Palladium-Containing Ionic Liquid-Based Ordered Mesoporous Organosilica: An Efficient and Reusable Catalyst for the Heck Reaction

The catalytic application of a novel palladium-containing periodic mesoporous organosilica with ionic liquid framework (Pd@ PMO-IL-I) in the Heck cross-coupling reaction was described. This nanocatalyst was first synthesised and characterised by using diffuse reflectance infrared Fourier transform spectroscopy, thermogravimetric analysis, transmission electron microscopy and nitrogen sorption analysis. The efficiency of the Pd@ PMO-IL-I catalyst was investigated in the Heck cross-coupling of various aryl halides with alkyl acrylates in the presence of N-methylpyrolidone at 140 degrees C. The catalyst demonstrated excellent catalytic activity with various aryl iodides, aryl bromides, and activated aryl chlorides, which gave the corresponding coupling products in good to excellent yields and with excellent E-selectivities. Moreover, the recoverability, reusability and the actual nature of the Pd@ PMO-IL-I catalyst were investigated to show the effect of ionic liquid moieties on the stabilisation of palladium species during the reaction. Our study showed that the catalyst could be recovered and reused at least nine times without any appreciable decrease in activity and selectivity, which confirmed its high efficiency and high stability under the reaction conditions and during recycling stages.