Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)

O 60.105: Poster

Wednesday, March 16, 2011, 17:30–21:00, P4

In-situ alkylation reaction of two ionic liquids studied by X-ray photoelectron spectroscopy (XPS) — •Inga Niedermaier¹, Claudia Kolbeck¹, Florian Maier¹, Nicola Taccardi², Peter Wasserscheid², and Hans-Peter Steinrück¹ — ¹Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, 91058 Erlangen — ²Lehrstuhl für Chemische Reaktionstechnik, Egerlandstr. 3, 91058 Erlangen

Ionic liquids (ILs) - salts with a melting temperature below 100 ^∘C - have highly attracted attention due to their great potential in many fields, e.g. in catalysis or electrochemistry, and as a new class of tailored solvents. Due to their extremely low vapour pressure, ILs can be investigated with X-ray photoelectron spectroscopy (XPS) under ultra-high vacuum conditions allowing for in-situ studies of reactions in the near-surface region.

For the first time, an in-situ alkylation could be directly monitored by XPS in a 1:1 mixture of the two ILs [C₈C₁Im][Cl(CH₂)₃SO₃] (IL 1) and [(Me₂N(CH₂)₃)C₁Im][Tf₂N] (IL 2). In this thermally activated reaction, the amine group of the [(Me₂N(CH₂)₃)C₁Im]⁺ cation (2) reacts quantitatively with the [Cl(CH₂)₃SO₃]⁻ anion (1), producing an ammonium group in a new cation and a free chloride anion. Cl 2p spectra directly reflect the transformation of the covalently bound chlorine of (1) into the chloride anion. Additionally, angle resolved XPS (ARXPS) provides information on surface enrichment and orientation effects of the pure ILs and in the binary mixture before and after alkylation. - This work was supported by the DFG through SPP 1191 and the Cluster of Excellence ’Engineering of Advanced Materials’.