Biphenyl is an organic compound with chemical formula is C12H10. It is white or slightly yellow flake crystal with unique fragrance. Its melting point is 71℃, boiling point is 255.9℃, relative density is 0.992, and refractive index is 113℃. It is insoluble in water, but soluble in ether, ethanol, carbon tetrachloride, alkane, aromatic hydrocarbon, etc. Biphenyl is similar to benzene in chemical properties and can be chlorinated, nitrated, sulfonated and hydrogenated. It is mainly used as solvent, heat transfer agent, fruit mildew inhibitor, and can also be used in organic synthesis.