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过氧化氢氧化合成丙酮酸乙酯 总被引:1,自引:0,他引:1
本文从乳酸乙酯出发 ,通过过氧化氢氧化来制备丙酮酸乙酯[1] ,研究了溶剂三氯甲烷用量、乳酸乙酯与氧化剂比例以及反应时间对反应结果的影响。选择了最佳条件 ,得率可达 76 %以上。 相似文献
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为了提高电解银催化剂催化乳酸乙酯选择性氧化制丙酮酸乙酯的性能,选用SiO2,α-Al2O3和γ-Al2O3为载体,制备了负载型银基催化剂。系统地考察了催化剂的载体类型、负载量和焙烧温度对反应的影响,并通过X射线衍射(XRD)、紫外可见漫反射(UV-vis DRS)和H2程序升温还原(H2-TPR)等手段对负载型银基催化剂进行了表征。证明了游离的Ag+离子和带正电荷的银团簇Agnδ+是该反应的活性物种,当载体类型为α-Al2O3,银负载量为7.8%,焙烧温度为600℃时得到性能较佳的催化剂。在反应温度为340℃、氧和乳酸乙酯物质的量比为1.4、液时空速(LHSV)为0.6 h-1的条件下,乳酸乙酯的转化率为96.8%,丙酮酸乙酯的选择性达90.7%。经过100 h反应后的催化剂仍具有较高活性,通过原位烧炭可... 相似文献
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以V_2O_5和磷酸为原料,采用有机相法制备负载型钒磷氧(VPO)催化剂,并考察了其在乳酸乙酯氧化合成丙酮酸乙酯反应中的催化性能。结果表明,n(P)∶n(V)=1.4∶1.0,TiO_2为载体制备的VPO/TiO_2最好;合成丙酮酸乙酯的最适宜条件为:n(乙腈)∶n(H_2O_2)∶n(乳酸乙酯)=12∶2∶1,催化剂添加量为10%(以乳酸乙酯质量计),反应温度65℃,反应时间5 h;在该条件下,乳酸乙酯的转化率为85.24%,丙酮酸乙酯的收率可达80.96%。催化剂重复利用5次,丙酮酸乙酯收率仍稳定在70%以上。通过对催化剂进行XRD、FTIR、XPS和钒价态分析,提出了反应机理可能涉及以V4+和V5+动态变化为活性中心的氧化还原循环。 相似文献
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一种高效无污染合成丙酮酸乙酯的新方法 总被引:3,自引:0,他引:3
研究了由次氯酸钠和溴化钠催化氧化乳酸乙酯合成丙酮酸乙酯新工艺,并通过正交试验设计方法。得出最佳实验操作条件;温度为30℃以下,反应时间为8h,溴化钠与乳酸乙酯的摩尔比为1:2,盐酸与溴化钠的摩尔比为1:1.4,不采用光照,并由此得到丙酮酸乙酯最好收率为82.86%(文献值为80.2%)。乳酸乙酯的转化率为100%。 相似文献
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溴代丙酮酸乙酯合成方法的改进 总被引:1,自引:0,他引:1
溴代丙酮酸乙酯是一种重要的化学试剂及中间体。用途较为广泛,可用于染料、杀菌防腐剂等的合成。溴代丙酮酸乙酯的合成方法有3种:1)三步法:以酒石酸为原料,总收率为55%;2)两步法,以乳酸乙酯为原料,总收率为51%;3)一步法,使乳酸乙酯直接与溴化剂溴代丁二酰亚胺反应制取,收率达63.5%。 相似文献
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离子液体催化合成食用香料乳酸乙酯的研究 总被引:1,自引:0,他引:1
以离子液体[HSO3-pmim]HSO4为催化剂,乳酸和乙醇为原料合成乳酸乙酯。通过正交实验考察了影响酯化反应的主要因素,确定最佳合成条件为:[HSO3-pmim]HSO4用量10mL,酸醇摩尔比1.0∶1.5,反应温度110℃,反应时间2.0h,酯化率达96.7%。离子液体易分离回收,可重复使用。 相似文献
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对2-氯乙基乙基醚的合成工艺进行了无溶剂合成改进。以三乙胺为催化剂,乙二醇单乙醚与二氯亚砜反应,产物经饱和碳酸钠溶液碱洗、饱和氯化钠溶液水洗、无水硫酸钠干燥,得2-氯乙基乙基醚,并采用1H-NMR和GC-MS对产物结构进行了表征。采用单因素实验研究了投料摩尔比例、反应温度和反应时间对产物色谱纯度和收率的影响。优化后,投料摩尔比例为n(乙二醇单乙醚):n(二氯亚砜):n(三乙胺)=1.0:1.3:0.3、反应温度为70 ℃、反应时间为4 h。在此工艺下经公斤级中试放大,产品的收率可达90.2%以上、色谱纯度达到99.4%以上、含量达到99.2%以上。 相似文献
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硫酸氢钠催化合成乳酸乙酯的研究 总被引:7,自引:0,他引:7
采用硫酸氢钠为催化剂合成乳酸乙酯。研究表明该催化剂具备价廉易得,催化活性高,能有效提高原料利用率,流程简单,操作方便,减少废液排放等优势。产品总收率达88.3%。 相似文献
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Robert L. Jenkins Nicholas Dummer Xiabao Li Salem M. Bawaked Paul McMorn Richard P. K. Wells Andrew Burrows Christopher J. Kiely Graham J. Hutchings 《Catalysis Letters》2006,110(1-2):135-138
