On the electron impact induced hydroxyl loss from o-nitrostyrene

Unimolecular hydroxyl (OD^˙) loss from regio- and stereo-specifically labelled o-nitrostyrenes 1a, 1c and 1d results in the formation of an ion which upon collisional activation gives identical mass spectra. Suggestions are made which aim at explaining: (i) the loss of stereochemical integrity of the diastereotopic methylene hydrogens in the course of hydroxyl elimination; and (ii) to account for the collision induced losses of CO and HNC from the [M—hydroxyl]⁺ ion.     

Homotopie-Operationen relativer Homotopiegruppen I

Ohne Zusammenfassung     

Zur massenspektrometrischen Eliminierung von Neutralpartikeln aus Molekel- und Fragment-Ionen

The possibility of elimination reactions without participation of the positive charge and/or electron deficient centers, in particular the loss of RCOOH, was investigated for molecular and fragment ions. Such processes, which could be referred to as quasithermal or quasi-photochemical reactions, were found to be absent or insignificant.     

Solvent effects on absorption and fluorescence spectra of diphenyltriafulvenes. Three modes of dipole moment variation upon excitation

Three representative diphenyltriafulvenes, 4,4′-dicyano-1,2-diphenyltriafulvene (I), hexaphenyltriapentafulvalene (II) and 10-(2,3-diphenylcyclopropenyliden)-anthrone (III) have been investigated. On excitation, the dipole moment of I decreases and reverses sign, i.e., from a value of 7.9 D in the ground state to a value of about ?5.3 D in the first excited electronic state. That of II remains unchanged at 6.3 D, and that of III increases from 8.5 D to about 26 D. The Onsager radius of 1 was found to be about 8.7 Å and that of IIi, about 12 Å.