共查询到19条相似文献,搜索用时 93 毫秒
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《应用化工》2016,(8)
以乙醛酸与愈创木酚为原料合成香兰素,分别对其缩合反应、氧化反应做了考察。结果表明,缩合反应较优反应条件为:物料滴加加入,反应温度为35℃,反应时间为6 h,n(乙醛酸)∶n(愈创木酚)∶n(氢氧化钠)=1∶2∶3,未反应愈创木酚先用甲苯萃取,再用氢氧化钠溶液反萃取,用于下次反应;氧化反应较优反应条件为:硫酸铜为氧化剂,n(硫酸铜)∶n(3-甲氧基-4-羟基扁桃酸)=2.4∶1,反应温度为95℃,反应体系pH=13,反应时间为7 h,氧化剂使用双氧水再生。缩合产物收率达到89.5%,氧化产物收率达到98.2%,香兰素精品收率可达到80%,纯度99.8%,高于以往文献报道。 相似文献
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《应用化工》2022,(8)
以乙醛酸与愈创木酚为原料合成香兰素,分别对其缩合反应、氧化反应做了考察。结果表明,缩合反应较优反应条件为:物料滴加加入,反应温度为35℃,反应时间为6 h,n(乙醛酸)∶n(愈创木酚)∶n(氢氧化钠)=1∶2∶3,未反应愈创木酚先用甲苯萃取,再用氢氧化钠溶液反萃取,用于下次反应;氧化反应较优反应条件为:硫酸铜为氧化剂,n(硫酸铜)∶n(3-甲氧基-4-羟基扁桃酸)=2.4∶1,反应温度为95℃,反应体系pH=13,反应时间为7 h,氧化剂使用双氧水再生。缩合产物收率达到89.5%,氧化产物收率达到98.2%,香兰素精品收率可达到80%,纯度>99.8%,高于以往文献报道。 相似文献
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3-乙氧基-4-羟基扁桃酸的合成研究 总被引:4,自引:1,他引:4
以邻羟基苯乙醚 (乙基愈创木酚 )和乙醛酸为原料 ,在碱性条件下发生缩合反应 ,合成了 3 乙氧基 4 羟基扁桃酸 ,此物质是以乙醛酸法制备乙基香兰素的中间体。通过对反应条件的优化发现 ,此合成反应的最佳反应温度为 5 0~ 60℃ ,最佳碱浓度范围为 2 0~ 4 4M ,最佳缩合反应时间为 3 5~ 8h。同时采用碱溶液的部分滴加方式 ,可使缩合反应在较短的时间内完成 ,收率达 80 %以上 ,未反应的乙基愈创木酚可以回收。 相似文献
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愈疮木酚和乙醛酸合成香兰素研究 总被引:7,自引:0,他引:7
对愈疮木酚和乙醛酸缩合—氧化合成香兰素路线进行了中等规模的研究。当反应温度为5 0℃ ,pH值为 12 ,愈疮木酚和乙醛酸物质的量比为 1 5∶1 0 ,缩合反应中乙醛酸的转化率可至90 %。以氢氧化铜为催化剂 ,以氧气为氧化剂 ,在pH值为 12 5和 94℃下反应 ,氧化产率为94%。香兰素的总收率 (以乙醛酸为基准 )为 70 %~ 72 %。生产废水经简单处理后可重复使用 ,并不影响收率 ,废水量可控制在 5t/t香兰素的水平。 相似文献
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Rajendra G. Kalikar Ramesh S. Deshpande Sampatraj B. Chandalia 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1986,36(1):38-46
Synthesis of vanillin and 4-hydroxybenzaldehyde from guaiacol and phenol, respectively, was investigated. The condensation of guaiacol and phenol with glyoxylic acid in an aqueous alkaline medium resulted in the formation of 3-methoxy-4-hydroxymandelic and 4-hydroxymandelic acid respectively. A process version for the condensation of the phenol with glyoxylic acid, wherein it was found advisable to add an aqueous solution of glyoxylic acid and part of alkali to a batch of the phenol in aqueous alkali, was found to give 77% yield of the mandelic acid based on glyoxylic acid. The oxidation of the mandelic acid could be more suitably carried out at 95°C using 0.51 mol of copper (II) hydroxide for every mole of the mandelic acid in a process where air is simultaneously passed. Taking 3-methoxy-4-hydroxymandelic acid as an example, 88% conversion to vanillin could be obtained. The reaction was found to be second order with respect to the mandelic acid. 相似文献
