Continuous flow hydrosilylation in SILP/scCO2 systems - an innovative approach to reduction and functionalization of alkynes, imines and carbonyl compounds

• Applicants: Dr. Giancarlo Franciò; Professor Dr. Walter Leitner
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426583288

The goal of the project is to design, evaluate, and demonstrate methods for continuous-flow catalytic hydrosilylation of molecules bearing C≡C, C=O and C=N bonds. For this purpose, catalytic systems comprising molecular catalysts or catalytically active nanoparticles stabilized and immobilized in a supported ionic liquid phase (SILP) or on Phosphotungstic Acid (PTA)/aluminum oxide (Alox) supports will be developed. Stereoselective versions are envisaged too by using molecular catalysts with chiral ligands. In the SILP-scCO2 approach, supercritical carbon dioxide (scCO2) will be used as a mobile phase to transport substrates into the catalyst containing SILP matrix and simultaneously extract the products for isolation. This methodology takes advantagefrom the gas-like transport and liquid-like solubility properties of scCO2. Thanks to the high solubility of organosilicon compounds in compressed carbon dioxide and the negligible solubility of the SILP materials in the same medium, this approach is particularly suited for the envisaged application. In the case of the (PTA)/Alox approach, the use of neat reagents, scCO2 or conventional solvents will be used to realize the flow depending on the nature of the substrates/products. This study will provide fundamental knowledge on the combination ofcatalysis with advanced fluids, thus contributing to a general progress in the understanding,control, and mastering of continuous-flow processes at the three different, yet stronglyinterconnected, process levels:- Molecular scale: How do the molecular interactions of catalytically active metal complexes and clusters with the immobilization matrix affect their performance on the short and on the long term?- Mesoscale: How do the physico-chemical properties of the catalyst, subtrates andproducts harmonize with the stationary and mobile phase and, in general, with the devised strategy for integrating reaction and separation?- Macroscale: How should a compact continuous-flow setup be designed and constructed to implement the devised reaction/separation approach and to allow both reaction and catalyst monitoring?The exploitation of these three levels with a focus on mutual compatibility will result in a new sustainable approach for catalytic organosilicon chemistry leading to high productivities and improved or even novel selectivities. The combination of flow-chemistry using scCO2 as benign transport medium with an effective catalyst immobilization procedure will ensure metal-free and solvent-free product isolation, thus cutting down any additional tedious or material intensive workup procedures. We aim at a flexible methodology enabling the continuous flow hydrosilylation of various alkynes and carbonyl compounds with minor operational adjustments.

• DFG Programme: Research Grants
• International Connection: Poland
• Partner Organisation: Narodowe Centrum Nauki (NCN)
• Cooperation Partner: Professor Dr. Jedrzej Walkowiak