Preparation of rhodium (0) nanoparticles on mesoporus support assisted by quaternary ammonium salts : application to asymmetric hydrogenation of prochiral arenes

This thesis aims to develop new catalysts combining Rh(0) nanoparticles with promising activities and the confinement effect of mesoporous materials for applications in asymmetric hydrogenation in water. Particles were prepared by the reaction of NaBH4 with RhCl3, directly, within silicic (SBA-15) or aluminosilicic (Al-SBA-15) mesostructured materials with assistance of quaternary ammonium salts. A first set of materials was obtained by testing 13 molecules of "free" stabilizing agents varying in chain length, polar head or counter-ion. In this case, structures including from 12 to 16 carbon atoms led to better metal dispersions. Strong electrostatic interactions with Al-SBA-15 have been highlighted for C16H33N(CH3)2(CH2CH2OH)+ Cl-. In a second step, equivalents ammonium salts were covalently grafted (via their carbon chain) on SBA-15 or Al-SBA-15 proceeding by nucleophilic attack of chloropropyl groups (co-condensation) by N,N-dimethylethanolamine. The conditions of implementation of the substitution reaction had to be optimized to minimize side reactions between the amine and the free silanol groups. Rh(0) nanoparticles of both series catalyze the hydrogenation of diphenylmethane at room temperature and under 1 bar of H2. Ammonium salts with asymmetric centers have also been studied leading to catalysts of ethylpyruvate and m-methylanisole hydrogenation working in water under 40 bar of H2 and affording slight enantiomeric excess.

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Source https://theses.hal.science/tel-00834363
Author Sassine, Rita
Maintainer CCSD
Last Updated May 10, 2026, 17:23 (UTC)
Created May 10, 2026, 17:23 (UTC)
Identifier NNT: 2012PA066053
Language fr
Rights https://about.hal.science/hal-authorisation-v1/
contributor Laboratoire de Réactivité de Surface (LRS) ; Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut de Chimie - CNRS Chimie (INC-CNRS)-Centre National de la Recherche Scientifique (CNRS)
creator Sassine, Rita
date 2012-03-27T00:00:00
harvest_object_id 756670d0-28a3-4c8b-a777-4ffdf85b73b1
harvest_source_id 3374d638-d20b-4672-ba96-a23232d55657
harvest_source_title test moissonnage SELUNE
metadata_modified 2025-08-12T00:00:00
set_spec type:THESE