| 2,6-dihydroxytoluene is one of the important fine chemical engineering intermediates. It can be widely used for medication, pesticide, dye, dyestuff and so on.2,6-dihydroxytoluene was synthesized from 2.6-diaminotoluene in acid system through direct hydrolysis in the high temperature and pressure conditions in this paper. Synthetic technology and extraction technology of 2,6-dihydroxytoluene were mainly studied. The product and intermediate were identified by IR, GC/MS and 1H-NMR, and the mechanism was initially discussed.By comparing direct preparation technology of 2,6-dihydroxytoluene in the sulfuric acid system, ammonium bisulfate system, the organic acid system, and phosphoric acid system, the results showed that the effect of phosphoric acid system was the best. We focused on the synthetical technology of 2,6-dihydroxytoluene in the phosphoric acid system. The optimum reaction conditions were getted by the means of single factors and orthogonal analysis:reaction temperature of 220℃, reaction time of 6h, n(H3PO4):n(2,6-diaminotoluene): n(H2O)=7:1:60, Under these conditions, the conversion of 2,6-diaminotoluene was 100%, the average yield of 2,6-dihydroxytoluene was up to 96.3%, its purity was 98.5%, and the recrystallization purity was 99.3%. The paper studied the continuous reaction of mother liquor, which could be applied at least six times.The extraction technology in post processing was mainly researched in this paper. we used solvent extraction method by using ethyl acetate as solvent extraction to study extraction technology of the reaction solution. The better extraction technology condition was that extractant was ethyl acetate, extraction temperature was 25℃, extraction time was 30min, the setting time was 1h. the phase ratio was 1.2, the extraction rate could reach 95%. If it was extracted three time, the extraction rate could reach 98%. At the same time, liquid-liquid equilibrium data for the three-system 2,6-dihydroxytoluene-water-ethyl acetate were measured. And the triangular phase diagram, the distribution curve graph and the selective curve graph were drawed. The equilibrium data were related with Hand equation. |
