Generation of gas‐phase sodiated arenes such as [(Na₃(C₆H₄)⁺] from benzene dicarboxylate salts

Abstract

Abstract Upon collision‐induced activation, gaseous sodium adducts generated by electrospray ionization of disodium salts of 1,2‐ 1,3‐, and 1,4‐benzene dicarboxylic acids ( m / z 233) undergo an unprecedented expulsion of CO 2 by a rearrangement process to produce an ion of m / z 189 in which all three sodium atoms are retained. When isolated in a collision cell of a tandem‐in‐space mass spectrometer, and subjected to collision‐induced dissociation (CID), only the m / z 189 ions derived from the meta and para isomers underwent a further CO 2 loss to produce a peak at m / z 145 for a sodiated arene of formula (Na 3 C 6 H 4 ) + . This previously unreported m / z 145 ion, which is useful to differentiate meta and para benzene dicarboxylates from their ortho isomer, is in fact the sodium adduct of phenelenedisodium. Moreover, the m / z 189 ion from all three isomers readily expelled a sodium radical to produce a peak at m / z 166 for a radical cation [( • C 6 H 4 CO 2 Na 2 ) + ], which then eliminated CO 2 to produce a peak at m / z 122 for the distonic cation ( • C 6 H 4 Na 2 ) + . Copyright © 2009 John Wiley & Sons, Ltd.