Modern Approaches to the Creation of Immobilized Metal-Complex Catalysts for Hydrogenation, Alkene Metathesis, and Cross
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MODERN APPROACHES TO THE CREATION OF IMMOBILIZED METAL-COMPLEX CATALYSTS FOR HYDROGENATION, ALKENE METATHESIS, AND CROSS-COUPLING PROCESSES: A REVIEW M. O. Ivanytsya, 1,2 S. V. Ryabukhin, 2,3 D. M. Volochnyuk,2,3,4 and S. V. Kolotilov1
UDC 544.2; 54-44; 544.47
The approaches to immobilization of metal-complex catalysts for organic processes of hydrogenation, alkene metathesis, and cross-coupling on silica and polymeric and other carriers are considered. The advantages and lack of modern approaches to the creation of such systems are analyzed. It was shown that the stability of the catalyst with immobilized metal complex in the respective process was directly related to the mechanism of its catalytic action, namely, ligand cleavage in the catalytic cycle. Among the considered catalysts for various types of reactions, the catalysts for hydrogenation processes had the highest stability; this peculiarity is associated with specific features of their action.
Keywords: metal-complex catalysts, immobilization, hydrogenation, metathesis, cross-coupling.
INTRODUCTION Metal complex catalysts (MCC) are widely used in modern industrial and fine organic synthesis. For example, as of 2000, 80% of world acetic acid production was based on methanol carbonylation reaction in the presence of rhodium or iridium complexes [1], and one of the ways of methyl methacrylate synthesis is carbonylation of methyl acetylene in the presence of palladium complexes [2]. The advantages of MCC when compared to oxide or metal catalysts include significantly higher activity and the ability to carry out a large amount of different processes, as well as achieving higher selectivity due to the specificity of action - activation of well-defined functional groups [3]. It can be noted that the activity of MCC often exceeds the activity of catalysts that contain particles of the corresponding metal on the carrier. For example, the activity of the Pd(PPh3)4 catalyst of cross-coupling reactions of the 1st generation [4] in the Suzuki reaction significantly exceeds the activity of the best samples of Pd/C [5], and modern MCCs can be 100 or more times more active than Pd(PPh3)4. In most cases the main disadvantage of MCC is the high cost associated with the complexity of the synthesis of ligands and the process of production of such catalysts, which limits their use in large-scale production of organic matter. The disadvantages of MCC also include the difficulty of purification of the product from trace amounts of catalyst when the process ________ 1 L. V. Pysarzhevsky Institute of Physical Chemistry, NAS of Ukraine, Kyiv, Ukraine. E-mail: [email protected]. 2 Institute of High Technologies, Taras Shevchenko National University of Kyiv, Kyiv, Ukraine. 3 LLC Research and Production Enterprise “Enamine,” Kyiv, Ukraine. 4 Institute of Organic Chemistry, NAS of Ukraine, Kyiv, Ukraine. ___________________________________________________________________________________________________ Translated from Teoretychna ta Eksperymentalna Khimiya, Vol. 56, No. 5, p
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