C, 15N and 2H values it is possible to distinguish ephedrine made via the

Akabori-Momotani reaction from ephedrine of a “natural”, “semi-synthetic” or “fully-

synthetic” origin. Methylamphetamine and ephedrine samples synthesised from

benzaldehyde having an enriched 2H value (ie > 0‰), via the Akabori-Momotani reaction,

had an isotopic profile which set them apart from all other methylamphetamine samples. It

was noted however that using stable isotope ratios alone to determine the precursor of

methylamphetamine is limited; they could not with confidence differentiate between

methylamphetamine and ephedrine synthesised from benzaldehyde having a depleted 2H

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lead to differences between this version and the Version of Record. Please cite this article as
doi: 10.1002/dta.2239

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value (ie <0‰) from other ephedrine sources and phenyl-2-propanone based

methylamphetamine samples profiled.

KEYWORDS: Forensic science; Stable isotope ratios; Chemical profiling; Isotope Ratio
Mass Spectrometry (IRMS); Ephedrine; Pseudoephedrine; Methylamphetamine

Introduction

Ephedrine/pseudoephedrine is one of two major precursors used to manufacture illicit

methylamphetamine, with around 48 tonnes seized globally each year.[1] Approximately 80%

of methylamphetamine samples profiled in the author’s laboratory during the 2016-2017

calendar years were produced from ephedrine/pseudoephedrine. Identifying the precursor

chemicals used in methylamphetamine manufacture can aid law enforcement in its efforts to

disrupt manufacture and trafficking of this drug.

Ephedrine and pseudoephedrine are obtained industrially by three main processes: (i)

‘natural’ – extracted from the Ephedra plant; (ii) ‘semi-synthetic’ – fermentation of pyruvic

acid with benzaldehyde in the presence of pyruvate decarboxylase; and (iii) ‘fully-synthetic’

– prepared by the bromination of propiophenone, followed by amination then finally a

reduction step.[2,3]

While most industrial ephedrine and pseudoephedrine are made by these three routes many

other processes can be used. One such process is the Akabori-Momotani reaction. N-

Methylalanine is condensed with benzaldehyde to give a mixture of

ephedrine/pseudoephedrine (Figure 1).[4] Synthesis details for manufacturing N-

[5]
methylalanine and ephedrine/pseudoephedrine are discussed on internet forums and in

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Uncle Fester’s ‘Secrets of Methamphetamine Manufacture’.[6] Alanine and N-methylalanine

have also been identified at clandestine laboratories in Australia.[7] N-Methylalanine can be

purchased online from different chemical suppliers at an affordable price; for example this

laboratory purchased 1 kg of N-methylalanine for AUD$240, which could theoretically yield

1.6 kg of ephedrine/pseudoephedrine or 1.8 kg of methylamphetamine hydrochloride. In 2014

two border seizures of N-methylalanine were submitted to this laboratory. For these reasons,

we decided to investigate establishing a chemical profile for methylamphetamine that might

be prepared this way. This paper describes the synthesis of ephedrine via the Akabori-

Momotani reaction and its subsequent chemical and stable isotopic profiling.

Experimental

Reagents and Chemicals

All reference materials, internal standards and surrogate standards used in the chemical

profiling of ephedrine and methylamphetamine were obtained from the reference collection

of the National Measurement Institute, Australia (NMIA).

Analytical grade ethyl acetate, chloroform, dichloromethane, diethyl ether, glacial acetic acid

(100%) and hydrochloric acid (36%) were all obtained from Merck (Kilsyth, Vic, Australia).

1,4-Dioxane (Product #: 360481), benzaldehyde (purified by redistillation; Product #418099,

Lot #06396HMV and Lot #99696DJ; 98+%), D,L-alanine (Product #A7502; ≥99%),

iodomethane (Product #I8504, Lot STBF2417V and 35H3425), iodomethane (product

#67692, Lot SHBD5209V), L-alanine (Product #05130; ≥99%), L-alanine (Product #A7627;

≥98%), N-methyl-D,L-alanine (Product #M0506), trifluoroacetic acid (Product #302031;

99+%) were all purchased from Sigma Aldrich (Castle Hill, NSW, Australia). Di-tert-butyl

dicarbonate (Product #34660; ≥98%), benzaldehyde (puriss p.a.; Product #12010, Lot

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#1366836; ≥99.0%), benzaldehyde puriss standard for GC (Product #09143> 99.5%) and N-

methyl-L-alanine (Product #2676; ≥98%) were purchased from Fluka (Steinheim, Germany).

Iodomethane (Product #269, Lot 811415), hypophosphorous acid (50% w/w), iodine pellets,

sodium sulfate and sodium hydroxide pellets were purchased from UNIVAR Ajax Finechem

(Seven Hills, NSW, Australia). Sodium hydride (60% w/w dispersion oil) (Product #231-587-

3) was obtained from Lancaster Synthesis (Morcambe, England). Iodomethane (Product

#285853R, Lot 3690613334) and tetrahydrofuran (99%) were obtained from BDH

Laboratory Supplies (Poole, England). Benzaldehyde (Product #20863.29, Lot 290WR) was

purchased from VWR International (Vienna, Austria). N-methyl-D,L-alanine hydrochloride

(Product #S-295754) was purchased from Santa Cruz Biotechnology Pty Ltd (Dallas, TX,

USA). Two different batches of N-methyl-D,L-alanine were purchased online from Shanghai

Riche International Co., Ltd. (Shanghai, China) and Wuhan Hengheda Pharm Co., Ltd.

