Die thermische Fragmentierung einiger Naphthalin-Derivate wird durch Pyrolyse-Massenspektrometrie untersucht. Monosubstituierte Jod-und Nitro-naphthaline liefern vorwiegend Naphthyl-Radikale, wahrend 1.2-, 2.3-, 1.8-und 1.
Mass Spectrometry of Unstable Organic Molecules, V *). Evidence for Isomeric Dehydronaphthalenes from Pyrolysis Mass SpectrometryThe thermal fragmentation of some naphthalene derivatives is investigated by pyrolysis mass spectrometry. Monosubstituted iodo-and nitro-naphthalenes decompose to naphthyl radicals, but 1,2-, 2,3-, 1,8-and 1,5-disubstituted derivatives (iodides, bromides, dicarboxylic acid anhydrides and acenaphthenequinone) yield mainly dehydronaphthalenes. Similarly 1,5-dinitronaphthalene (16) decomposes to 1,5-dehydronaphthalene (4), while other products are formed by pyrolysis of the 1,2-and 1,8-derivatives 15 and 17 due to an ortho-or perieffect, respectively. The generation of dehydronaphthalene oxide (26) in the pyrolysis of 1,2-dinilro naphthalene (15) is assumed. -The ionization potentials of 1,2-, 2,3-, 1,8-and 1,5-dehydronaphthalene (1 -4) are 8, 61, 8,66, 7,93, and 8,18 eV, respectively. Stabilization energies are calculated which result in the following order of stability for the isomeric dehydronaphthalenes: 2 >4 >1 >3.Von den 10 verschiedenen Dehydronaphthalinen (DHN) sind bisher in der Gasphase 2.3-1) und 1.8-1)DHN (2 bzw. 3), in kondensierter Phase 1.2-21, 2.3-2) und