Carboxylation Enhances Fragmentation of Furan upon Resonant Electron Attachment

Abstract

We report a dissociative electron attachment study to 2-furoic acid (C 5 H 4 O 3 ) isolated in a gas phase, which is a model molecule consisting of a carboxylic group and a furan ring. Dissociation of furan by low energy electrons is accessible only via electronic excited Feshbach resonances at energies of incident electrons above 5 eV. On the other hand, carboxylic acids are well-known to dissociate via attachment of electrons at subexcitation energies. Here we elucidate how the electron and proton transfer reactions induced by carboxylation influence stability of the furan ring. Overlap of the furan and carboxyl π orbitals results in transformation of the nondissociative π 2 resonance of the furan ring to a dissociative resonance. The interpretation of hydrogen transfer reactions is supported by experimental studies of 3-methyl-2-furoic and 5-methyl-2-furoic acids (C 6 H 6 O 3 ) and density functional theory (DFT) calculations.

Metabolic Profile of Agropyron repens (L.) P. Beauv. Rhizome Herbal Tea by HPLC-PDA-ESI-MS/MS Analysis

“…Among the ESI- signals at low mass values, eight small organic acids were suggested by the ESI- signals at m / z 87, 89, 97, 111, 115, 133, 173 and 191, likely corresponding to the deprotonated forms [M-H] − of pyruvic, lactic, phosphoric, 2-furoic, fumaric, malic, cis -aconitic and citric acids, respectively ( Figure 1 a). The assignments were supported by the absence of the corresponding [M+H] + or adducts in ESI+ ( Figure 1 b), and by fragmentation spectra obtained in daughter scans by selecting the precursor ion [M-H] − , besides a good agreement with the literature [ 52 , 53 , 54 , 55 , 56 ]. Data are shown in Table 3 .…”

Electron Energy Loss Processes in Methyl Methacrylate: Excitation and Bond Breaking

“…The dominant DEA band at 8.5 eV has to originate from a core-excited resonance, but we are not able to determine its configuration. A rich fragmentation pattern of such resonances is indeed expected. , …”

“…A rich fragmentation pattern of such resonances is indeed expected. 57,58 The parent ion was not observed in the gas-phase experiment. This is not unusual, as DEA and autodetachment typically occur on a shorter time scale than the detection.…”

Interaction of low-energy electrons with radiosensitizers

“…Single occupied molecular orbital SOMO, forms upon electron attachment into the lowest unoccupied orbital (LUMO) of the neutral precursor molecule. The effects of the substituents can be expected for attachment at higher energies due to the often observed additive effect of electron attachment 184,185.…”