(Hubei, China). All reagents and chemicals were used without further purification.

Synthetic Chemistry

Synthesis of N-methylalanine

Step 1: Synthesis of 2-(N-(tert-butoxycarbonyl)amino)-alanine. Minor modifications

were made to the procedure outlined by Andrighetto et al.[8] L- or D,L-alanine (1 g) was

stirred in a mixture of 1,4-dioxane (22 mL) and H2O (11 mL) at 0°C. The pH was set at 9-10

using 10% NaOH (aq) solution. Boc2O (2.45 g) was added to the mixture and left to stir

overnight at room temperature. The mixture was washed with 50 mL of ethyl acetate and

acidified to pH 2 with 2M HCl (aq) and extracted with 2 x 100 mL of ethyl acetate. The ethyl

acetate extracts were dried over anhydrous sodium sulfate (Na2SO4) and the solvent removed

under reduced pressure leaving a white solid. The product was examined by GC-MS and 1H

NMR and its identity confirmed as 2-(N-(tert-butoxycarbonyl)amino)-alanine (1.9 g) by

[8] 1
comparison to literature. H NMR (d6 DMSO) δ 12.40 (br s, 1H, OH), 7.11 (d, 1H, 3JHH =

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7.56 Hz, NH), 3.92 (m, 1H, CH), 1.38 (s, 9H, t-Bu), 1.22 (d, 3H, 3JHH = 7.3 Hz, CH3). m/z:

189 (1), 144 (31), 116 (5), 88(21), 59 (56), 57 (100), 44 (44), 41(25), 29 (15).

Step 2: Synthesis of N-(tert-butoxycarbonyl)-N-methylalanine. 2-(N-(tert-

butoxycarbonyl)amino)-alanine was methylated using iodomethane and sodium hydride

following the method described by Malkov et al.[9] 2-(N-(tert-butoxycarbonyl)amino)-alanine

(1.9 g) was stirred in THF (20mL) on an ice bath under inert conditions to which a 10 molar

equivalent of methyl iodide was added in one addition. To this, a 10 molar equivalent of

sodium hydride 60% dispersion mineral oil was slowly added and the mixture left to stir at

room temperature for 24 hours. H2O (100 mL) was added to quench the reaction and diethyl

ether (200 mL) used to wash the reaction mixture. Using 5M HCl, the aqueous layer was

adjusted to pH 3. The solution was extracted with chloroform (2 x 100 mL). The combined

chloroform extracts were dried through Na2SO4 and the solvent evaporated under vacuum to

yield a white solid. The product was examined by GC-MS and 1H NMR and its identity

confirmed as N-(tert-butoxycarbonyl)-N-methylalanine (1.7 g) by comparison to literature. [8]

1
H NMR (d6 DMSO): δ 4.55/4.28 (s, 1H, CH), 2.74 (s, 6H, N-CH3), 1.38 (s, 18H, t-Bu), 1.29

(d, 6H, 3JHH= 7.41 Hz, CH3). m/z: 203 (1), 158 (7), 130 (5), 102 (77), 58(85), 57(100),

41(25).

Step 3: Synthesis of N-methylalanine. N-Methylalanine was prepared following the procedure

outlined by Andrighetto et al.[8] N-(tert-butoxycarbonyl)-N-methylalanine (1.7 g) was

dissolved in dichloromethane (DCM) (50 mL) and trifluoroacetic acid (15 mL) was added

drop-wise over a length of time. The mixture was left stirring for 24 hours at room

temperature before the DCM was removed under vacuum. To the resulting brown oil, DCM

(80 mL) was added and then removed under vacuum. This procedure was repeated three

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times to yield a white solid. The product was examined by GC-MS, 1H NMR and 13C NMR

and its identity confirmed as N-methylalanine (0.8 g) by comparison to a reference material.

1
H NMR (D2O): δ 8.46 (br s, 1H, small peak observed OH), 3.73 (q, 1H, 3JHH= 7.23 Hz, CH),

2.50 (br s, 1H, N-CH3), 1.31 (d,3H, 3JHH= 7.32 Hz, CH3). 13C NMR (D2O): 13.5 (CH3), 30.6

(CH), 56.6 (N-CH3), 172.3 (C=O). m/z: 103 (1), 88 (2), 58 (100), 56 (15), 42 (15).

Synthesis of Ephedrine

Ephedrine was synthesised using the procedure described by Painter and Pigou [7] with minor

modifications. A mixture of N-methylalanine (1 g) and benzaldehyde (1.2 mL) in DMSO was

stirred and heated at 130°C for 1 hour. Acetic acid solution (5%, 10.3 mL) was added to the

reaction mixture and refluxed. After 4 hours the mixture was allowed to cool. DCM (50 mL)

was added to the mixture and extracted with 3 x 50 mL of H2O. The pH of the aqueous phase

was adjusted to 10 with 10% NaOH (aq) and extracted with 3 x 60 mL of DCM. The

combined DCM extracts were dried over anhydrous sodium sulfate and evaporated to dryness

under reduced pressure yielding ephedrine/pseudoephedrine (0.79 g) as a white, waxy solid.

