Short communicationSelective homocoupling of phenylboronic acid over supported Pd nanoparticle in biphase solvent

•A superhydrophilic Pd catalyst was used for the homocoupling of Ph-B(OH)2.•High selectivity of biphenyl could be obtained in a biphasic solvent of water-toluene mixture.•The biphase solvent could shift the reaction balance to the formation of biphenol.

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.