以30%的双氧水为氧化剂,钨酸钠与含N或O的双齿有机配体(草酸)形成的络合物为催化剂。在无有机溶剂、无相转移剂的条件下,研究了环己酮氧化制己二酸的反应.研究结果表明,用廉价的草酸为配体,最佳反应条件为钨酸钠:草酸:环己酮:30%的双氧水的物质的量比为2.0:3.3:100:350,在92℃下反应12h。可制得80.6%的己二酸;用GC—MS跟踪了氧化过程中三种主要物质环己酮、己内酯及己二酸含量随反应时间的变化关系,提出了其主要氧化机理为环己酮首先经Beayer—Villiger氧化反应生成己内酯,己内酯进一步氧化成己二酸.
The oxidation of cyclohexanone to adipic acid by 30% aqueous hydrogen peroxide catalyzed by coordination compound system formed in situ between sodium tungstate and didentate ligands containing N or O atom such as oxalic acid without phase transfer agent and organic solvent was investigated. It was found that the optimal condition of reaction is reactant molar ratio of sodium tungstate dihydrate/oxalic acid/cyclohexanone/30% aqueous hydrogen peroxide=2.0/3.3/100/350, the reaction time of 12 h and temperature of 92 ℃ with 80.6% yield of adipic acid. According to the identification of the products by the GC-MS in the progress of reaction, the mechanism was proposed. In the reaction cyclohexanone is firstly oxidized to e-caprolactone through Beayer-Villiger reaction and then the intermediate soon oxidated to adipic acid.