The Loss of a hydroxyl group from the molecular ions of alkylnitrobenzenes

It is confirmed that the loss of HO˙ from the molecular ion of o‐nitrotoluene involves exclusively a hydrogen from the methyl group. However, in higher homologues hydrogen atoms from non‐benzylic sites are also implicated. With such compounds this fragmentation mode is shown not only by the ortho but, to a lesser extent, by the meta and para isomers as well. The proportion of the total ion current borne by the [M – 17]+ ion follows the order ortho > meta > para, which is attributed to substituent migration around the ring with a hydroxyl radical only being lost when the groups are on adjacent ring atoms. Other ions present in the spectra point to interaction between substituents to form a new heterocyclic ring.