Palladium chloride and a compliment of different bases were studied for their effectiveness in aqueous solution based Suzuki Cross Coupling reactions. A combination of catalyst and different bases were investigated for their effects on the reaction products, both the cross-coupled and the homo-coupled products. The bases investigated were: K2CO3, NaHCO3, Na2SO4, K3PO4, and H2KPO4 for the coupling of phenylboronic acid with 4-bromonitrobenzene. All studied bases favored more of the cross-coupled product, 4-nitrobiphenyl, than the homo-coupled product, biphenyl. The reactions were performed using a CEM Discover microwave reaction unit at 80°C, in 18 MΩ deionized water, for 10 minutes. The general trends observed in the study showed that both the HCO3- and the CO32- had the highest amount of cross-coupled products (80-90%) and no observable effect on the product ratios from increasing the concentration of the base from 2.0 to 16 mM. Whereas, the PO43- and the H2PO4- showed a decrease in the amount of cross-coupled product as the base concentration was increased from 2.0 mM to 16 mM. The SO42- showed an increase in the cross-coupled products with increasing base concentration from 2.0 mM to 8.0 mM. However, above 8.0 mM the reaction shifted to produce more homo-coupled than cross-coupled product.

Aqueous solution palladium catalyzed Suzuki cross coupling reactions: Reaction optimization of base and the effects of base concentration

253rd National Meeting (2017)

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