The goal of this master thesis was to determine optimal reaction parameters of the Suzuki-Miyaura reaction under green conditions with the usage of the palladium precatalyst [Pd(Py-tzNHC)2](BF4)2. During the optimization we tried to follow the principles of green chemistry, which meant the usage of enviromentally friendly solvents and bases and low temperature of the reaction mixture. In process we also tried to use low loading of palladium catalyst. A model reaction was chosen to determine the most efficient base and solvent. Conviniently, water turned out to be the solvent of choice for studied reaction, which fits perfectly into the principles of green chemistry. The screening of bases showed that potassium carbonate (K2CO3), potassium phosphate (K3PO4) and disodium hydrogenphosphate heptahydrate (Na2HPO4·7H2O) were the most efficient bases. Since the above bases gave comparable results, the selection of base for further reactions (K2CO3) was made on the basis of its price and environmental friendliness. After the reaction parameters were determined, the efficiency of the method was tested on different substances. Besides the influence of the temperature, base and reaction time on the conversion rate, the electronic-influence and steric hindrance of substituents on substrates were found to play important role. Likewise, the type of halogen atom (Cl, Br, I) is crucial for (in)activity of this substrate. The selection of the substrates was based on the possibility of observing the effect of different groups on aryl boronic acids and aryl halides on the conversion rate.We have varieted different subsituents on both, aryl halides and boronic acids. We have also tested different (hetero)aryls and (hetero)boronic acids. High yields of products were obtained in the case of aryl bromides, whereas aryl chlorides returned low conversions of starting material.
Besides the precatalyst efficiency on Suzuki-Miyaura reaction, we also wanted to determine the catalytic pathway, starting with determination whether the catalysis is either homogeneous or heterogenous. Mercury poisioning experiments confirmed that the system is operating via homogeneous catalysis. We tried to determine the course of reaction and improve the isolation process. We postulated that carbonate ion reacts with boron atom of boronic acid and creates tetravalent boron ion, which further reacts with the product of oxidative addition.
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