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以噻吩为原料,经吡啶溴氢酸溴盐溴化得2-溴噻吩,以新型的绿色溶剂2-甲基四氢呋喃为溶剂制备格氏试剂,再和原甲酸三乙酯加成、水解制得2-噻吩甲醛,最后以双氧水氧化得到2-噻吩甲酸。本方法环境友好,总收率达74%。 相似文献
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以二氯甲烷和四氢呋喃为溶剂,活性炭和三氯化铁为催化剂,用水合肼作为硝基还原剂,将3-硝基-2-(2’-氰基联苯-4-基)甲基]氨基苯甲酸甲酯还原为3-氨基-2-[(2’-氰基联苯-4-基)甲基]氨基苯甲酸甲酯,最后经甲醇精制,收率可达93.22%。 相似文献
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对甲基苯基卤化镁是合成2-氰基-4'-甲基联苯的重要原料,后者是最新一代沙坦类抗高血压药物的关键中间体。价廉的对氯甲苯原料在格氏反应中由于引发困难,影响了对甲基苯基氯化镁格氏试剂的应用。本文以镁粉、对氯甲苯为原料,在无水2-甲基四氢呋喃-四氢呋喃混合溶剂中制备格氏试剂,对影响反应的多种因素进行了研究,确定了最优工艺条件,合成收率达95.4%。与传统工艺方法相比,本文方法降低了装置无水性要求,操作简便,收率较高。该工艺为对甲基苯基卤化镁格氏试剂的生产提供了可行的技术路线,可显著降低2-氰基-4'-甲基联苯的合成成本。 相似文献
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采用气相色谱,建立标准曲线法测定催化加氢反应中2-甲基呋喃和2-甲基四氢呋喃含量。在建立的色谱条件下,催化反应体系中乙醇、2-甲基呋喃和2-甲基四氢呋喃分离较好。2-甲基呋喃和2-甲基四氢呋喃质量分数均不超过21.00%,标准曲线法测定二者的峰面积与质量分数线性关系良好,线性相关系数均大于0.999,回收率95.72%~105.00%,相对标准偏差小于2.10%。建立的标准曲线法分析催化加氢反应中2-甲基呋喃和2-甲基四氢呋喃浓度变化,操作简单,结果准确可靠,是一种便捷的分析方法。 相似文献
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Hongbin Zhao He Tian Yonghong Jin Xuejun Cao 《Journal of Applied Electrochemistry》2010,40(7):1307-1316
7-Ketolithocholic acid was synthesized by indirect electrooxidation of chenodeoxycholic acid using the medium of Br−/Br2. Some important factors such as anode material, solvent, initial concentration of chenodeoxycholic acid, current density,
electrolysis time have been investigated in detail. By comparing the experiment results, it can be concluded that productivity
and current efficiency in the divided electrolytic cell are higher than that in the undivided electrolytic cell. The optimized
process conditions have been found to be: the anode material PbO2/Ti, the solvent acetonitrile, and initial concentration of chenodeoxycholic acid 23.8–31.8 mg/mL, current density 95.2–142.9 A/m2. The current efficiency could reach 85% and the productivity of 7-ketolithocholic acid could reach 83%. The melting point,
IR spectrum, 1H NMR, 13C NMR and EI-MS were used to characterize the product. The analytical results confirm that the product is 7-ketolithocholic
acid. 相似文献
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Min Du Bo Feng Hui An Wenqiang Liu Li Zhang 《Korean Journal of Chemical Engineering》2012,29(3):362-368
Experiments were conducted to study the effect of addition of four weak acids (adipic, suberic, phthalic and sebacic acids)
on the regeneration of three types of CO2-loaded rich solvents (Monoethanolamine (MEA), Diethanolamine (DEA) and Methyldiethanolamine (MDEA)). It was found that CO2 could be released faster and in a larger quantity when the amount of acid added to the solvent was increased while other
desorption conditions were maintained unchanged. Adipic acid appeared to be more effective than phthalic, suberic and sebacic
acids in enhancing solvent regeneration rate. Among the three amines investigated, MEA had the highest CO2 desorption rate, while DEA saved the most energy. The effect of adipic acid residue in the MEA solvent on CO2 absorption was also investigated. The residue acid reduced the absorption capacity of the MEA solvent significantly when
the solvent concentration was low and slightly when the concentration was high. 相似文献
