STUDIES IN ORGANIC MASS-SPECTROMETRY .9. MASS-SPECTRA OF 9,10-DISUBSTITUTED 2,3,6,7-TETRAALKOXY-9,10-DIHYDROANTHRACENES - A REMARKABLE LOSS OF RADICALS FROM EVEN-ELECTRON IONS

The electron impact-induced fragmentations of 23 9,10-disubstituted 2,3,6,7-tetraalkoxy-9,10-dihydroanthracenes, including six stereoisomeric pairs, were studied. The loss of the 9-(or 10-)substituent constitutes the main fragmentation route. The resulting ions give rise to a remarkable violation of the so-called 'even-electron rule' as they eject the second substituent at the 10-(or 9-)position as a radical. The latter aspect was particularly investigated with the aid of low-energy (nominal value 15 eV) and mass-analysed ion kinetic energy spectra.