Synthesis of Methylamphetamine

Methylamphetamine was prepared via a modification of the method described by Salouros et

al.[10]

Sample Identification

Nuclear Magnetic Resonance Spectroscopy

Nuclear Magnetic Resonance (NMR) spectra of the samples were acquired as solutions in

D2O, CDCl3 or d6-DMSO using a Bruker Avance 500 MHz NMR Spectrometer equipped

with a Bruker BBFO 5 mm Probe. All spectra were acquired at a probe temperature of 295 K.

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Bruker TopSpin software was used to operate the NMR Spectrometer and process raw data.

A pulse program with a 90° pulse (13.2 s), a relaxation delay of 5 seconds and an

acquisition time of 4.4 seconds was used. Eight scans were acquired and the raw data

collected over 15 ppm into 64 K data points. Phase correction and baseline correction were
13
performed automatically and the integration width was established manually. C NMR

spectra were obtained at 125 MHz and 1024 scans were acquired with the raw data collected

over 260 ppm into 64K data points. A pulse program with a 30° pulse (3.3 s), a relaxation

delay of 2 seconds and an acquisition time of 4.4 seconds was used.

Gas Chromatography – Mass Spectrometry

Ephedrine, N-methylalanine and methylamphetamine were identified by Gas

Chromatography-Mass Spectrometry (GC-MS) by comparison to reference materials.

Analyses were performed on an Agilent 6890N GC interfaced with an Agilent 5973 MSD. A

30 m x 0.25 mm x 0.25 m HP-5MS column was employed using helium carrier gas in the

constant flow rate mode. Injection port temperature was 240°C and the MS interface

temperature was 300°C. The oven temperature program was 55°C (hold for 3 minutes),

ramped at 30°C/min to 300°C (no hold), and ramped at 20°C/min to 325°C (hold for 3

minutes). Injections (1 L) were made in pulsed splitless mode and a mass range of m/z 40 to

500 was scanned.

Gas Chromatography – Flame Ionisation Detection

The purities of ephedrine and methylamphetamine were determined by Gas Chromatography-

Flame Ionisation Detection (GC-FID), using a five point calibration curve and certified

reference materials of ephedrine and methylampehtamine, with methylephedrine and

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phenethylamine used as internal standards respectively, as described in earlier work. [2] Each

of the ephedrine and methylamphetamine samples produced in this work had a purity of

greater than 95%.

Enantiomeric composition by Capillary Electrophoresis

The enantiomeric composition of ephedrine samples (%, w/w) was determined using an

Agilent Technologies 7100 capillary electrophoremeter (CE) with photodiode array detector

(190-400nm) at a wavelength of 195nm. Samples were separated using an Agilent HPCE

standard capillary (i.d. 50 μL x 56 cm) using a DEA custom buffer (MicroSolv) at an applied

voltage of 30 kV at 15 ºC. Data was acquired and reprocessed using 3D-CE Chemstation

software version B.03.01. Methods were based on those published by Lurie et al.[11-12]

Approximately 4 mg of ephedrine or methylamphetamine HCl was dissolved in 5 mL of

DEA custom run buffer solution and further diluted with the buffer and N-

methylhomoveratrylamine internal standard solution (~2 mg/mL in custom run buffer) to

achieve a final concentration of 0.8 mg/mL. A mixed standard solution of d-ephedrine, l-

ephedrine, d-pseudoephedrine, l-pseudoephedrine and N-methylhomoveratrylamine, were

used to identify and determine the isomeric composition.

Stable Isotope Ratio Mass Spectrometry

Measurements of the stable isotope ratios of carbon (13C), nitrogen (15N) and hydrogen

(2H) of the precursor, intermediates, reagents and ephedrine products described here were

determined using the isotope ratio mass spectrometry methods described in our previous

work.[2, 13-14]
Calibration and quality control of Elemental Analyser/Thermal Conversion –

Isotope Ratio Mass Spectrometry (EA/TC-IRMS) measurements is outlined in our previous

work and below.[2]

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The ability to determine isotopic fractionation patterns in the synthesis of ephedrine and

methylamphetamine as being comparable or distinct is dependent on an estimation of

measurement uncertainty. This was performed by combining bias and precision contributions

in quadruplicate according to the GUM uncertainty framework.[15-16] For a 95% confidence

interval (k=2) an expanded uncertainty (U) for 13C, 15N and 2H measurements was

estimated to be ±0.4‰, ±0.5‰ and ±4‰, respectively. These uncertainty estimates were

considered to be fit-for-purpose based on the range of values recorded for two high purity

methylamphetamine HCl quality control samples analysed every 3 samples.

Results and Discussion

Ephedrine/pseudoephedrine was synthesised 37 times from N-methylalanine and

benzaldehyde using the Akabori-Momotani reaction. Five different sources of N-

methylalanine and four different benzaldehyde sources were employed in these reactions

(Table 1). The ephedrine/pseudoephedrine synthesised samples were profiled using stable

isotope ratio mass spectroscopy to determine the carbon, hydrogen and nitrogen stable

isotope ratios, and capillary electrophoresis to determine the chirality of the

ephedrine/pseudoephedrine. The results from each of these analyses are shown in Table 1 and

Table 2 respectively.

