对叔丁基苯酚羟基化反应的研究

采用Fe(OH)3+有机络合剂+H2O2系统,对羟基化法由对叔丁基苯酚(PTBP)制备对叔丁基邻苯二酚(4-TBC)的反应进行了研究。探讨了反应时间、反应温度、催化剂用量、n(H2O2)∶n(PTBP)、溶剂类型等因素对反应的影响。实验结果表明,溶剂类型和n(H2O2)∶n(PTBP)对催化剂的活性影响较大。在PTBP0.80g、n(H2O2)∶n(PTBP)=1.0、乙腈水溶液(乙腈与水体积比2∶1)30mL、Fe(OH)30.05g、邻苯二酚0.05g、反应温度55℃、反应时间60min的条件下,PTBP转化率可达18.5%,4-TBC选择性达89.2%。对反应机理的探索表明,Fe3++H2O2系统中的羟基自由基(.OH)不能对PTBP进行羟基化反应;Fe3++有机络合剂+H2O2系统中以活性铁氧络合物为氧化剂,与有机酚类反应物有良好的反应亲和力,能顺利完成PTBP的羟基化反应。

4-tert-Butyl-Phenol Hydroxylation

4-tert-Butylcatechol(4-TBC) was synthesized from 4-tert-butyl-phenol(PTBP) by hydroxylation with Fe(OH)3+organic complexing agent+H2O2 system.Effects of reaction time,reaction temperature,catalyst dosage,n(H2O2) ∶n(PTBP),solvent type and cocatalyst dosage on the hydroxylation were investigated.The results showed that the solvent type and n(H2O2) ∶n(PTBP) played important roles in the hydroxylation.Under the conditions: PTBP 0.80 g,n(H2O2) ∶n(PTBP)=1.0,acetonitrile-water mixture(volume ratio 2 ∶1) as the solvent 30 mL,Fe(OH)3 0.05 g and catechol as the cocatalyst and complexing agent 0.05 g,reaction temperature 55 ℃ and reaction time 60 min,PTBP conversion was 18.5% and selectivity to 4-TBC reached 89.2%.Discussion of the reaction mechanism showed that PTBP could not be hydroxylated by hydroxyl radical(·OH) formed in Fe3++H2O2 system;in Fe3++organic complexing agent+H2O2 system,an active iron-oxygen complex was formed,which had good affinity with the reactant PTBP.