Synthesis And Refine Of2,6-Dihydroxynaphthalene

2,6-Dihydroxynaphthalene is used as a precursor in the manufacture of highperformance polyester resins such as polyethylene naphthalate polymer(PEN) andliquid crystal polyester resin, which is widely used in fiber, packaging containers, filmand electronic components, dyestuff and medicine etc. In this article, the synthesis ofcrude2,6-dihydroxynaphthalene is prepared by cheap disodium2,6-naphthalenedisulfonate on the high temperature mixed alkali fusion step reaction,and then we studied the physicochemical data and purification method of the crude2,6-dihydroxynaphthalene. So we find a suitable for industrial preparation andpurification process, which is low energy consumption, convenient operation, lesswastewater. The main results are as follows:2,6-Dihydroxynaphthalene was synthesized by one-pot alkali fusion using cheapdisodium2,6-naphthalenedisulfonate as raw material. The results showed that N2,phenol or antioxidant1010is crucial to prevent overoxidation, which significantlyimproved the yield of2,6-dihydroxynaphthalene. We identified the optimumtechnological conditions: when the mass ratio of disodium2,6-naphthalenedisulfonateand alkali=1:3, the mass ratio of sodium hydroxide and potassium hydroxide were2:1in mixed alkali, the reaction temperature was maintained at345℃and the yieldof the product reached high up to86.3%.We used a single solvent and mixed solvent method of purification. Manysolvents have been selected, including toluene, butyl acetate, ethyl acetate, n-butanol,isobutanol, isopropyl alcohol, heptane, acetone, ethanol, methanol and butylacetate/n-butanol, isobutanol/n-heptane, acetone/heptane, isopropanol/water, Y/water,G/water mixed solvents.We explored the effects of solution temperature, time, solvent refine method onthe purity of the product in the purification process. The improved process wasapplied as follow: m(activated carbon):m (crude product): v (isobutyl alcohol)=0.1:1:3, and the mixture were stirred and refluxed for30min, then cooled, filtered, andhigh-purity product was obtained. The purity of product was99.02%. m(activatedcarbon): m (crude product): v (isopropyl alcohol): v (water)=0.1:1:3:9, the purity of product was over98.09%and the yield was68%. The product purity obtained by theprocess was high, white powder crystal. The improved process was cheaper andenvironmentally friendly, and was easy to be operated and industrialized.