The 13C value for the ephedrine/pseudoephedrine synthesised from N-methylalanine ranged

between -29.7‰ to -38.4‰ (Table 1). A 13C value more depleted than -32‰ for

methylamphetamine samples prepared from ephedrine/pseudoephedrine have not been

encountered in this laboratory nor known to have been reported in any peer-reviewed

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literature. [2-3, 13-14, 17-20]
Typically, a 13C value more depleted than -32‰ would indicate a

methylamphetamine sample synthesised from phenyl-2-propanone (P2P) which in turn was

synthesised from phenyl acetic acid.[20] The 13C value for ephedrine/pseudoephedrine

synthesised from N-methylalanine are unique to this synthetic pathway as far as

ephedrine/pseudoephedrine based methylamphetamine samples are concerned.

The 2H value for the ephedrine/pseudoephedrine synthesised from N-methylalanine ranged

between +335‰ to -96‰ (Table 1). Two main groups were observed in the 37

ephedrine/pseudoephedrine synthesised samples based on their 2H value; those depleted in

deuterium and those enriched in deuterium. The 2H value of the ephedrine/pseudoephedrine

produced via the Akabori-Momotani reaction is predominately influenced by the

benzaldehyde source. Previous studies have demonstrated that the enriched hydrogen isotope

ratio of benzaldehyde is conserved when used to synthesise ephedrine via the ‘semi-

synthetic’ procedure.[2, 13-14, 17]

In this paper, when N-methylalanine was reacted with a

deuterium enriched benzaldehyde source (Batches 2, 3 and 4 in Table 1) it formed

ephedrine/pseudoephedrine with 2H values ranging between +335‰ and +125‰. In the

cases where N-methylalanine was reacted with a deuterium depleted benzaldehyde source

(Batch 1 in Table 1), the ephedrine/pseudoephedrine samples had 2H values ranging

between -96‰ and -39‰.

The 15N value for the ephedrine/pseudoephedrine synthesised from N-methylalanine ranged

from +10.1‰ to -24.3‰, with the majority of the samples having a 15N value more depleted

than 0‰ (Table 1). The 15N value for these samples were however batch to batch dependant.

For example in Table 1 ephedrine/pseudoephedrine Synthesis Batch Number 32 and 33, are

both prepared from the same N-methylalanine source and benzaldehyde source and every

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attempt was made to use the same reaction conditions. The 15N value for Batch 32 is

different to that of Batch 33, i.e. the values lie outside the measurement uncertainty. This can

be explained in part if we consider the proposed mechanism for this reaction by Painter and

Pigou.[7] The first step is a nucleophilic addition reaction meaning kinetic fractionation would

be one reason for these observed isotopic differences in the 15N values. However the

observed differences in 15N values are large and could also be attributed to changes in the

synthesis parameters, though this requires further investigation.

Carbon and hydrogen isotopic variation was also observed between batches of

ephedrine/pseudoephedrine, including those where the same N-methylalanine and

benzaldehyde source were employed. For example ephedrine/pseudoephedrine Synthesis

Batch 1 through to Synthesis Batch 8 were made using the same N-methylalanine and

benzaldehyde source (see Table 1). The 13C values range from -30.7‰ to -33.1‰ and the

2H values range from -57‰ to -79‰. Whilst every attempt was made to control

experimental reaction parameters, including temperature of reaction, order of adding

reagents, the rate at which reagents where added and reaction time, isotopic variation was still

observed between the different batches. A plausible explanation for this is kinetic

fractionation resulting from the reaction mechanism. This essentially means that

discrimination between the different synthetic batches may be possible even where the same

precursor chemicals where employed. Information such as this would be of tactical value for

law enforcement.

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Six of the ephedrine hydrochloride samples prepared from N-methylalanine were converted

to methylamphetamine using a phosphorus/iodine procedure as outlined in the Experimental

Section. Table 3 shows the 13C, 15N and 2H values of the six methylamphetamine

samples. The stable isotope ratios of the methylamphetamine are comparable to those of the

ephedrine samples they were synthesised from. These results are consistent with previous

studies where ephedrine was converted to methylamphetamine and the stable isotope ratio

values correctly reflected the synthetic origin of the ephedrine.

Figure 2 shows the 13C versus 2H values for 3,500 methylamphetamine samples seized at

the Australian Border between 2010 and 2016. These samples were determined to be

synthesised from ephedrine/pseudoephedrine, by considering all three stable isotope ratios

together with information from other chemical profiling signatures including organic

impurity profiling, chiral analysis and elemental analysis. What is immediately apparent is

ephedrine/pseudoephedrine and methylamphetamine prepared from N-methylalanine stand

apart from methylamphetamine samples prepared from ephedrine/pseudoephedrine from a

semi-synthetic, fully-synthetic and natural origin. The 13C value of the samples prepared

from N-methylalanine are on average more depleted (average 13C = -31.5‰) than

methylamphetamine samples prepared from a natural source of ephedrine or synthetic source

of ephedrine (average 13C = -28.4‰). Ephedrine/pseudoephedrine and methylamphetamine

samples made using a deuterium enriched benzaldehyde source (Batches 2, 3 and 4 in Table

1), resulted in ephedrine/pseudoephedrine and methylamphetamine samples with 2H values

ranging from +335‰ to +125‰. These samples are easily discriminated from other samples

as shown in Figure 2 owing to the unique combination of a depleted carbon isotope ratio (i.e.

less than -30‰) and enriched hydrogen isotope ratio. Ephedrine/pseudoephedrine and

methylamphetamine prepared from benzaldehyde having a negative hydrogen isotope ratio

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are not as easily discriminated from other batches of ephedrine and methylamphetamine,

namely those derived naturally from the Ephedra plant or made synthetically from

propiophenone.

