Adel Keraani

This study is aimed at developing an innovative concept for the preparation of an olefin metathesis catalytic membrane. This goal was achieved by grafting a Grubbs II precatalyst on a zirconia membrane generating a tailor-made Hoveyda–Grubbs precatalyst on the surface of an ultrafiltration inorganic membrane. The obtained membranes were characterized by different techniques evidencing the grafting. The catalytic activity was also evaluated in a model ring-closing metathesis reaction. According to our knowledge, this manuscript reports the first ever so sophisticated catalytic membrane based on an organometallic complex of ruthenium. The proof of concept was achieved, although the membrane grafting must be improved for better catalytic activity.

The cross‐metathesis of renewable fatty acid methyl esters with acrolein was investigated. The bifunctional formyl‐esters obtained are interesting compounds for further transformations into bifunctional polymer precursors. Several experimental parameters and ruthenium catalysts have been evaluated. Best results were obtained with thermally pre‐treated fatty acid methyl esters (FAMEs). The reactions performed with high efficiency with low catalyst loadings allowing TONs as high at 1000. An acetal protected acrolein was also used, enabling improvement of the reaction performances. A tandem cross‐metathesis/hydrogenation reaction without isolation of the formyl intermediate delivered the expected alcohol ester in good yield.Practical applications: The cross‐metathesis of FAMEs with acrolein provides access to a broad range of bifunctional compounds of interest for the manufacture of polymers, considering the multiple post‐transformations of the formyl group availableThe ruthenium‐catalyzed cross‐metathesis of fatty acid methyl esters with acrolein is presented. The bifunctional formyl‐esters are valuable precursors for subsequent transformations such as the tandem cross‐metathesis/hydrogenation reaction delivering a hydroxyl‐ester in one step.

This study was aimed at integrating a green separation process without phase change, namely nanofiltration, with olefin metathesis to recover the homogeneous catalyst. As the commercially available Hoveyda II catalyst was not sufficiently retained by the membrane, a set of homogeneous ruthenium‐based catalysts were prepared to enhance the recovery of the catalyst by solvent‐resistant commercial membranes made of polyimide (Starmem 228). The molecular weights of the catalysts were gradually increased from 627 to 2195 g mol⁻¹, and recovery was found to increase from around 70 % to 90 % both in toluene and dimethyl carbonate. The most retained catalyst was then engaged in a series of model ring‐closing metathesis reactions associated to a final nanofiltration step to recover and recycle the catalyst. Up to five cycles could be performed before a deterioration in the performance of the process was observed.