Seminars in Organic Synthesis

Prof. Gabriele Renzi focuses his job on the modern application of radiolysis as a tool for generating specific ions in the gas phase and for investigating their behavior towards neutral substrates. Radiation-chemistry investigation on gas-phase ion-molecule reactions integrates and completes the kinetic and mechanistic information obtained by mass spectrometric methodologies. The greatest contribution of radiation chemistry to gas-phase ion-molecule reactions research concerns: (i)- the study of their kinetics and mechanism under conditions not limited to the rather narrow density range covered by conventional mass spectrometry; (ii)- the fast interception and neutralization of the relevant ionic intermediates, which strongly reduce their isomerization and fragmentation generally observed in mass spectrometry within the long time interval between the ion generation and detection; (iii)- the characterization of the ion-molecule intermediates through the structural and stereochemical analysis of their neutral products, which normally represents an inherent limitation of purely mass spectrometric methods. As in the source of mass spectrometers, radiolytic ions are generated from the interaction of energetic electrons with suitable neutral gases, contained in glassy bulbs at pressures from a few torr to several atmospheres. Under such conditions, the radiolytic ions may undergo efficient thermal equilibration by collisions with the bath gas prior to their conversion to products. The reactivity of the thermalized ions is measured by standard kinetic procedures, including pressure- and temperature-dependence studies, isotopic labelling and competition experiments. The integrated approach to gas-phase ion chemistry based on the coordinated application of mass spectrometric and radiolytic techniques has successfully been applied to problems related to the existence, the structure, and the stability of gaseous cations and has provided new mechanistic insight into many classe