Figure 2 also shows of the 3,500 methylamphetamine samples profiled in this laboratory only

two had 13C values that were more depleted than -32‰. In the case of the 37 ephedrine and

six methylamphetamine samples synthesised via the Akabori-Momotani reaction all were

determined to have 13C values less than -30‰ ± 0.4‰. Ephedrine/pseudoephedrine samples

made via the Akabori-Momotani synthetic pathway, can easily be distinguished from

ephedrine/pseudoephedrine made via the semi-synthetic pathway based on the carbon stable

isotope ratios. The former samples have a more depleted 13C value, i.e. less than -30‰ ±

0.4‰, than the latter samples, i.e. greater than -26‰ ± 0.4‰).

The depleted carbon isotope ratios observed in the ephedrine/pseudoephedrine samples

prepared from N-methylalanine can be attributed to its precursor N-methylalanine. Table 4

lists the 13C, 15N and 2H values of fifteen different sources of N-methylalanine. The 13C

values for these samples ranged from -31.2‰ to -50.7‰. Eight of these sources were N-

methylalanine samples synthesised in this laboratory using a procedure published by

Andrighetto et al.[8] Figure 3 shows the three step process by which N-methylalanine was

prepared from alanine. The negative 13C value observed in the final N-methylalanine

samples made via this route is primarily attributed to the starting material methyl iodide.

Table 5 shows the 13C value for seven methyl iodide samples sourced from different

suppliers as well as published values.[21] Each of these methyl iodide sources has 13C values

ranging between -39.7‰ and -80.7‰, and explains the depleted carbon value observed in the

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N-methylalanine and consequently the ephedrine/pseudoephedrine and methylamphetamine

products.

Figure 4 is a plot of 13C versus 2H values for 840 methylamphetamine samples seized at the

Australian Border between 2010 and 2016. These methylamphetamine seized samples were

determined to be synthesised from P2P using a combination of organic impurity profiling,

chiral analysis, elemental analysis and stable isotope ratio analysis. In Figure 4, the

ephedrine/pseudoephedrine and methylamphetamine samples synthesised from N-

methylalanine and a deuterium enriched benzaldehyde source (purple and orange diamonds

respectively) stand apart quite clearly from the seized methylamphetamine samples

determined to be made from P2P (yellow diamonds). Ephedrine/pseudoephedrine and

methylamphetamine samples synthesised from N-methylalanine and a deuterium depleted

benzaldehyde source (green and orange diamonds respectively) cannot be discriminated from

P2P based methylamphetamine samples (yellow diamonds) on stable isotope ratios alone.

The 37 synthesised ephedrine/pseudoephedrine samples were also analysed using CE to

determine the chiral composition of the ephedrine/pseudoephedrine samples (Table 2). All of

the ephedrine/pseudoephedrine samples were determined to be a mixture of the four

stereoisomeric combinations of ephedrine and pseudoephedrine, i.e. d- and l-ephedrine and d-

and l-pseudoephedrine. These results are in agreement with previously published work.[7] The

purity values ranged from 18.5% to 34.8% for d-ephedrine, 18.8% to 35.2% for l-ephedrine,

15.4% to 33.1% for d-pseudoephedrine and 15.1% – 29.6% for l-pseudoephedrine.

Irrespective of the stereoisomeric combination of ephedrine/pseudoephedrine formed in the

Akabori-Momotani reaction, the subsequent conversion to methylamphetamine would result

in racemic methylamphetamine (Table 2).

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Chiral analysis of the 6 methylamphetamine samples synthesised from the ephedrine made

via the Akabori-Momotani reaction, showed the methylamphetamine to be racemic,

confirming our earlier statement (see Table 3). This result highlights the importance of

marrying results from multiple profiling methods.[14] A chiral analysis result of racemic

methylamphetamine, if considered in isolation, could be wrongly interpreted as

methylamphetamine having been produced from P2P via reductive amination. Using a

combination of isotopic profiling, chiral analysis, elemental analysis and organic impurity

profiling, sufficient information should be available for a forensic practitioner to determine

the synthetic origin of the methylamphetamine precursor.

Conclusions

In this paper we have presented an isotopic and chiral profile for ephedrine/pseudoephedrine

synthesised from N-methylalanine via the Akabori-Momotani reaction. The results show that

methylamphetamine produced from this synthetic route show distinct chemical characteristics

to set it apart from methylamphetamine prepared from ephedrine/pseudoephedrine sourced

from other synthetic pathways. Methylamphetamine samples prepared from

ephedrine/pseudoephedrine synthesised via the Akabori-Momotani reaction have a more

depleted 13C value, i.e. less than -30‰ ± 0.4‰, than methylamphetamine samples

synthetised from ephedrine/pseudoephedrine sourced from a ‘semi-synthetic’, ‘fully-

synthetic’ or ‘natural’ origin.

