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Keywords:

Science & Technology, Physical Sciences, Technology, Physics, Atomic, Molecular & Chemical, Spectroscopy, Physics, dimethyl isophthalate, mass spectrometry, metastable ion, proton transport catalysis, PHTHALATE, TEREPHTHALATE, DISSOCIATION, MIGRATION, ION, 0301 Analytical Chemistry, 0305 Organic Chemistry, 0306 Physical Chemistry (incl. Structural), Analytical Chemistry, 3401 Analytical chemistry, 3406 Physical chemistry, 5102 Atomic, molecular and optical physics

Abstract:

The MS/MS spectrum of the metastable molecular ions of dimethyl isophthalate 1 differs from that of the isomeric dimethyl terephthalate 2 by the observation of, inter alia, a quite intense loss of C,H2,O ascribed to formaldehyde. Results obtained using a combination of mass spectrometry techniques suggest that this process could consist of an isomerization reaction of the molecular ion into an ion-neutral complex (INC) linking a benzoyl radical and neutral formaldehyde to a proton [Ar{single bond}C{double bond, long}O⋯H⋯O{double bond, long}CH2]{radical dot}+. Within the complex, a proton transfer catalyzed by formaldehyde occurs resulting in the production of an ionized cyclohexadienylidene methanone (ketene) structure. © 2008 Elsevier B.V. All rights reserved.