Hannover 2013 – scientific programme

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MO: Fachverband Molekülphysik

MO 12: Femtosecond Spectroscopy III

MO 12.3: Talk

Tuesday, March 19, 2013, 14:45–15:00, F 102

Ultrafast photofragment ion spectroscopy of the Wolff rearrangement in 5-diazo Meldrum’s acid in the gas phase — Andreas Steinbacher, •Sebastian Roeding, Tobias Brixner, and Patrick Nuernberger — Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg

We investigate the multisequential photochemistry of 5-diazo Meldrum’s acid (DMA), a photoactive compound used in lithography, by femtosecond photofragment ion spectroscopy in the gas phase. Former studies [1,2] in solution revealed an ultrafast intramolecular Wolff rearrangement to a ketene after UV excitation, followed by subsequent reactions with a solvent molecule. In this gas phase study, the absence of interactions and reactions with solvent molecules allows us to focus on the photochemistry of the ketene intermediate. Besides direct fragmentation of this intermediate to acetone and carbon monoxide, we further find experimental indications that a second Wolff rearrangement occurs, as was conjectured earlier for this molecule [3] from photofragment analysis.
P. Rudolf, J. Buback, J. Aulbach, P. Nuernberger, and T. Brixner, JACS 2010, 132, 15213-15222
G. Burdzinski, J. Réhault, J. Wang, and M. S. Platz, J. Phys. Chem. A 2008, 112, 10108-10112
S. L. Kammula, H. L. Tracer, P. B. Shevlin, and M. Jones, J. Org. Chem. 1977, 42, 2931