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References

1. Australian Crime Commission. Illicit Drug Data Report 2013-14. Canberra,

Australia. 2015.
2. Collins M, Cawley AT, Heagney AC, Kissane L, Robertson, J, Salouros H. 13C, 15N
and 2H isotope ratio mass spectrometry of ephedrine and pseudoephedrine:
Application to methylamphetamine profiling. Rapid Commun Mass Spectrom 2009
Jul;23(13):2003-10. DOI: 10.1002/rcm.4109
3. Makino Y, Urano Y, Nagano T. Investigation of the origin of ephedrine and
methamphetamine by stable isotope ratio mass spectrometry: a Japanese experience.
Bull Narc 2005;57(1-2):63-78.
4. Akabori S, Momotani K. On the New Reaction Giving Alcamines of Ephedrine and
Adrenaline Series. Nippon Kagaku Kaishi. 1943;64(5):608-11.
5. Various Authors. N-Methyl-d,l Alanine Discussion Board. 2011. Available from:
http://www.sciencemadness.org/talk/viewthread.php?tid=16129. Accessed 18/06/17.
6. Fester U. Secrets of Methamphetamine Manufacture: Including Recipes for MDA,
Ecstacy and Other Psychedelic Amphetamines. 8th Ed. Loompanics Unlimited.
2009:184-187.
7. Painter B, Pigou PE. The Akabori-Momotani Reaction: The next frontier in Illicit
drug manufacture? J Clandest Lab Invest Chem Assoc 2012;22: 6-14.
8. Andrighetto LM, Pfeffer FM, Stevenson PG, et al. Three step synthesis of N-
methylalanine- A precursor to ephedrine, pseudoephedrine and methamphetamine. J
Clandest Lab Invest Chem Assoc 2014;24:44-48.
9. Malkov AV, Vrankova K, Cerny M, Kocovsky P. On the Selective N-Methylation of
BOC-Protected Amino Acids. J Org Chem 2009;74:8425-27. DOI:
10.1021/jo9016293
10. Salouros H, Collins C, Cawley A, Longworth M. Methylamphetamine synthesis:
Does and alteration in synthesis conditions affect the 13C, 15N and 2H stable
isotope ratio value of the product?. Drug Testing and Analysis 2012;4:330-336. DOI
10.1002/dta.321
11. Lurie IS, Bethea MJ, McKibben TD, et al. Use of Dynamically Coated Capillaries for
the Routine Analysis of Methamphetamine, Amphetamine, MDA, MDMA, MDEA
and Cocaine using Capillary Electrophoresis. J Forensic Sci 2001;46:1025-32. DOI:
10.1520/JFS15096J.
12. Lurie IS, Bozenko Jr. JS, Miller LL, Erin E, Miller SJ. Chiral Separation of
Methamphetamine and Related Compounds using Capillary Electrophoresis with
Dynamically Coated Capillaries. Microgram J 2011;8,:24.
13. Salouros H, Sutton GJ, Howes J, Hibbert DB, Collins M. Measurement of stable
isotope ratios in methylamphetamine: A link to its precursor source. Anal Chem 2013;
85:9400-08. DOI: 10.1021/ac402316d.
14. Collins M, Salouros H. A review of some recent studies on the stable isotope profiling
of methamphetamine: Is it a useful adjunct to conventional chemical profiling? Sci
Justice 2015;55:2-9. DOI: 10.1016/j.scijus.2014.08.006.
15. Eurachem/Citac Guide. Quantifying uncertainty in analytical measurement (2nd edn),
2000. Available: http://www.eurachem.org/guides/pdf/QUAM2000-1.pdf.

This article is protected by copyright. All rights reserved.

16. Joint Committee for Guides in Metrology Evaluation of Measurement Data: Guide to
the Expression of Uncertainty in Measurement; JCGM 100:2008; BIPM: Sevres,
2008. (www.bipm.org/en/publications/guides/gum.html)
17. Matsumoto T, Urano Y, Makino Y, et al. Evaluation of Characteristic Deuterium
Distributions of Ephedrines and Methamphetamines by NMR spectroscopy for Drug
Profiling. Anal Chem 2008;80: 1176-81. DOI: 10.1021/ac701639j.
18. Kurashima N, Makino Y, Urano Y, Sanuki K, Ikehara Y, Nagano T. Use of stable
isotope ratios for profiling ephedrine samples: Application of hydrogen isotope ratios
in combination with carbon and nitrogen. Forensic Sci Int 2009;189:14-18. DOI:
10.1016/j.forsciint.2009.04.011.
19. Kurashima N, Makino Y, Sekita S, Urano Y, Nagano T. Determination of origin of
ephedrine used as precursor for illicit methamphetamine by carbon and nitrogen
stable isotope ratio analysis. Anal Chem 2004;76:4233-36.
20. Toske SG, Morello DR, Berger JM,Vazquez ER. The use of 13C isotope ratio mass
spectrometry for methamphetamine profiling: comparison of ephedrine and
pseudoephedrine-based samples to P2P-based samples. Forensic Sci Int 2014;234:1-6.
DOI: 10.1016/j.forsciint.2013.10.022.
21. Schimmelmann A. Alphabetical Listing of all reference materials. University of
Indiana. 2015. Available from:
http://pagesiuedu/~aschimme/files/alphabetical%20list%20of%20all%20reference%2
0materialspdf2015

