GC-MS Studies on Methoxymethylene- Substituted Phenethylamines Related to MDA, MDMA, MDEA and MDMMA

Abstract

This thesis mainly focused on synthesis and analysis approaches of eight methoxymethylene phenethylamine compounds associated with MDMA and MBDB series structures. Gas chromatography- mass spectrometry (GC-MS) methods were used to separate the target compounds and important intermediates with their homologues or regioisomeric compounds. Gas chromatography- time of flight detector (GC-TOF) was used for the exact mass analysis of characteristic MS fragments. Unlike the ethoxy phenethylamines, the studied methoxymethylene phenethylamines have a unique fragment of m/z 104 under EI mass spectrometry. Possible mechanism for this m/z 104 fragment is proposed and supportive analytical studies were carried out in this thesis. The eight target compounds are divided into two groups: 4-methoxymethylene amphetamine series and 4-methoxymethylene butanamine series. Underivatized compounds in each group were nicely separated by GC. Heptafluorobutyramide derivatives of 6 derivatizable target compounds were synthesized, and the mass spectrum of the each derivatized compound reveals unique structural information for identification purposes. Previous studies have revealed the structure-activity relationships and separation approaches for direct, indirect regioisomerics and some isobarics related to MDMA. Especially, the most recent study of MDMA related compounds reveals a unique fragment m/z 107 generated by EI MS of ethoxy ring substituted phenethylamines. The proposed mechanism for the generation of the m/z 107 involves the engagement of ethoxy oxygen, and we are interested to find out what will happen to this characteristic m/z 107 fragment if the ester oxygen is moved one carbon away toward the side chain end. Thus, is seems necessary to initiate a study of the methoxymethylene phenethylamine series of compounds in order to be compared with the ethoxy phenethylamine homologues, and to further complete the separation study of MDMA with its regioisomeric and isobaric compounds.