无碱条件下氧气催化氧化2-乙基己醇合成2-乙基己酸

Base-free Catalytic Oxidation of 2-Ethylhexanol to 2-Ethylhexnoic Acid with Oxygen

以2-乙基己醇作为原料,O_2作为氧化剂,无碱参与下催化氧化合成2-乙基己酸。使用气相色谱(GC)进行定量分析,气质联用仪(GC-MS)进行定性分析。考察了催化剂、溶剂、反应温度、时间及氧压力对反应的影响。结果表明:2,2,6,6-四甲基哌啶氮氧自由基(TEMPO)/硝酸铜为合适的催化剂体系,乙酸乙酯为合适的溶剂。适宜的反应条件是:催化剂TEMPO用量为2-乙基己醇物质的量的5%、硝酸铜用量为2-乙基己醇物质的量的4%,100℃、0.5 MPa O_2压力下反应6 h,2-乙基己酸收率可达77.1%。O_2恒压条件下该反应是拟一级反应,反应活化能为59.9 k J/mol。主要副产物是3-庚醇和3-庚酮。

2-ethylhexnoic acid was prepared by catalytic oxidation of 2-ethylhexanol using O2 as an oxidant under a base-free condition. The quantitative analysis was performed by gas chromatography（ GC）,and the qualitative analysis was carried out by GC-MS. The effects of different catalysts,different solvents,reaction temperature,reaction time and oxygen pressure on the yield of the product and conversion of the raw material were investigated. The results showed that 2,2,6,6-tetramethylpiperidineoxyl（ TEMPO） / copper nitrate hydrate was an efficient catalyst system,and ethyl acetate was a suitable solvent The optimum reaction conditions for synthesis of 2-ethylhexnoic acid were obtained. The yield of 2-ethylhexnoic acid could reach 77. 1%,when TEMPO was 5 mol% of 2-ethylhexanol,copper nitrate hydratewas 4 mol% of 2-ethylhexanol at 0. 5MPa O2,100 ℃ for 6 h. Under the constant oxygen pressure,the reaction is a pseudo first order reaction and the activation energy is59. 9 k J / mol. The main by-products are 3-heptanol and 3-heptanone.