Ortho effects in organic molecules on electron-impact I—Oxidation of olefinic double bond by the ortho nitro group in stilbazoles

The electron-impact-induced fragmentation in 2′-nitro-4-stilbazole is triggered by the oxidation of the olefinic double bond by the ortho nitro group in the initial step, while such an interaction under the same condition is totally absent in the meta and para isomers. The important fragmentation in 2′-nitro-2-stilbazole is the formation of a cyclised ion with the elimination of the nitro group.