The elimination of small neutral molecules and fragments in mass spectra—I. Substituted salicylic acids and their derivatives

The mass spectra of various ring-substituted salicylic acids and derivatives thereof have been examined. Fragmentation pathways for derivatives of salicylic acid; 3-NO₂ salicylic acid; 5-I salicylic acid; 3-NO₂, 5-I salicylic acid; and 3-NH₂, 5-I salicylic acid are suggested. The major dissociations of these compounds are by elimination of the elements of neutral molecules, e.g. water, methanol, ketene (from the acetylated compounds) carbon monoxide, nitric oxide and nitrogen dioxide, leading to (iodo) phenoxy and (iodo) quinone type ion structures. These ions further decompose to yield the corresponding substituted cyclopentadienyl and cyclopropylium ions.