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 OH OH
CH 3

CH3 CH3
OH O 1. DMSO, 
HN + +
2. Acetic acid, ref lux 4h HN HN
CH 3 O
CH3 CH3

N-methylalanine benzaldehyde ephedrine pseudoephedrine

Figure 1: Synthesis scheme for the preparation of ephedrine/pseudoephedrine via the Akabori-
Momotani Reaction

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Figure 2: Carbon vs hydrogen stable isotope ratios of seized ephedrine/pseudoephedrine based
methylamphetamine, synthesised methylamphetamine and ephedrine/pseudoephedrine samples
via Akabori-Momotani reaction

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 CH 3
O CH 3 i) ICH3 O CH 3 CH 3
Dioxane: water (2:1)
OH Boc2O, 3 h, 25 oC ii) NaH 20% TFA
OH N 2, 0oC OH DCM , 18h, r.t. OH
H 2N
O N O N HN
H
O
O CH 3 O CH3 O

alanine N-Boc2O protected alanine N -methylalanine

Methylated N-Boc2O protected alanine

Figure 3: Synthesis scheme for the preparation of N-methylalanine

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Figure 4: Carbon vs hydrogen stable isotope ratios of seized P2P based methylamphetamine,
synthesised methylamphetamine and ephedrine/pseudoephedrine samples via Akabori-Momotani
reaction

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Table 1: Carbon, nitrogen and hydrogen stable isotope ratios for ephedrine synthesised from N-
methylalanine via the Akabori-Momotani Reaction

N-methylalanine Benzaldehyde Ephedrine/Pseudoephedrine Ephedrine/Pseudoephedrine

source source Synthesis Batch No 15
 NAir
13
 CVPDB
2
 HVSMOW
(±0.5‰)* (±0.4‰)* (±4‰)*
Internet Purchase Batch 1 1 -6 -31.3 -60
Batch 1 Fluka 2 -2.1 -30.8 -60
C = -31.5‰ Lot #1366836 3 -10.8 -33.1 -77
N = -8.7‰ C = -25.1‰ 4 -3.1 -30.9 -58
H = -78‰ H = -52‰ 5 -4.3 -32.4 -79
6 -0.1 -30.9 -62
7 -7.2 -31.5 -66
8 0.3 -30.7 -57
Batch 2 9 0.7 -30.6 216
Sigma 10 -2.5 -30.1 247
Lot #06396HMV 11 -5.9 -30.1 245
C = -25.3‰
H = +613‰
Batch 3 12 -1.7 -30.9 178
Sigma 13 -3.6 -30.8 169
Lot #99696DJ
C = -26.3‰
H = +552‰
Internet Purchase Batch 1 14 -0.4 -31.2 -59
Batch 2 15 -14.4 -32.9 -72
C = -31.4‰ 16 -12.2 -31.2 -70
N = -6.0‰ 17 3.1 -30.9 -56
H = -69‰ 18 0.9 -31.0 -54
19 -0.6 -31.1 -59
20 -4.3 -31.0 -63
21 0.8 -30.9 -53
22 -0.5 -30.9 -58
Batch 2 23 -9.6 -29.9 205
24 -6.1 -30.0 207
25 -0.8 -30.4 231
26 0.5 -29.8 265
27 5.9 -29.7 258
Batch 3 28 3.6 -30.9 184
29 4.8 -30.5 184

Batch 4 30 -14.5 -30.6 170

VWR 31 -24.3 -30.9 149
Lot #290WR
C = -25.6‰
H = +539‰
Sigma-Aldrich Batch 1 32 -2.3 -38.4 -55
C = -50.7‰ 33 10.1 -37.9 -39
N = -0.7‰
H = -12‰
Fluka Batch 1 34 -8.5 -37.7 -96
C = -43.3‰
N = -4.7‰ Batch 2 35 -3.7 -34.7 335
H = -155‰
Batch 4 36 2.3 -34.9 125

Seizure 1 Batch 1 37 -9.9 -32.2 -66

C = -31.6‰
N = -9.1‰
H = -90‰

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Table 2: Chiral analysis results for ephedrine synthesised from N-methylalanine via the Akabori-
Momotani Reaction

Ephedrine/Pseudoephedrine Ephedrine (%) Pseudoephedrine (%) Predicted Meth (%)

