Die Massenspektren einiger Arsen- und Arsenigsäureester – Kinetische Untersuchung ihres Fragmentierungsverhaltens

Mass Spectra of some Arsenic and Arsenious Esters. Kinetic Study of their Fragmentation Reactions The mass spectra of some arsenic and arsenious esters are reported. Based on a mechanistic interpretation of the kinetic of competitive and consecutive reactions correlations between mass spectra and molecular structure have been found. Conclusions: (a) molecular ions are not or very small observable; (b) fragment ions with trivalent and fivevalent arsenic (e.g. As(OCH₃)) are very abundant; (c) the first fragmentation reaction of the molecular ion is usually a simple cleavage, the second is elimination of a neutral by a rearrangement; (d) rearrangement reactions exhibit less activation energies and less frequency factors than simple cleavages, this is the reason for the differences between 70 eV and 9 eV spectra; (e) C? C cleavage in the ethoxy compounds is favoured because of the formation of mesomeric onium ions; (f) some fragmentations by electron impact are analogous to pyrolytic decompositions; (g) in the fragment ions of OAs(OCH₂C₆H₅)₃ the charge is placed on the aromatic ring.