Title
Protomers of benzocaine : solvent and permittivity dependence Protomers of benzocaine : solvent and permittivity dependence
Author
Faculty/Department
Faculty of Sciences. Chemistry
Publication type
article
Publication
Washington, D.C. ,
Subject
Chemistry
Source (journal)
Journal of the American Chemical Society. - Washington, D.C.
Volume/pages
137(2015) :12 , p. 4236-4242
ISSN
0002-7863
ISI
000352244800040
Carrier
E
Target language
English (eng)
Full text (Publishers DOI)
Affiliation
University of Antwerp
Abstract
The immediate environment of a molecule can have a profound influence on its properties. Benzocaine, the ethyl ester of para-aminobenzoic acid that finds an application as a local anesthetic, is found to adopt in its protonated form at least two populations of distinct structures in the gas phase, and their relative intensities strongly depend on the properties of the solvent used in the electrospray ionization process. Here, we combine IR-vibrational spectroscopy with ion mobilitymass spectrometry to yield gas-phase IR spectra of simultaneously m/z and drift-time-resolved species of benzocaine. The results allow for an unambiguous identification of two protomeric species: the N- and O-protonated forms. Density functional theory calculations link these structures to the most stable solution and gas-phase structures, respectively, with the electric properties of the surrounding medium being the main determinant for the preferred protonation site. The fact that the N-protonated form of benzocaine can be found in the gas phase is owed to kinetic trapping of the solution-phase structure during transfer into the experimental setup. These observations confirm earlier studies on similar molecules where N- and O-protonation have been suggested.
E-info
https://repository.uantwerpen.be/docman/iruaauth/49fcf3/d8f8b2649e3.pdf
Full text (open access)
https://repository.uantwerpen.be/docman/irua/83318b/9863.pdf
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