Generation and Characterization of Distonic Dehydrophenoxide Radical Anions under Electrospray and Atmospheric Pressure Chemical Ionizations

Authors

Kiran Kumar Morishetti, University of the Pacific
Prabhakar Sripadi, Indian Institute of Chemical Technology
Vairamani Mariappanadar, Indian Institute of Chemical Technology
Jianhua Ren, University of the PacificFollow

Document Type

Article

Publication Title

International Journal of Mass Spectrometry

Department

Chemistry

ISSN

1387-3806

Volume

299

Issue

2--3

DOI

10.1016/j.ijms.2010.10.025

First Page

169

Last Page

177

Publication Date

1-1-2011

Abstract

We have explored the possibilities of generating radical anions under electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) conditions. By using different sets of ortho-, meta-, and para-isomers of nitrobenzoic acids, methylphenols, and nitrophenols, and m-, and p-isomers of hydroxybenzaldehydes and hydroxyacetophenones as the precursor molecules, we have successfully generated the isomeric distonic dehydrophenoxide radical anions (m/z 92) using the ESI process by applying relatively high capillary voltages, the in-source dissociation (ISD) condition. Under the same conditions, the o-hydroxybenzaldehyde and the o-hydroxyacetophenone yielded the even-electron dehydrophenoxide anion (m/z 93) due to the well-known ortho-effect. The distonic phenoxide radical anions at m/z 92 were also generated under APCI-ISD conditions by using m- and p-isomers of nitrobenzaldehydes and nitroacetophenones. While the o-nitrobenzaldehyde and the o-nitroacetophenone mainly yielded the phenoxide anion at m/z 93, due to the ortho-effect. The collision-induced dissociation (CID) experiments of all the anionic precursor molecules formed from either ESI or APCI produced comparable mass spectra as those observed in the ESI-ISD or the APCI-ISD experiments. The radical anions at m/z 92 reacted with CO₂ and O₂ to form the CO₂ adduct and the oxygen atom abstraction product, respectively, revealing the dual-character of the distonic radical anions, the phenide ion and the phenyl radical. Computational studies support the results of the ion-molecule reactions.

Recommended Citation

Morishetti, K. K., Sripadi, P., Mariappanadar, V., & Ren, J. (2011). Generation and Characterization of Distonic Dehydrophenoxide Radical Anions under Electrospray and Atmospheric Pressure Chemical Ionizations. International Journal of Mass Spectrometry, 299(2--3), 169–177. DOI: 10.1016/j.ijms.2010.10.025
https://scholarlycommons.pacific.edu/cop-facarticles/665