Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 11: New Instruments and Methods
CPP 11.8: Vortrag
Dienstag, 27. März 2012, 11:45–12:00, C 243
Organic reactions at ionic liquid surfaces studied by in-situ XPS — •Inga Niedermaier1, Claudia Kolbeck1, Nicola Taccardi2, Peter Schulz2, Peter Wasserscheid2, Hans-Peter Steinrück1, and Florian Maier1 — 1Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen — 2Lehrstuhl für Chemische Reaktionstechnik, Egerlandstr. 3, 91058 Erlangen
Due to their low vapour pressure, ionic liquids - organic salts with a melting point below 100 °C - can be investigated by surface science techniques under UHV conditions. In particular, angle-resolved X-ray photoelectron spectroscopy (ARXPS) has been proven to be an effective tool for studying molecular enrichment and orientation effects even for the topmost surface layers of the ionic liquid. Here, we demonstrate that ARXPS also allows accessing classical organic chemical reactions normally carried out in common solvents, by employing reactive centres covalently fixed to cations or anions of ILs. This novel concept is successfully carried out for a nucleophilic substitution where a tertiary amine attached to an imidazolium cation is alkylated by the chloroalkyl moiety of the anion. In course of the reaction, covalently bound chlorine (neutral) is converted to chloride (negatively charged) and amine (neutral) to ammonium (positively charged). These changes are reflected by characteristic shifts in the N 1s and Cl 2p ARXP spectra. In this respect, in-situ ARXPS represents a novel tool to analyse reaction pathways at liquid surfaces on a molecular level. - Supported by the DFG through SPP 1191 and by the Cluster of Excellence - Engineering of Advanced Materials.