Fragmentation processes of 1,2‐diphenoxyethane and 2‐phenoxyethanol by electron impact

Abstract

The unimolecular fragmentation processes of 1,Zdiphenoxyethane (1) and 2-phenoxyethanol (2) upon electron impact were investigated by a combination of mass-analyzed ion kinetic energy (MIKE) spectrometry, deuterium-labelling, high resolution mass spectrometry, and kinetic energy release (KER) measurement. The MIKE spectrum and the KER measurement indicate that the predominant fragment ion at mlz 120 was generated from metastable 1+' ions via loss of a phenol molecule (C&I@, 7), and that it has the same structure as the molecular ion of 2,3-dihydrobenzofuran (C&@, 3). The metastable 2" ion eliminates C2H40 and C2H30 to produce product ions at m/z 94 (C&O+., 7") and 95 (C,@Hp+) with single and double hydrogen atom transfer, respctively . These reactions occur through some complex rearrangement reactions.Fragmentation processes of gaseous organic ions produced by electron impact have been studied extensively by a combination of mass-analyzed ion kinetic energy (MIKE) spectrometry, deuterium-labelling, and kinetic energy release (KER) measurement.' By using these techniques, we have investigated the fragmentations of some aliphatic diethers of ethylenegly~ol.~,~ In these compounds, aldehyde andlor alcohol molecules were eliminated with single hydrogen atom migration.Recently, the detailed fragmentation mechanisms of some aliphatic ethers of ethyleneglycol have been reported by Milliet et al. The fragmentation of ethyleneglycol itself has also been studied by several authors.5-' In order to rationalize these fragmentation processes, very complex rearrangement reactions have been p r~p o s e d .~-~ The reactivity and fragmentation of ethyleneglycol diethers and some a,o-dialkoxyalkanes have also been investigated by using an ion cyclotron resonance (ICR) cell9 and collision-induced dissociation (CID) spectra."To the authors' knowledge, however, little is known concerning the fragmentation of the aromatic ethers of ethylenegly~ol."-'~ In this paper we report the results of a MIKE spectometry/D-labellinglhigh resolution mass spectrometry/KER measurement study of the fragmentation pathways of 1 ,Zdiphenoxyethane (1) and 2-phenoxyethanol (2). These compounds are the simplest aromatic ethers of ethyleneglycol. EXPERIMENTALThe mass spectra and high resolution data were obtained with a Hitachi (Tokyo, Japan) M-80A doublefocusing mass spectrometer. The MIKE spectra were recorded on a Hitachi RMU-7M reversed geometry instrument. The KER values were calculated from the width at half-height of the metastable peak, after correction for the main beam.'"'' 1,2-Diphenoxyethane-l, 1 ,2,2-d4 (l-d4) and phenyl vinyl ether (4) were synthesized by the Williamson method." 2-Phenoxyethanol-1 ,l-d2 (2-d2) was obtained by reduction of methylphenoxy acetate with LiAlD4. 2-Phenoxyethanol-0-d, (2-d,) and 2-phenoxyethanol-1,1,O-d, (2-d,) were obtained by repeated treatment of the parent compounds (2 and 2-d,) with D 2 0 . The degree of labelling obtained was better than 94%. 1,2-Diphenoxyethane (l), 2,3-dihydrobenzofuran (3), styrene oxide (S), a...

Synergistic Catalysts of Lewis Acid and Brønsted Acid for Highly Efficient Preparation of Bisphenol Compounds

“…The intermediate can cleave to R–C-S and ·C 2 H 4 COOH . In addition, the peak at 338.3387 ascribed to C 21 H 15 OS (error = 0.08) was considered as the other reaction intermediate …”

“…28 In addition, the peak at 338.3387 ascribed to C 21 H 15 OS (error = 0.08) was considered as the other reaction intermediate. 29 Based on the previous study, 12,14 in situ FT-IR and MS analyses, ZnCl 2 serves as an activator for carbonyl groups of 9fluorenone in the preparation of BPEF. Additionally, the carboxyl group in 3-mercaptopropionic acid is used to protonate the carbonyl group, and the thiol group participates in nucleophilic reactions to generate intermediates, thereby initiating subsequent reactions.…”