Collision‐induced dissociation processes of protonated benzoic acid and related compounds: competitive generation of protonated carbon dioxide or protonated benzene

Upon activation in the gas phase, protonated benzoic acid ( m/z 123) undergoes fragmentation by several mechanisms. In addition to the predictable water loss followed by a CO loss, the m/z 123 ion more intriguingly eliminates a molecule of benzene to generate protonated carbon dioxide ( H ‐ O + ═ C ≡ O , m/z 45), or a molecule of carbon dioxide to yield protonated benzene ( m/z 79). Experimental evidence shows that the incipient proton ambulates...