Practical and theoretical aspects of CdSe-CdS heterojunctions

Imperial Users onl

Effects on Altering Reaction Conditions in Suzuki Cross Coupling Reactions Using the Microwave

Over the last few decades, Suzuki coupling has become a common process for the synthesis of intermediates in pharmaceutical and industrial applications. It is well known that palladium is an effective catalyst for the formation of cross-coupled products. Therefore, this catalyst was tested in a series of reactions. Also, it is believed that other catalyst with similar properties to palladium can work, for example cerium. Therefore, a cerium hydroxide catalyst was synthesized in lab and used as a potential catalyst for the Suzuki reaction. For this study, some bases were investigated (NaOH, Na2CO 3, K3PO4, NaNO3, NaHCO3, etc) for the coupling of boronic acid with various organohalides. The reactants consisted of phenylboronic acid at a constant concentration of 1 mMol and of either 4-bromoanisole, 4-bromotoluene, bromobenzene, 4-bromonitrobenzene or 4-bromochlorobenzene at 1.5 mMol. All reactions under a palladium catalyst extensively favored the cross-coupled product (4-nitrobiphenyl, 4-methoxybiphenyl, 4-methylbiphenyl, 4-chlorobiphenyl) as expected, having the homo-coupled product (biphenyl) at an extremely low yield. These reactions were performed using a CEM discover microwave reaction unit, with alternating temperatures of (40 °C, 50 °C, 60 °C, and 70 °C) in 5mL propanol. Characterization of reaction products were analyzed using gas chromatography flame ionization detector (GC-FID) and gas chromatography mass spectroscopy (GC-MS) to identify and quantify cross and homo coupled products