Biphenyl is soluble in water at 4.45 mg/L. The chemical is soluble, however, in numerous organic solvents.
Biphenyl is a very nonpolar type of molecule, and a reason behind this is that it bonds to itself through nonpolar van der Waals interactions. This is why it cannot mix well with water, which is a polar molecule. Polar and nonpolar molecules do not mix. This is why nonpolar molecules like biphenyl are referred to as hydrophobic, which means they do not interact well with water.
According to research conducted by the Oral Roberts University, biphenyl was found to be soluble in a number of organic solvents, however. Some of these solvents included 1,2-dibromoethane, 1,2-dichloroethane, 1-butanol, 1-heptanol, 1-hexanol and 1-octanol.