On Phenylphenol, Biphenyl

P-phenylphenol (PPP for short) is an important intermediate and it is a starting material for manufacture of pharmaceuticals and dyes, etc. But at present, the manufacture of p-phenylphenol in China is unsatisfactory with low yield and high pollutions.From diphenyl as starting material, p-phenylphenol is obtained through sulfonation using concentrated sulfuric acid as sulfonating agent and alkali fusion using sodium hydroxide. The influences of reaction conditions such as reaction temperature, reaction time and ratio of reactants have been studied.The optimal reaction conditions were that, for step 1: diphenyl (10g), 98% concentrated sulfuric acid (6.4mL), the temperature of adding diphenyl was about 70～80℃, the reaction temperature was 130～140℃, and the reaction time was 5h. For step 2: intermediate product 4-biphenylsulfonic acid sodium salt (16g), the reaction temperature was 320～30℃and the reaction time was about lh. Then alkali fusion of 4-biphenylsulfonic acid sodium salt using sodium hydroxide (20.8g) gave p-phenylphenol in high yield. The yield had obviously increasing when mother liquid is reused. This process could meet the industrialized production due to the fact that the method had high yield, easy operation and low cost.