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CO2 zamiast CO : katalityczna konwersja CO2 w syntezie związków karbonylowych

Wójcik Ewelina, Trzeciak Anna M.

Wiadomości Chemiczne

2021

[Z] 75, 3-4

395--422

Modem industrial carbonylation processes, leading to functionalized carbonyl compounds, are based on the application of highly toxic and flammable carbon monoxide. Recently, carbon dioxide which is non-toxic and abundant, has attracted attention as a perfect C1 source to build new C-C and C-N bonds. From the standpoint of green and sustainable chemistry, it is appealing and challenging to combine the reduction of CO2 with subsequent carbonylation using in situ formed CO. Herein we present the application of CO2 as C1 building block for the carbonylation of different organic compounds in the presence of transition metal catalysts (e.g. Pd, Rh, Ru, Fe). Industrially important organic compounds has been obtained in hydroformylation, dehydrogenation, hydrogenation, aminocarbonylation and carboxylation reactions with CO2. On the other hand, rapid reduction of CO2 to CO could processed in the metal catalyst - free systems, using a catalytic amount of fluoride salt and stoichiometric amount of di- or hydrosilane. In these reactions silyl formate has been identified as an important intermediate formed from silane and carbon dioxide. Also hydrazine and sodium borohydrate have been used for CO2 reduction to formic acid or other products. Obviously, these reactions could be restricted because of their sensitivity to the applied conditions, high cost of reactants as well as the waste generated. The presented examples of catalytic carbonylation reactions with CO2 as a source of CO group illustrate a high technological potential of this strategy.

Rola cieczy jonowych w reakcjach tworzenia wiązań C-C z udziałem katalizatorów palladowych : szczególny wpływ halogenków imidazoliowych

Trzeciak A. M.

Wiadomości Chemiczne

2006

[Z] 60, 11-12

819-843

The strategy of modification in chemical processes in order to ensure a safer, cleaner environment in the future is one of the main goal of green chemistry. The basic twelve principles of green chemistry were formulated by P. Anastas and J.Warner in 1998 and accepted by society. Following these principles chemists designing a new process should pay special attention to select substrates and chemicals that minimize their harm to the environment and to human health. Also existing chemical technologies should be modified in a similar way. One approach to achieve this goal is replacement of traditional toxic solvents (mainly VOC,s volatile organic solvents) with ionic liquids presenting a group of liquids or low-temperature melting solid salts of no vapour pressure. Application of ionic liquids in processes catalyzed by transition metal complexes meets two (or in some cases even three) green chemistry rules. The presence of ionic liquids as a solvent in catalytic systems for C-C bond forming reactions like Heck, Sonogashira, Suzuki and carbonylation offers many spectacular advantages including facilitation of catalyst separation from organic products. Elimination even traces of metals from the products of C-C coupling reactions which are used as medicines or agricultural chemicals is extremely important. An article presents catalytic systems containing palladium catalyst precursors, both soluble and heterogenized complexes as well as palladium nanocolloids applied in C-C bond forming processes performed in ionic liquids. The applicability of ionic liquids and influence of their molecular structure on the reaction course is discussed. A special attention is paid to the reactions of ionic liquids with palladium precursors leading to the formation of new species and modification of catalytic properties of the system. It is shown that in many catalytic systems a strong inhibiting effect of imidazolium halides was observed. This fact can be explain on the basis of experimental data by the reaction of imidazolium halide with palladium - aryl intermediate leading to N-heterocyclic carbene complex of lower catalytic activity. Decomposition of palladium - aryl intermediates with formation of phosphonium salts in the presence of imidazolium halide was also observed. In both above mentioned cases a key intermediate in C-C bond forming reactions, that is palladium - aryl halide complex, is eliminated from the reaction mixture causing to decrease of the final product yield. An article presents a state of knowledge in the field of ionic liquids application in catalysis and formulates expectations for future designing of catalytically active and environmentally friendly palladium based systems for C-C bond forming reactions.