Methamphetamine is produced using various routes from two predominant precursors, ephedrine/pseudoephedrine or phenyl-2-propanone (P2P). The multitude of synthetic routes results in many possible impurities (by-products or intermediates). Impurity profiling of methamphetamine by gas chromatography-mass spectrometry (GC–MS) is an important tool for the forensic chemist and investigators to assist in identification of the synthetic pathway and linking seizures. With the emergence of alternative routes, continued research into impurity profiles is important. One such alternative route is an ephedrine/pseudoephedrine-based pathway using the precursors typically associated with the phenyl-2-propanone (P2P) route, benzaldehyde and nitroethane. Benzaldehyde and nitroethane were condensed to form 2-nitro-1-phenyl-1-propanol. Subsequent reduction led to the corresponding 2-amino-1-phenyl-1-propanol. Cyclization-methylation with dimethyl carbonate to 3,4-dimethyl-5-phenyl-2-oxazolidinone, followed by catalytic hydrogenolysis or basic hydrolysis formed methamphetamine and ephedrine/pseudoephedrine, respectively. This paper presents the impurity profile of the alternative route. The conditions for the reduction of the intermediate 2-nitro-1-phenyl-1-propanol to 2-amino-1-phenyl-1-propanol was found to influence the by-products observed in the methamphetamine product. Notable by-products were amphetamine, N-ethylamphetamine and N-hydroxymethamphetamine.

甲基苯丙胺是通过多种途径从两种主要前体麻黄碱/伪麻黄碱或苯基-2-丙酮 (P2P) 生产的。多种合成路线会产生许多可能的杂质（副产物或中间体）。通过气相色谱-质谱 (GC-MS) 对甲基苯丙胺进行杂质分析是法医化学家和研究人员协助识别合成途径并将缉获量联系起来的重要工具。随着替代路线的出现，继续研究杂质谱非常重要。一种这样的替代途径是基于麻黄碱/伪麻黄碱的途径，使用通常与苯基-2-丙酮(P2P)途径相关的前体、苯甲醛和硝基乙烷。苯甲醛和硝基乙烷缩合形成2-硝基-1-苯基-1-丙醇。随后的还原产生相应的2-氨基-1-苯基-1-丙醇。用碳酸二甲酯环化甲基化生成3,4-二甲基-5-苯基-2-恶唑烷酮，然后催化氢解或碱性水解分别形成甲基苯丙胺和麻黄碱/伪麻黄碱。本文介绍了替代路线的杂质概况。发现中间体 2-硝基-1-苯基-1-丙醇还原为 2-氨基-1-苯基-1-丙醇的条件会影响甲基苯丙胺产品中观察到的副产物。值得注意的副产物是苯丙胺、N-乙基苯丙胺和N-羟基甲基苯丙胺。