Essen, Univ., Diss., 2001. / Computerdatei im Fernzugriff.

Essen, Univ., Diss., 2001. / Computerdatei im Fernzugriff.

Universiẗat, Diss., 2001--Essen.

<p> 2-Tetrazens are often used as high energy-density materials. Only a few synthetic methods  exist for making them. Further, their structure-property relationships remain largely unexplored.  Asphaltenes are usually a complex mixture found in the heaviest fraction of heavy crude oil. Their structural characterization and understanding have become a pertinent task for petroleum industry  around the world. Mass spectrometry is a powerful analytical tool for the detection and  characterization of unknown compounds even in complex mixtures. It features high sensitivity and  speed and can provide a variety of valuable information for different types of analytes. This thesis  focuses on the development of an effective synthetic method for 2-tetrazenes and the mass  spectrometry study of the ionized 2-tetrazenes. In addition, the mass spectrometric behavior of  ionized asphaltene model compounds are also discussed in this thesis. Chapter 2 describes the instrumentation and fundamental aspects of the mass spectrometers used in the research discussed in this thesis. Chapter3 introduces an effective synthetic method for  2-tetrazens based on iodine-mediated oxidative N-N coupling reaction of hydrazines. Chapter 4  presents the fragmentation behavior of ionized 2-tetrazenes in tandem mass spectrometry experiments. Upon collision-activated dissociation (CAD), ionized alkyl-substituted linear 2- tetrazenes underwent simpler fragmentation reactions than the ionized aromatic 2-tetrazenes or a  cyclic 2-tetrazene. The observations were rationalized by using quantum chemical calculations.  Chapter 5 presents the fragmentation behavior of ionized asphaltene model compounds under  medium-energy collision-activated dissociation (MCAD). The comparison between the different  behaviors of the molecular radical cations of these compounds provided useful information for the  identification of related unknown compound </p>