Determination of biphenyl in the presence of polyphenyls : Water solubility method

Prior work had shown that the principal products of the pyrolysis of p-terphenyl are biphenyl and certain higher polyphenyls. Since the three terphenyls as well as particular higher polyphenyls are being investigated as heat transfer media for atomic energy reactors, the determination of biphenyl, as a major or minor product of their pyrolysis, becomes of prime importance in order to follow the trend of reaction products.Because of the greater solubility of biphenyl in water, as compared to other polyphenyls, biphenyl is completely extracted from such mixtures by water and can be determined spectrophotometrically in aqueous solution. Effects of temperature, rates of solution, and the presence of polyphenyls were studied. The solubility of biphenyl is about 0.9 mg/100 ml of water, but the suggested working limit in 0.4 mg biphenyl/100 ml of solvent.As little as 0.1% biphenyl in p-terphenyl may be detected and as high as 20% may be determined in higher polyphenyls.