دانلود رایگان مقاله هوموکوپلینگ انتخابی اسید فنیل بر نانوذرات پالادیم حمایت شده در حلال biphase

Abstract

We reported an effective method to improve the biphenyl selectivity by employing a biphasic solvent of water-toluene mixture over hydrophilic Pd catalyst. The coupling reactions occurred in water, and the biphenyl product formed in water could be immediately extracted into the toluene, leading to the shift of reaction balance to the formation of biphenyl. By using a hydrophilic Pd catalyst, the conversion of phenylboronic acid and biphenyl selectivity could reach as high as 99.0 and 83.0%, respectively, which are much higher than those in mono-phase solvent under the same conditions. More importantly, the heterogeneous Pd nanocatalyst exhibited excellent recyclability.

4. Conclusion

In summary, we report an efficient bi-phase water-toluene solvent for the aerobic homocoupling of phenylboronic acid to biphenyl. By employing superhydrophilic Pd/MCM-41 as catalyst, the selectivity to biphenyl could reach 83.0% with 99.0% conversion of phenylboronic acid, which are much higher than those in the conventional monophase solvent. The good catalytic performances are reasonably attributed to the synergistic effect of bi-phase water and toluene, which are favorable for shifting the reaction balance to the formation of biphenyl. This work would be helpful for developing more efficient strategies for coupling reactions in the future.