Identification and synthesis of di-(1-phenylisopropyl)methylamine, an impurity in illicit methamphetamine

Characterization of route specific impurities found in methamphetamine synthesized by the Leuckart and reductive amination methods

Impurity profiling of seized methamphetamine can provide very useful information in criminal investigations and, specifically, on drug trafficking routes, sources of supply, and relationships between seizures. Particularly important is the identification of “route specific” impurities or those which indicate the synthetic method used for manufacture in illicit laboratories. Previous researchers have suggested impurities which are characteristic of the Leuckart and reductive amination (Al/Hg) methods of preparation. However, to date and importantly, these two synthetic methods have not been compared in a single study utilizing methamphetamine hydrochloride synthesized in-house and, therefore, of known synthetic origin. Using the same starting material, 1-phenyl-2-propanone (P2P), 40 batches of methamphetamine hydrochloride were synthesized by the Leuckart and reductive amination methods (20 batches per method). Both basic and acidic impurities were extracted separately and analyzed by GC/MS. From this controlled study, two route specific impurities for the Leuckart method and one route specific impurity for the reductive amination method are reported. The intra- and inter-batch variation of these route specific impurities was assessed. Also, the variation of the “target impurities” recently recommended for methamphetamine profiling is discussed in relation to their variation within and between production batches synthesized using the Leuckart and reductive amination routes.

New impurity profiles of recent Australian imported ‘ice’: Methamphetamine impurity profiling and the identification of (pseudo)ephedrine and Leuckart specific marker compounds

Determination of the synthetic route in methamphetamine profiling relies on the identification of key, route specific marker impurity compounds. Impurity profiling of recent crystalline methamphetamine ('ice'), seized by the Australian Federal Police at the Australian border in 2003-2004, identified route specific marker compounds normally associated with two different synthetic approaches in the same samples. Impurities consistent with the ephedrine route included 1,2-dimethyl-3-phenyl aziridine (I), 1,3-dimethyl-2-phenylnaphthalene (VIII) and 1-benzyl-3-methylnaphthalene (IX), alongside N-formylmethamphetamine (V), N,N-di-(beta-phenylisopropyl)amine (XII) and N,N-di-(beta-phenylisopropyl)methylamine (XIII), N-benzoylamphetamine (XIV) and N,N-di-(beta-phenylisopropyl)formamide (XV) commonly associated with the Leuckart route and/or reductive amination. A non-synthetic process related origin of low-level N-formylmethamphetamine is proposed.

Synthesis of standards of the most important markers of Leuckart p-methoxymethamphetamine (PMMA). Examination of the influence of experimental conditions and a drug diluent on SPE/TLC profiling

The synthesis of characteristic markers of PMMA obtained by Leuckart method was described. The effectiveness of a procedure of SPE/TLC screening profiling of impurities was studied on the basis of selected impurities. The influence of glucose (a drug diluent) on the profile quality was investigated. The intermediate product (characteristic for the Leuckart synthesis) N-formyl-p-methoxymethamphetamine (1) and by-products: N-formyl-p-methoxyamphetamine (2), p-methoxyamphetamine (3), N,N-dimethyl-p-methoxyamphetamine (4), (RS) and (RR/SS) diastereoisomers of bis(1-methyl-2-(4-methoxyphenyl)ethyl)amine (meso-5 and rac-5), (RS) and (RR/SS) diastereoisomers of N-methyl-bis(1-methyl-2-(4-methoxyphenyl)ethyl)amine (meso-6 and rac-6), N-methyl-1,3-bis(4-methoxyphenyl)propane-2-amine (7) were synthesized. The substrate p-methoxyphenylacetone and the impurities 1 and 4 were used in the study of influence of experimental conditions and glucose on the profiling process and results. The experiments were carried out according to a 2(4) factorial design. The proposed criterions of the profile quality are based on matrix presentation of TLC patterns. They take into account the number of spots revealed, differences between R(f) values and intensity of fluorescence, simultaneously.

