GC–MS analysis of regioisomeric substituted N-benzyl-4-bromo-2,5-dimethoxyphenethylamines

Structure fragmentation studies of ring‐substituted N‐trifluoroacetyl‐N‐benzylphenethylamines related to the NBOMe drugs

“…For each of these four series of phenethyl aromatic ring‐substitution patterns, all six regioisomeric dimethoxybenzyl‐substituted analogues (2,3‐, 2,4‐, 2,5‐, 2,6‐, 3,4‐ and 3,5‐dimethoxy) were prepared, derivatized and analyzed via GC/MS. These compounds were synthesized by reductive alkylation reactions with 2,5‐dimethoxy‐, 2‐methoxy, 3‐methoxy‐ or unsubstituted phenethylamines and the corresponding six regioisomeric dimethoxybenzaldehydes as described in previous reports . The EI‐MS spectra of the TFA derivatives of each of the 2,5‐DMPEADMB, 2‐MMPEADMB, 3‐MMPEADMB and PEADMB series are shown in Figures and the relative abundances of fragment ions are summarized in Table .…”

“…While the m / z 151 cation could occur via several fragmentation pathways, the substituted phenylethene radical cation and the m / z 263 ion appear to occur from the distonic molecular radical cation. Previous studies have shown that the relative intensities of these three major fragments can be used to determine the dimethoxy group substitution pattern on the aromatic ring of the N ‐benzyl group for TFA‐25X‐NBOMe compounds. However, all these observations were made for molecules in which the phenethylamine portion of the NBOMe structure contained the electron‐rich 4‐halogen and 2,5‐dimethoxyphenyl groups.…”

“…Based on the commercial availability of precursor aldehydes, the synthesis and analytical evaluation of the six regioisomeric N ‐dimethoxybenzyl NBOMe derivatives were recently described for the 4‐bromo‐2,5‐dimethoxyphenethylamine series . The six isomers in each series displayed very little analytical uniqueness and the major EI‐MS fragment ions were essentially equivalent for each isomer.…”

“…The acylation of the secondary amine nitrogen in the 4‐iodo‐ and 4‐bromo‐ N ‐dimethoxybenzyl‐2,5‐dimethoxyphenethylamines with trifluoroacetyl groups allowed differentiation of the six isomers based on some unique fragment ions and the relative abundance of other common ions . The purpose of the study reported here was to determine the role of the electron‐donating groups (halogen and dimethoxy) in the pathway of decomposition (Figure ) for the distonic molecular radical cation formed by hydrogen radical transfer from the phenethyl side‐chain to the carbonyl of the TFA group.…”

Gas Chromatography—Fourier Transform Infrared Spectroscopy for Unambiguous Determination of Illicit Drugs: A Proof of Concept

“…Relying on distinct chemical properties, IR may well complement the information afforded by mass spectrometry (MS), in achieving structural identification of volatile and semi-volatile molecules. Moreover, by measuring small energy differences based on rotational and vibrational amplitudes between individual molecular bonds, FTIR spectroscopy enables to overcome one limitation of MS detection, in discriminating regioisomeric compounds (Kempfert, 1988 ; Almalki et al, 2019 ).…”