The elimination of small neutral molecules and fragments in mass spectra—II: 2‐substituted 8‐hydroxyquinolines

The mass spectra of a series of 2‐substituted 8‐hydroxyquinolines and related compounds are reported. Fragmentation pathways based upon interpretation of spectra and metastable transitions for 8‐quinolinol; 2‐methyl‐8‐quinolinol; 4‐methyl‐8quinolinol; 2‐hydroxymethyl‐8‐quinolinol; 2‐aminomethyl‐8‐quinolinol; 8‐quinolinol‐2‐carboxaldehyde; 8‐quinolinol‐2‐carb‐oxaldehyde oxime; and 8‐quinolinol‐2‐carboxaldehyde tert‐butylimine are discussed, as are dissociations in the related compounds 2‐hydroxymethyl quinoline and quinoline‐2‐carboxaldehyde oxime. It is suggested that the molecular ions of 2‐substituted‐8‐quinolinols undergo rearrangement to a substituted azatropylium ion prior to dissociation. An ion of m/e 89 has been observed in these spectra and is considered to be characteristic of the quinoline nucleus bearing an X‐substituent in any position, where X OR, SR, NH 2 etc. (R H, CH 3 , etc).