title: Selectivity of gas-phase ion/molecule reaction of carbon dioxide with phenide ions.
abstract: On contrary to the widely accepted conviction that the m/z 93 ion derived from phenol does not react with CO2, we demonstrate that it makes an adduct with CO2 to a small but demonstrable extent. For example, the product-ion mass spectrum recorded for the m/z 98 ion derived from [(2)H6]phenol showed a small peak at m/z 142 when CO2 was used as the collision gas. The formation of an m/z 137 adduct ion from the m/z 93 ion (generated either directly from phenol, or indirectly from salicylic acid by in-source decarboxylation) was demonstrated also by multiple-reaction-monitoring tandem mass spectrometric experiments. According to literature, the m/z 93 ion derived from salicylic acid does not undergo CO2 addition because it is deemed to exist only in the phenoxide form. This reaction has been previously proposed as a method for differentiating phenoxide ion from its isomeric hydroxyphenide ions. We propose that the m/z 93 ion, albeit small, exists also as the phenide form together with the predominant phenoxide ion.
authors.affiliation: Center for Mass Spectrometry, Department of Chemistry, Chemical Biology, and Biomedical Engineering, Stevens Institute of Technology, Hoboken, NJ, 07030, USA.
authors.forename: Chongming
authors.initials: C
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Athula B
authors.initials: AB
authors.lastname: Attygalle
keywords: CO2 adducts; ion/molecule reaction; phenide anions; phenoxide anions; salicylate