直接氧化法制备2,5-二氯苯酚

Preparation of 2,5-dichlorophenol by direct oxidation

2,5-二氯苯酚是重要的酚类化合物,工业上常用的2,5-二氯苯酚的制备方法大多存在生产流程长、污染严重等问题。针对这些问题,本文提出了以对二氯苯为原料、H_2O_2为氧化剂的直接氧化制备2,5-二氯苯酚的工艺,并对催化剂和溶剂进行初步筛选,探讨了不同催化体系对反应的影响,确定以铁粉作催化剂、乙酸为溶剂的反应体系下,通过对氧化剂用量、反应温度、反应时间、催化剂用量等工艺条件的考察,获得最佳工艺条件。实验结果表明,当工艺条件为n(对二氯苯)∶n(50%H_2O_2)∶n(Fe)=1∶3∶0.10、反应温度60℃、反应时间2.5h时,反应效果最佳;产物经GC-MS和1HNMR分析确定为2,5-二氯苯酚,经气相色谱分析,2,5-二氯苯酚选择性达83.4%,收率达42.6%。

2,5-Dichlorophenol is an important phenolic compound. Regarding the preparation of 2,5-dichlorophenol, most of the preparation methods commonly used in the industry have problems such as long production process and serious pollution. The process of preparing 2,5-dichlorophenol by direct oxidation of dichlorobenzene as raw material and H2 O2 as oxidant. The catalysts and solvents were initially screened to investigate the effects of different catalytic systems on the reaction. The process conditions of oxidant dosage, reaction temperature, reaction time and catalyst dosage were determined by using iron powder as catalyst and acetic acid as solvent. The experimental results showed that the best process conditions were n(p-dichlorobenzene)∶n(50% H2 O2)∶n(Fe) = 1∶3∶0.10, the reaction temperature was60℃ and the reaction time was 2.5 h. The product was identified as 2,5-dichlorophenol by GC-MS and1 H NMR analysis. The gas chromatographic analysis showed that the selectivity of 2,5-dichlorophenol was83.4% and the yield of 2,5-dichlorophenol was 42.6%.