Structure identification and analysis of the suspected chemical precursor of 2-fluorodeschloroketamine and its decomposition products.
Drug testing and analysis – June 01, 2022
Source: PubMed
Summary
The precursor to the illicit drug 2-FDCK, 2-fluorodeschlorohydroxylimine, breaks down into two distinct α-hydroxyl ketones. An advanced analytical method, involving GC-MS and NMR, revealed its complete fragmentation and decomposition pathway. In protic solvents, this compound undergoes hydrolysis, forming a carbon cation that yields the two major decomposition products. Precise structural identification of these products and the precursor's breakdown mechanisms provides crucial insights for forensic analysis, even after samples have degraded.
Abstract
In this work, 1-[(2″-fluorophenyl)(methylimino)methyl]cyclopentan-1-ol (2-fluorodeschlorohydroxylimine) was identified as a suspected chemical precursor of 2-fluorodeschloroketamine (2-FDCK) using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-quadrupole/time-of-flight mass spectrometry (GC-Q/TOF-MS) and comparing the data with those of ketamine and its chemical precursor, hydroxylimine. Furthermore, the entire fragmentation pathway of 2-fluorodeschlorohydroxylimine was theorized from the GC-MS spectrum recorded using an electron ionization (EI) source, and the mechanisms and decomposition pathways of 2-fluorodeschlorohydroxylimine were elucidated. In protic solvents, the nitrogen atom in the C═N group of 2-fluorodeschlorohydroxylimine underwent a protonation reaction. Thereafter, the traces of water present in protic solvents promoted the hydrolysis of the protonated imine, and a carbon cation was obtained following the loss of methylamine. The carbon cation could follow the classical decomposition mechanism of imines and yield an α-hydroxyl ketone, which was the major decomposition product, (2'-fluorophenyl)(1″-hydroxycyclopentyl)methanone. The cation could also undergo a loop expansion rearrangement and yield another α-hydroxyl ketone, 2-(2'-fluorophenyl)-2-hydroxycyclohexan-1-one. The structures of the two aforementioned decomposition products were elucidated using several techniques including theoretical calculation, GC-MS, nuclear magnetic resonance (NMR), the prediction and assistance elucidation functions of ACDLabs-Structure Elucidator Suite, and the virtual separation technology of diffusion-ordered spectroscopy. The aforementioned study revealed important information about the chemical precursor of 2-FDCK and its decomposition. Furthermore, a set of methods for the qualitative analysis of 2-fluorodeschlorohydroxylimine were established, which facilitated accurate analysis of 2-fluorodeschlorohydroxylimine samples following decomposition or destruction.