In the enantioselective hydrogenation of ethyl pyruvate using hydroquinidine 4-chlorobenzoate modified Pt/γ-Al2O3 catalyst, the sense of the enantioselectivity is a function of the modifier concentration. At low concentration (S)-ethyl lactate is preferred and at higher concentration (R)-ethyl lactate is formed; the opposite trend is observed with hydroquinine 4-chlorobenzoate. This is the first example where
enantio-inversion is induced solely as a function of the chiral modifier concentration. 相似文献
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The enantioselective hydrogenation of ethyl pyruvate to (R)-ethyl lactate has been studied using gases under supercritical conditions as solvents. The catalyst was a 5 wt% Pt/alumina modified with cinchonidine. In supercritical ethane the reaction time could be reduced by a factor of 3.5 compared to toluene under similar conditions, without any loss in enantioselectivity. A further advantage of ethane is that the enantioselectivity remains high even at high catalyst/reactant ratio, which is interesting in view of a possible application of a continuous fixed-bed reactor for this reaction. A strong catalyst deactivation was observed in supercritical CO2, which is due to the reduction of CO2 on Pt as indicated by FTIR. 相似文献
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Thomas Bürgi Fachri Atamny Axel Knop‐Gericke Michael Hävecker Thomas Schedel‐Niedrig Robert Schlögl Alfons Baiker 《Catalysis Letters》2000,66(3):109-112
The adsorption of ethyl pyruvate on Pt(111) has been studied by in situ XANES measurements in the presence and absence of
hydrogen. Depending on the hydrogen and ethyl pyruvate pressure, the C and O K‐edge spectra exhibit distinctly different angular
dependence. Without hydrogen ethyl pyruvate is oriented preferentially perpendicular to the surface, indicating bonding via
the O lone pairs. In the presence of hydrogen the mean orientation is more tilted towards the surface. Likely, ethyl pyruvate
also interacts with Pt via its π system under these conditions. The observed angle‐dependent shift of the energy of the π*
and σ* resonances indicates the coexistence of differently adsorbed ethyl pyruvate species. The experimental findings demonstrate
the importance of the in situ approach for unraveling the adsorption mode of ethyl pyruvate in the enantioselective hydrogenation
over cinchona‐alkaloid‐modified Pt.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献