Submitted to the European Journal of Organic Chemistry 1 This is a post-print version for exclusive noncommercial use of students and colleagues MICROREVIEW DOI: 10.1002/ejoc.200((will be filled in by the editorial staff)) European Journal of Organic Chemistry, 2012, 32, 6309-6320 http://dx.doi.org/10.1002/ejoc.201200709 Immobilized Catalysts for Hydroformylation Reactions: A Versatile Tool for Aldehyde Synthesis Ângela C. B. Neves, [a] Mário J. F. Calvete, [a] Teresa M. V. D. Pinho e Melo [a] and Mariette M. Pereira [a] * Keywords: Hydroformylation / Supported catalysts / Heterogeneous catalysis / Immobilization Olefin hydroformylation is a process widely used, both in large scale and in fine chemistry, with catalyst reuse being still one of the main objectives. In recent years, developments on the immobilization of catalysts on solid supports that enable its recovery and reuse when applied in catalytic hydroformylation of aromatic and aliphatic olefins permitted a boost in the field of heterogeneous catalysis. In this review the most relevant results reported over the last five years are presented, concerning the development and use of supported catalysts in mesoporous materials, hydrotalcite, carbon materials and nanoparticles applied in catalytic hydroformylation of olefins. Moreover, a critical analysis of the results, especially concerning reusability and leaching issues is presented. ____________ [a] Department of Chemistry, University of Coimbra, Rua Larga, 3004- 535 Coimbra Portugal Fax: +351239827703 E-mail: mmpereira@qui.uc.pt Introduction The hydroformylation reaction was firstly discovered by Otto Roellen in 1938 [1] when working on the development of Fischer- Trops reaction in Ruchermie industry. This transition metal complexes catalyzed reaction, involves the cis addition of hydrogen and carbon monoxide to olefins, yielding aldehydes in one step, with 100% atomic economy, Scheme 1. [2] Scheme 1. Hydroformylation reaction. It is currently considered one of the most used industrial homogeneous catalytic processes for the synthesis of aldehydes or alcohols (more than 6 million ton/year) and their relevance is well documented by the number of books and reviews articles on the subject. [3] Initially, the reaction was only applied to the industrial synthesis of bulk chemistry products, [4] but nowadays there is a high demand for the production of new aldehydes as precursors of several high commercial value compounds. [5] The hydroformylation of long chain olefins is of great interest due to high industrial applicability of aliphatic aldehydes, namely in production of detergents, plasticizers, solvents or surfactants. On the other hand, branched chiral aldehydes have also an impressive range of applications in pharmaceutical and cosmetic industry, being used, for instance, as precursors in the synthesis of ant- inflammatory drugs such as ibuprofen and naproxen. [6] Nevertheless, the search for new active, selective and reusable catalysts is still extremely relevant in order to widen the range of applications of the hydroformylation reaction in fine chemistry industrial processes. One of the main synthetic strategies to achieve these goals is based on the development of new homogeneous immobilized catalysts into solid supports, which allows not only its easy separation/reutilization but also the possible enhancement of its activity and selectivity by confinement effects. [7] Supports must be chemically, thermally and mechanically stable, with high surface areas and/or appropriate pore sizes, in order to let easy reagent diffusion. Several solid supports have been developed so far, namely organic polymers and inorganic materials such as SiO2, Al2O3, MgO, ZnO, clays, activated carbon and zeolites. [8] This review covers the more relevant contributions of the last five years, regarding the development and use of immobilized catalysts on mesoporous materials, silica, hydrotalcite, carbon materials and magnetic nanoparticles applied in metal catalyzed hydroformylation of olefins.