Synthesis Batch No + - + - d l
d l d l
1 21.9 22.1 30.3 25.7 52.4 47.6
2 28.2 28.5 23.1 20.2 51.6 48.4
3 22.3 22.7 29.1 25.8 51.8 48.2
4 27.0 27.2 24.5 21.4 51.6 48.4
5 18.5 18.8 33.1 29.6 51.9 48.1
6 29.9 29.3 21.7 19.1 51.0 49.0
7 30.0 30.2 21.2 18.6 51.4 48.6
8 29.0 29.4 22.0 19.6 51.4 48.6
9 22.6 23.8 28.6 25.0 52.4 47.6
10 25.0 25.3 26.6 23.1 51.9 48.1
11 24.5 24.9 27.3 23.3 52.2 47.8
12 27.9 28.1 22.6 21.3 50.7 49.3
13 22.2 22.6 28.3 26.9 50.9 49.1
14 24.8 25.2 26.3 23.7 51.5 48.5
15 29.4 29.5 21.8 19.3 51.3 48.7
16 26.3 26.9 24.7 22.1 51.6 48.4
17 24.5 24.7 26.7 24.2 51.3 48.7
18 26.7 28.5 23.3 21.5 51.8 48.2
19 29.0 29.5 22.3 19.3 51.8 48.2
20 31.1 31.9 20.2 16.7 52.1 47.8
21 31.1 31.3 19.2 18.4 50.5 49.5
22 29.7 30.4 23.4 16.6 53.7 46.3
23 25.8 26.3 25.3 22.6 51.6 48.4
24 25.7 26.3 25.2 22.8 51.5 48.5
25 34.8 35.2 15.4 15.1 50.6 49.9
26 26.1 26.5 25.2 22.0 51.7 48.2
27 25.9 26.4 25.2 22.4 51.7 48.3
28 27.4 27.4 22.8 22.4 50.3 49.8
29 28.5 28.9 21.8 20.8 50.7 49.3
30 29.8 29.8 20.8 19.6 50.6 49.4
31 28.3 28.7 22.1 20.9 50.8 49.2
32 29.4 30.1 21.4 19.0 51.5 48.5
33 23.5 23.7 26.9 25.9 50.6 49.4
34 24.5 25.2 26.7 23.5 51.5 48.4
35 23.5 23.7 26.9 25.9 50.6 49.4
36 23.5 23.4 27.3 25.7 50.7 49.2
37 28.2 28.7 23.1 20.9 51.8 49.1

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 Table 3: Stable isotope ratios and Chirality of Methylamphetamine synthesised from Ephedrine
which in turn was synthesised from N-methylalanine via the Akabori-Momotani Reaction

Ephedrine/Pseudoephedrine Ephedrine/Pseudoephedrine Methylamphetamine

Synthesis Batch No. 15 13 2 15 13 2
 NAir  CVPDB  HVSMOW  NAir  CVPDB  HVSMOW d l
(±0.5‰)* (±0.4‰)* (±4‰)* (±0.5‰)* (±0.4‰)* (±4‰)* (%) (%)
8 0.3 -30.7 -57 -3.6 -31.3 -106 50 50
9 0.7 -30.6 216 1.3 -30.2 175 51 49
10 -2.5 -30.1 247 -2.4 -30.0 231 50 50
11 -5.9 -30.1 245 -4.7 -30.2 200 50 50
26 0.5 -29.8 265 -3.2 -30.1 211 50 50
30 -14.5 -30.6 170 -12.3 -30.8 110 50 50

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Table 4: Carbon, nitrogen and hydrogen stable isotope ratios of N-methylalanine

Alanine Methyl N-methylalanine

N-methylalanine
source Iodide
Batch No 15
 NAir
13
 CVPDB
2
 HVSMOW
source (±0.5‰)* (±0.4‰)* (±4‰)*

Internet Purchase Batch na na -8.7 -31.5 -78

1
Internet Purchase Batch na na -6.0 -31.4 -69
2
Sigma-Aldrich na na -0.7 -50.7 -12
(Product # M0506 Lot #
BCBK1659V)
Fluka na na -4.7 -43.3 -155
(Product # 2676 Lot #
BCBK7064V)
Santa Cruz na na -10.7 -31.2 -80
Biotechnology
(Product # S-295754 Lot
# C0315)
Seizure 1 na na -9.1 -31.6 -90

Seizure 2 na na -9.2 -31.6 -79

Synthesis Batch 1 Batch 1 Batch 1 -3.6 -37.1 -90

L-alanine C = -53.9‰
Synthesis Batch 2 C = -18.7‰ Batch 2 -2.6 -42.8 -121
N = 1.2‰ C = -80.7‰
Synthesis Batch 3 H = -138‰ Batch 3 -0.9 -37.6 -120
C = -57.1‰
Synthesis Batch 4 -2.1 -38.1 -116

Synthesis Batch 5 Batch 2 -2.5 -36.0 -64

D,L-alanine
Synthesis Batch 6 C = -14.7‰ -2.9 -36.5 -59
N = -0.7‰
H = -54‰
Synthesis Batch 7 Batch 3 -8.4 -38.5 -123
L-alanine
Synthesis Batch 8 C = -19.9‰ -9.5 -38.7 -124
N = -7.6‰
H = -148‰

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Table 5: Survey of carbon stable isotope ratios of Methyl Iodide

Methyl Iodide 13CVPDB

(±0.4‰)*
UNIVAR (Product # 269 Lot #811415) -53.9

Sigma (Product # 67692 Lot #SHBD5209V) -57.1

Sigma (Product # 18507 Lot #35H3424) -80.7

Sigma (Product # 18507 Lot #STBF4417V) -45.6

BDH Laboratory (Product #285853R Lot -39.7

#S3690613334)
Indiana University Standard #1 [21] -54.6

Indiana University Standard #2 [21] -54.8

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