Oxidation of benzene by molecular oxygen catalysed by vanadium
Oxidation of benzene by molecular oxygen catalysed by vanadium
复制标题
DOI：
10.1016/s1381-1169(03)00259-0
复制
发表时间：
2003-08-01
影响因子：
--
通讯作者：
Bonoldi, L
中科院分区：
文献类型：
--
作者：
Battistel, E;Tassinari, R;Bonoldi, L
钒化合物能有效地催化分子氧氧化苯制苯酚。该反应仅在能够再循环氧化的催化剂的还原剂存在下才是真正催化的。在所测试的还原剂中，抗坏血酸盐对苯酚的选择性和反应性最高。使用其他还原剂，如二硫醇，对更多氧化产物（即对苯二酚）获得高选择性（>96%）。反应在水/乙腈/苯混合的两相体系中进行，该体系允许反应物和产物之间的良好分离。反应速率和产物选择性取决于与钒相互作用的配体的类型以及抗坏血酸/V摩尔比。ESR测量证实，在初始添加（VCl 3）-Cl-III之后，在反应介质中迅速形成V-IV物种。此外，所观察到的苯氧化的初始诱导期可以与形成的olicomeric V-IV物种，通过ESR分析评估，而不是V-抗坏血酸络合物的缓慢形成。(C)2003 Elsevier Science B. V.保留所有权利。
Vanadium compounds can efficiently catalyse the oxidation of benzene to phenol with molecular oxygen. The reaction is truly catalytic only in the presence of a reducing agent able to recycle the oxidised catalyst. Among the reducing agents tested, ascorbate afforded the highest selectivity and reactivity to phenol. With other reductants, such as dithioalcohols, high selectivity (>96%) was obtained toward more oxidised products (i.e. hydroquinone). The reactions were performed in the two-phase system formed by mixing water/acetonitrile/benzene which allows a good separation between reactant and product. The reaction rate and product selectivity depend upon the type of ligand interacting with vanadium as well as upon the ascorbate/V molar ratio. ESR measurements confirmed that V-IV species is rapidly formed in the reaction medium after the initial addition Of (VCl3)-Cl-III. Moreover, the observed initial induction period of benzene oxidation can be related to the formation of olicomeric V-IV species, as assessed by ESR analysis, rather than to the slow formation of V-ascorbate complex. (C) 2003 Elsevier Science B.V. All rights reserved.