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为改进聚对亚苯基苯并二唑(PBO)纤维复合黏结性能差等缺点,在苯环上引入极性基团羟基进行化学分子结构改性,3,3′-二氨基-4,4′-二羟基联苯盐酸盐(DADHBP·2HCl)是羟基改性PBO的关键单体。以4,4′-二羟基联苯(DHBP)为原料经硝化、还原反应合成得到中间体3,3′-二硝基-4,4′-二羟基联苯(DNDHBP)和羟基改性PBO的单体DADHBP·2HCl,并对其反应条件进行了优化。结果表明:对于硝化反应,以甲苯、冰乙酸的混合液为反应溶剂,n(DHBP)∶n(HNO3)=1∶2,反应温度5℃,反应时间2.5h,收率81.39%,高效液相色谱(HPLC)纯度(质量分数)92.43%;还原反应,n(DNDHBP)∶n(FeSO4·7H2O)=1∶9,乙醇为溶剂,七水合硫酸亚铁为助剂,n(DNDHBP)∶n(N2H4·H2O)=1∶5.5,反应温度78℃,反应时间9h,热过滤,滤饼盐酸精制后得到DADHBP·2HCl,收率67.16%,HPLC纯度(质量分数)98.20%。中间体和产物结构经红外光谱、核磁氢谱和电喷雾质谱表征确认。 相似文献
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Cecilia García-Oliva Almudena Perona ngel Rumbero Pilar Hoyos María J. Herniz 《International journal of molecular sciences》2022,23(4)
Rhamnolipids are becoming an important class of glycolipid biosurfactants. Herein, we describe for the first time the enzymatic synthesis of rhamnose fatty acid esters by the transesterification of rhamnose with fatty acid vinyl esters, using lipase from Pseudomonas stutzeri as a biocatalyst. The use of this lipase allows excellent catalytic activity in the synthesis of 4-O-acylrhamnose (99% conversion and full regioselectivity) after 3 h of reaction using tetrahydrofuran (THF) as the reaction media and an excess of vinyl laurate as the acyl donor. The role of reaction conditions, such as temperature, the substrates molar ratio, organic reaction medium and acyl donor chain-length, was studied. Optimum conditions were found using 35 °C, a molar ratio of 1:3 (rhamnose:acyldonor), solvents with a low logP value, and fatty acids with chain lengths from C4 to C18 as acyl donors. In hydrophilic solvents such as THF and acetone, conversions of up to 99–92% were achieved after 3 h of reaction. In a more sustainable solvent such as 2-methyl-THF (2-MeTHF), high conversions were also obtained (86%). Short and medium chain acyl donors (C4–C10) allowed maximum conversions after 3 h, and long chain acyl donors (C12–C18) required longer reactions (5 h) to get 99% conversions. Furthermore, scaled up reactions are feasible without losing catalytic action and regioselectivity. In order to explain enzyme regioselectivity and its ability to accommodate ester chains of different lengths, homology modelling, docking studies and molecular dynamic simulations were performed to explain the behaviour observed. 相似文献
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《溶剂提取与离子交换》2013,31(4):505-526
Abstract A caustic‐side solvent extraction (CSSX) process was developed to remove Cs from Savannah River Site (SRS) high‐level waste. The CSSX process was verified in a series of flowsheet tests at Argonne National Laboratory (ANL) in a minicontactor (2‐cm centrifugal contactor) using simulant. The CSSX solvent, which was developed at Oak Ridge National Laboratory (ORNL), consists of a calixarene‐crown ether as the extractant, an alkyl aryl polyether as the modifier, trioctylamine as the suppressant, and Isopar®L as the diluent. For Cs removal from the SRS tank waste, the key process goals are that: (1) Cs is removed from the waste with a decontamination factor greater than 40,000 and (2) the recovered Cs is concentrated by a factor of 15 in dilute nitric acid. In the flowsheet verification tests, the objectives were to: (1) prove that these process goals could be met; (2) demonstrate that they could be maintained over a period of several days as the CSSX solvent is recycled; and (3) verify that the process goals could still be met after the solvent composition was adjusted. The change in composition eliminated the possibility that the calixarene‐crown ether could precipitate from the solvent. The process goals were met for each of the verification tests. The results of these tests, which are summarized here, show that the CSSX process is a very effective way to remove Cs from caustic‐side waste. 相似文献
