Premium
Microwave‐Assisted Partial Hydrogenation of Citral by using Ionic Liquid‐Coated Porous Glass Catalysts
Author(s) -
Gallert Thomas,
Hahn Martin,
Sellin Martin,
Schmöger Christine,
Stolle Achim,
Ondruschka Bernd,
Keller Thomas F.,
Jandt Klaus D.
Publication year - 2011
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201100154
Subject(s) - ionic liquid , citral , dicyanamide , catalysis , citronellal , x ray photoelectron spectroscopy , chemistry , hydrosilylation , inorganic chemistry , tetrafluoroborate , chemical engineering , organic chemistry , materials science , chromatography , essential oil , engineering
The microwave‐assisted hydrogenation of citral (3,7‐dimethylocta‐2,6‐dienal) to citronellal with molecular hydrogen as the reducing agent was investigated. Several polar and non‐polar solvents were screened and imidazolium‐based ionic liquids were applied as modifiers for the palladium‐containing porous glass catalysts (Pd/TP). The best results were obtained with N ‐ethyl‐ N’ ‐methylimidazolium dicyanamide, N ‐ethyl‐ N’ ‐methylimidazolium acetate, or N ‐ethyl‐ N’ ‐methylimidazolium trifluoroacetate, which were used to prepare supported catalysts with an ionic liquid layer (SCILL) on Pd/TP by wet‐impregnation. The influence of pressure and temperature when using these ionic liquid‐containing catalysts, as well as their long‐term stabilities, were examined. Working with microwave‐assisted heating, high yields of citronellal were achieved under mild conditions within short reaction times. Catalyst characterization was carried out by means of BET measurements, X‐ray photoelectron spectroscopy (XPS) and thermo‐gravimetric analyses. The influences of the ionic liquid layer were derived from experiments carried out before and after the reactions.