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GC-MS and GC-IR analysis of substituted N-benzyl 4-bromo-2,5-dimethoxyphenylisopropylamines

NCJ Number
Forensic Chemistry Volume: 24 Dated: June 2021
Younis Abiedalla; Ahmad J. Almalki; Jack DeRuiter; C. Randall Clark
Date Published
June 2021

This study examined the analytical properties of nine phenylisopropylamines.



The N-(methoxybenzyl- and dimethoxybenzyl)-4-bromo-2,5-dimethoxyphenylisopropylamines are a likely category of novel psychoactive substances based on a combination of structural features for the amphetamine and the NBOMe drugs. The nine compounds in the current study were synthesized from readily available precursor materials via a common synthetic pathway. The gas chromatographic separations of the monomethoxybenzyl- and dimethoxybenzyl subseries of regioisomers were achieved on a midpolarity capillary column and the elution order appears related to aromatic ring substituent crowding. The significant ions in the EI-MS spectra consist of the iminium cation and other fragments originating from the nonbrominated benzylamine portion of the molecules. These observations are consistent with those of the traditional unbranched phenethyl NBOMe analogues. The mass of the major fragments varies based on the number of methoxy groups of the benzyl aromatic ring. Within each subseries of monomethoxy and dimethoxy analogues, the mass spectra are remarkably similar with slight variations in relative abundance in most cases. Minor ions containing bromine occur for the 4-bromo-2,5-dimethoxybenzyl cation and its product ion resulting from the rearrangement loss of the 2-methoxy group in the form of formaldehyde. The vapor phase infrared spectra generated in GC–IR experiments provide data for the determination of the position of substitution of the methoxy groups on the benzyl aromatic ring in both the monomethoxy- and dimethoxybenzyl subseries. (publisher abstract modified)