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A two-dimensional reactor model was established for a packed-bed electrochemical reactor with cooled cathode (PERCC) for producing glyoxylic acid from oxalic acid based on the system's reaction kinetics, mass conservation equation, and the equation of charge conservation in terms of solution-cathode potential to describe the distributions of glyoxylic acid concentration and electrolyte potential in the cathode compartment of the PERCC. The equation for a circulating mixer was also presented to account for the accumulation of glyoxylic acid in the catholyte of a batch electroreduction process. Using the orthogonal collocation approach, the partial differential equations of the model could be converted into sets of algebraic equations and be numerically solved. The effects of operating temperature, conductivity of catholyte, operating cathode potential, and volumetric flow rate of the catholyte on the current efficiency and concentration of glyoxylic acid were simulated and discussed, with emphasis on the current densities generated from main and side reactions. The model was used in a batch operation process and a continuous operation process, with the predicted results being generally in good agreement with the experimental data for both the cases. 相似文献
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研究连续草酸电解还原制备乙醛酸的过程和工艺。采用一膜两室电解面积为10cm×10cm的离子膜电解槽进行连续电解实验,比较了电极材料、阳离子交换膜材料、研究了电解液流量对电流效率的影响以及电流密度、电解温度和电解时间对电解过程的影响。结果表明以铅极板作阴极、钽-铱作阳极板、NF-1型含氟磺酸阳离子交换膜时电解的效果较好,得到的优化电解条件为:电流密度1000A.m-2,电解温度25℃,电解时间4.5h,阴极液和阳极液流量均为2L.min-1。在此条件下的电耗为3038.9kWh.t-1产品,研究结果可为工业化设计提供参考数据。 相似文献
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The effect of chemisorbing water on three catalysts previously evaluated in the acetone condensation reaction has been studied.
The active sites in that reaction are Lewis acid sites present either on the surface of alumina or of nonframework alumina
in zeolites. These sites are poisoned by water and the reaction rate decreases at the pace of the loss of Lewis sites. The
stoichiometry of the poisoning reactions is one water molecule per site on alumina and two water molecules per site on nonframework
alumina.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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固体酸催化合成环己酮甘油缩酮的研究 总被引:3,自引:0,他引:3
研究并比较了HY分子筛、Hβ分子筛、HZSM-5分子筛、酸化蒙脱土、SO42-/Fe2O3和H2SO4/C等固体酸催化甘油和环己酮缩合反应的催化活性。结果表明,Hβ分子筛具有最优的催化活性,以Hβ分子筛为催化剂,研究了催化剂用量、反应物摩尔比、带水剂环己烷用量、反应时间对环己酮转化率的影响,得出最佳反应条件为:催化剂用量为0.2 g/mol环己酮,n(环己酮)∶n(甘油)=1∶1.5,环己烷用量为100 mL/mol环己酮,反应时间1 h。在此条件下环己酮的转化率和主产物2-羟甲基-1,4-二氧杂螺环[4,5]癸烷的选择性分别为99.5%和98.5%。然后应用量子化学方法探讨了酸催化下此反应的反应机理,求取了甘油和环己酮碳正离子反应速率控制步骤的过渡态,并根据频率分析和内禀反应坐标计算对该过渡态的合理性进行了确认,得到该步反应的活化能为120.017 kJ/mol。 相似文献