Research On Green Catalytic Hydroxylation Of O-Cresol

Heterogeneous catalytic reaction is an important research topic, has achieved prodigious development. Phenolic compounds is an important industrial raw materials, which normally needs indirect synthesis, therefore the production process is more complicated. In theory, it is feasible to directly hydroxylating to synthesize hydroxybenzene by green oxidants which are air, oxygen and hydrogen peroxide. In recent years, there are a large number of investigations about how to directly hydroxyl ate benzene to prepare Phenol and how to directly hydroxylate phenol to prepare dihydroxybenzene. But the research about direct hydroxylation of other displaced hydroxybenzene was reported a fat lot. Because of the concerted effect of substitutes, the selectivity of reaction which displaces the unfavorable place is extraordinarily low. And the derivates of products hydroxylated by o-cresol, which is methyldihydroxybenzene, are important intermediate of fine chemical engineering and the additional value are considerable.It is the most potentially industrial process that hydroxyl free radical directly substitutes the hydrogen atom on aromatic ring and the selection of catalyzer was the key of direct hydroxylation. This dissertation researched the preparation condition of copper hydroxyphosphate (Cu₂(OH)PO₄) and the process for synthesizing methyldihydroxybenzene by directly hydroxylating o-cresol with copper hydroxyphosphate prepared by myself. We could carry out cleanly catalytic oxidation with coupled reaction in allusion to the problem of deepness oxidation in the hydroxylation process. As a result, the cost of copper hydroxyphosphate was low, the process was easy and it had good catalytic activity. It was a process that methyldihydroxybenzene synthesized by hydroxylating o-cresol with hydrogen peroxide, which had greater industrial foreground.The catalyzer copper hydroxyphosphate has been synthesized successfully by a hydrothermal process from ethylenediamine, phosphoric acid, and copper acetate. The matching of materials was researched. And homogeneous design was made at these bases. The preparation condition was optimized and the stable preparation condition of catalyzer was educed. The preferable preparation condition was that the mol centage of ethylened- iamine, phosphoric acid, copper acetate and water were 0.24:2.28:1.74:95.74.Its structure were analyzed and measured by the techniques of XRD, IR,DTA/TG and SEM. The result of hydroxylating o-cresol showed that copper hydroxyphosphate had higher activity.The process of synthesizing methyldihydroxybenzene by hydroxyladating o-cresol with the catalyst made by myself was investigated. The factors such as the kind and dosage of solvent, dosage of catalyzer, matching of material, reacting temperature, reacting time and infusing speed of hydrogen peroxide were discussed. The preferable condition received from the experimental results: dosage of acetic acid solution was 10ml(o-cresol 0.2g),the mass ratio of catalyst and o-cresol was 1: 20,the mol ratio of o-cresol and hydrogen peroxide was 1:1, reacting temperature was 70℃,reacting time was 1.5h.In this operating condition, the conversion of cresol was 70～90%,the total selectivity of methyldihydroxybenzene was 14.59%.Under the optimal operating condition, the deepness oxidation of hydroxylating o-cresol was rearched. The goudron was depressed by competing reaction with dimethyl sulfoxide as coupling agent, the experimental process displayed that the color of liquid became brown soon and got black after the hydrogen peroxide was affiliated ultimately. When the coupling agent was not affiliated in the reacting system, a lot of goudron could be discovered in the final product. When the coupling agent was affiliated in the reacting system, the color of liquid didn't become black and the goudron was not discovered in the final product. It achieved a clean catalytic hydroxylation result. At this moment, the mol ratio of dimethyl sulfoxide and o-cresol was 8:10.