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酶法合成长链不饱和脂肪酸酯 总被引:2,自引:0,他引:2
以固定化南极洲假丝酵母脂肪酶为催化剂合成长链不饱和脂肪酸酯。重点讨论了带水工艺、带水溶剂种类、脂肪酸碳链长度和反应温度等因素对反应的影响。结果表明,固定化南极洲假丝酵母脂肪酶对长链脂肪酸、脂肪醇的酯化反应有很好的催化效果,随脂肪酸碳链长度增加,脂肪酶的催化活力提高;有机溶剂和抽真空都可以带出反应中产生的水,溶剂带水有更好效果;相同反应时间内,反应温度60℃比50℃时有更高脂肪酸转化率;脂肪酶在50℃条件下使用30 h,酶活力与未使用前几乎完全相同。以低沸点石油醚(40~60℃)为带水溶剂,酶用量0.5%,反应温度50~60℃,反应时间6 h,可以得到酸值低于1的不饱和长碳链脂肪酸(C16~C22)油醇酯。 相似文献
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ABSTRACT A robust solvent suitable for extracting cesium from alkaline nitrate media like that of the high-level liquid waste stored at the U.S. Department of Energy Savannah River Site has been developed. The solvent is composed of the cesium extractant calix[4]arene-bis-(tert-octylbenzo-crown-6) (“BOBCalixC6”) at 0.01 M, the modifier l-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (“Cs-7SBT”) at 0.50 M, trioctylamine (“TOA”) at 0.001 M, and the aliphatic diluent Isopar® L. The solvent holds up exceptionally well under various stresses, such as sustained contact with waste simulant and dilute nitric acid; repeated extraction, scrubbing, and stripping cycles; and excessive loading. The behavior of the solvent in batch-equilibrium flowsheet tests conducted at 15, 25, and 45 °C is presented. Flowsheet calculations show that the Savannah River Site requirements for a decontamination factor of 40,000 and a cesium concentration factor of 12 could be met in a 22-stage bank of 25-cm centrifugal contactors at 25 °C with conservative assumptions regarding hydrodynamics and stage efficiency. Exploiting the temperature dependence of extraction and stripping could reduce the number of stages to 18. 相似文献
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At the Whiteshell Nuclear Research Establishment, the solvent used In the flowsheet examined for reprocessing thorium fuels is tri-n-butyl phosphate (TBP)in a mixture of aromatic (diethyl benzene, DEB)and aliphatic (Isopar M, supplied by Esso Chemical Canada Limited7rpar;diluents. Degradation studies described in this report have focused on the effect of exposure of this solvent to nitric acid. A comparative study of the nitric acid degradation of this solvent, with binary mixtures of TBP/lsopar M and TBP/DEB solvents, as well as each of the individual solvent components is described. The behavior of the major degradation products in washes with NaOH, H2o and HNO3, and the metal retention properties of the degraded systems are also examined Zirconium-retaining species were observed in. the nitric acid degraded TBP mixed solvents, but they were not detectable when each of the solvent components was individually degraded. These species appear to be identical to those formed by radiolytic degradation. A reaction mechanism Is proposed to account for their formation. 相似文献