Identification and synthesis of some contaminants present in 4-methoxyamphetamine (PMA) prepared by the Leuckart method

The clandestine synthesis of ring and side chain modified phenylisopropylamines continues to be a major source of these drugs of abuse. One method used for the synthesis of the amphetamine and related compounds involves the treatment of the appropriate ketone with formamide or ammonium formate followed by acid hydrolysis of intermediate N-formyl derivative. In this paper the synthesis of 4-methoxyamphetamine (PMA, 1) by the Leuckart method is investigated. The identification by means of gas chromatography-mass spectrometry (GC-MS) of methoxy derivative of N-(beta-phenylisopropyl)benzaldimine 9, methoxy derivative of N-(beta-phenylisopropyl)benzyl methyl ketimine 5, 1-(4-methoxyphenyl)-N-(4-methoxybenzyl)-2-propanamine 10, (RR/SS) and (RS) 1-(4-methoxyphenyl)-N-[2-(4-methoxyphenyl)-1-methylethyl]-2-propanamine 6a-6c, (RR/SS) and (RS)-1-(4-methoxyphenyl)-N-methyl-N-[2-(4-methoxyphenyl)-1-methylethyl]-2-propanamine 7a-7c, (RR/SS) and (RS)-1-(4-methoxyphenyl)-N-formyl-N-[2-(4-methoxyphenyl)-1-methylethyl]-2-propanamine 8a-8c in crude PMA, are reported. The identity of these compounds was confirmed by independent synthesis of reference compounds. The NMR, MS, IR data, stereochemistry and some chromatographic properties of synthesized compounds are discussed. Finally, the results of the GC-MS analysis of illicitly prepared tablets, containing PMA 1 and 4-methoxymethamphetamine (PMMA, 2), are outlined. The presence of 4-methoxydimethylamphetamine 11, 4-methoxyethylamphetamine 12, and 4-hydroxymethamphetamine 13 are reported in these tablets. The identity of 2, 11, and 12 was confirmed by their independent synthesis.

Identification of impurities and statistical classification of methamphetamine tablets (Ya-Ba) seized in Thailand

Impurity profiles of methamphetamine tablets seized in Thailand have been investigated. The samples are extracted with small amounts of ethyl acetate under alkaline condition and the extracts are analyzed by capillary gas chromatography. Nine compounds (1,2-dimethyl-3-phenylaziridine, ephedrine, methylephedrine, N-formylmethamphetamine, N-acetylmethamphetamine, N-formylephedrine, N-acetylephedrine, N,O-diacetylephedrie, methamphetamine dimer) are identified as impurities in methamphetamine tablet. Caffeine and ethyl vanillin are also detected as diluents and/or adulterants, and acetylcodeine monoacetylmorphine and diacetylmorphine are contained in many samples. In addition, trans-3,4-dimethyl-5-phenyl-2-oxazolidone is newly found as an impurity. For characterization and comparison of methamphetamine tablet exhibits, intensely and commonly detectable nine peaks are selected as the factor for multivariate analysis. The procedures reported here permit classification of 250 analyzed exhibits into five groups and characterization of classified groups.

Alpha-phenylethylamine in illegally produced amphetamine

The possibility of simultaneous synthesis of alpha-phenylethylamine and amphetamine from mixture of acetophenone and benzylmethylketone was studied. The structures of specific impurities were predicted and these compounds were synthesized and finally found in reaction mixtures, as well as in the final product. The data collected by gas chromatography, proton and carbon magnetic resonance, Fourier transform infrared spectrometry and mass spectrometry are presented.

Illicit methamphetamine: analysis, synthesis, and availability

Methamphetamine has been marketed illicitly since the 1960s. Much of the street material was illicitly synthesized. Although methamphetamine quality was variable in the past decade, it has emerged since 1978 as the only street stimulant which is likely to contain what it purports to contain. Although there is a small volume of legitimate methamphetamine still made by the pharmaceutical industry, most material analyzed by street-drug laboratories appears to have been illegitimately synthesized and not diverted. For a decade, relatively little methamphetamine was submitted to street-drug analytical labs. In recent years, although the absolute volume of methamphetamine submissions changed little, this drug made up the bulk of alleged stimulant samples submitted to such facilities because of the paucity of amphetamine submissions. Methamphetamine synthesis and use appears to constitute a small but continuing portion of the illicit drug market.