Massenspektrometrische Untersuchungen an Heterocyclen—IV: Zur Wasserstoffabspaltung aus Xanthen und Thioxanthen

The structure of the [M — 1] ions of thioxanthene (I) and xanthene (II) is investigated by means of the 9,9-dideuteroderivatives (Ia and Ia). The formation of an [M — 1]ion from Ia and IIa shows that beside a simple dissociation reaction a rearrangement to a tropylium ion is involved. A further rearrangements of this type occurs in the frgmentation of thioxanthene-S,S-dioxide (III).