FRAGMENTATION OF 1-ALKYL DERIVATIVES OF 5-NITRO-2,1-BENZISOTHIAZOLINEAND 7-NITRO-2,1-BENZISOTHIAZOLINE 2,2-DIOXIDES UPON ELECTRON IONIZATION

Fragmentation patterns upon electron ionization of some 1-alkyl-5-nitr o- and 1-alkyl-7-nitro-2,1-benzisothiazoline 2,2-dioxides are describe d. It is observed that the molecular ions of the 7-nitro isomers under go rearrangement reactions resulting in the loss of a molecule of the appropriate carbonyl compound and, concurrently, an acyl radical. Mech anisms for these reactions, which can be assumed to be an example of t he ''ortho-effect'', are proposed.