Study On The Synthesis Of Dihydroxydiphenylsulfone Developer

The synthesis and purification of dihydroxydiphenylsulfone, which is a color developer for thermal printing sheet, were studied in this paper. 2,4′-Dihydroxy– diphenylsulfone and 4,4′-dihydroxydiphenylsulfone are the primary products synthesized.2,4′-Dihydroxydiphenylsulfone was prepared from phenol and H2SO4. The synthesis of dihydroxydiphenylsulfone with boric acid, chlorosulfonic acid, aluminium chloride, phosphoric acid, phosphorous acid, phosphorous pentoxide, sodium sulfate,sodium hydrogen sulfite and p-toluenesulfonic acid as addition agent using cheaper toluene dichloride as solvent was studied in detailed. The effects of addition agent type, addition agent amount, mole ratio of phenol to sulfuric acid, reflux reaction time, solvent amount, and addition method of H2SO4 and phenol on the preparation of dihydroxydiphenylsulfone were investigated. The optimum conditions which reduced the production cost and improved economy profit were obtained. The main results were as follows:1.1g boric acid, 108g phenol, 52.6g 96% H2SO4 reflux for 2.5h in 480g toluene dichloride, addition time of phenol 10min at temperature 80～85℃. The content of 2,4′-dihydroxydiphenylsulfone was 36.73% and the content of 4,4′-dihydroxydiphenylsulfone was 53.60% in the mixed product synthesized, the total yield was 95.5%.Purification process of dihydroxydiphenylsulfone was also investigated. The separating methods used in this paper were: dissolved in alkali and separated out after addition of sulfuric acid; extracted with s-tetrachloroethane; extracted with s-tetrachloroethane and methanol-water. Then separated products were refined respectively. The better purification conditions were as follows:30g crude product were suspended in 80mL s-tetrachloroethane under heating for 1h. Then 4,4′-dihydroxydiphenylsulfone were filtrated at temperature 50℃, the content of 4,4′-dihydroxydiphenylsulfone was 89.14% in filter cake 18.3g. 5g Methanol and 45g water were added in filtration which volume was reduced to 1/3 by distillation. This mixture were heated, then laid-aside and filtrated. The filter cake 10.6g contained 2,4′-dihydroxydiphenylsulfone 80.91%. The filter cake was refined by alkaline aqueous of 1.5% NaOH 5.2g/g crude product. The purity up to 97.40% and total yield of 52.9% were obtained.4,4′-Dihydroxydiphenylsulfone was refined by alkaline aqueous of 0.6% NaOH...