微波促L-苯丙氨酸消旋反应研究

介绍了微波促L-苯丙氨酸消旋反应是一种新的可适合于工业化的生产方法，具有对环境友好的优点。使用微波作为热源不仅可加速反应和节约能源，也可提高反应的收率和产品的纯度。本方法确定了在微波辐射下，以1．0mol／L氢氧化钠水溶液替代低级脂肪酸作为反应溶剂，用物质的量比为0．10的水杨醛为催化剂，L-苯丙氨酸可以快速消旋；在此务件下，消旋反应随微波辐射功率的提高而加快，在66％输出功率下反应已接近最大反应速率。从实验中得出微波促L-苯丙氨酸消旋的反应是一级不可逆反应。考察了此消旋反应的影响因素，同时讨论了微波作用下L-苯丙氨酸的消旋反应机理。     

L-丙氨酸甲酯消旋反应改进

对L-丙氨酸甲酯(L-AlaMe)消旋方法进行改进,研究了消旋制备DL-丙氨酸甲酯的条件.结果表明:当以水杨醛为催化剂、强酸性D072离子交换树脂为助催化剂、n(C7H6O2):n(L-AlaMe·HCl)=0.1回流反应时,消旋效果最好.该法可减少环境污染、节约能耗、降低成本,也可拓展到其他旋光性氨基酸酯的消旋反应中去.     

L-谷氨酸的消旋研究及DL-谷氨酸的制备

研究了L-谷氨酸在不同pH、溶剂、温度、反应时间下的消旋过程,并由最佳消旋条件制备DL-谷氨酸。实验结果表明:当乙酸浓度大于95%、以水杨醛为催化剂、温度90℃、n(水杨醛)∶n(谷氨酸)=0.1时,消旋效果最好。     

与环境友好的化学-生物法制备D-精氨酸和L-瓜氨酸

L-精氨酸在水溶液中利用自身所产生的碱性溶液,用n(水杨醛):n(1-精氨酸)=0.1:1的水杨醛为催化剂,L-精氨酸可以快速消旋为DL-精氨酸.后以DL-精氨酸为底物,利用粪链球菌(streptococcus faecalis)精氨酸脱亚胺酶对L-精氨酸的专一脱亚胺作用,同时制备D-精氨酸和L-瓜氨酸,分别以92.3%、94.2%产率获得光学纯的D-精氨酸和L-瓜氨酸.     

L-苯丙氨酯的合成与表征

以L-苯丙氨酸、正丁醇、SOCl2为原料合成L-苯丙氨酸丁酯,L-苯丙氨酸和正辛醇为原料,对甲苯磺酸为催化剂合成L-苯丙氨酸辛酯,产率分别为84%和53%,并对产物进行IR和1H NMR表征。     

两相体系中胰酶拆分DL-苯丙氨酸

将ＤＬ－苯丙氨酸与甲醇酯化得ＤＬ－苯丙氨酸甲酯盐酸盐，在甲苯／水两相体系中用碳酸氢钠中和ＤＬ－苯丙氨酸甲酯盐酸盐得游离ＤＬ－苯丙氨酸甲酯，在甲苯／水两相体系中用胰酶拆分ＤＬ－苯丙氨酸甲酯得到Ｌ－苯丙氨酸和Ｄ－苯丙氨酸甲酯，取得了各步反应的最优条件，并将Ｄ－苯丙氨酸甲酯外消旋得到ＤＬ－苯丙氨酸甲酯继续用于拆分。拆分摩尔收率为６１．４％，所得Ｌ－苯丙氨酸粗品纯度为９２．２％，重结晶后为９８．６％，［α］２５Ｄ＝－３０．５°     

一种改进的由氨基酸酯制备手性氨基醇的新方法

采用NaBH4/CeCl3作为还原体系,在无水甲醇溶剂中,将氨基酸甲酯还原为相应的手性氨基醇。以L-苯丙氨酸甲酯还原制备L-苯丙氨醇的反应为研究对象,考察了催化剂用量、反应温度及时间诸因素对产品收率的影响。结果表明:在n(L-苯丙氨酸甲酯)∶n(CeCl3)=1∶2、反应温度30℃、反应时间2 h的优化条件下,L-苯丙氨醇收率为90.3%。本法有操作简便,收率高等优点,该反应为制备手性氨基醇提供了一种新的有用的合成方法。     

L-苯丙氨醇的制备

以L-苯丙氨酸为原料，经甲酯化后用硼氢化钠作还原剂，在加入氯化锂的条件下还原得到L-苯丙氨醇。还原反应的最佳条件为NaBH4和L-苯丙氨酸甲酯的物质的量比2：1，20℃反应4h，收率达到81％。     

L-苯丙氨酸甲酯化反应(Ⅱ)——L-苯丙氨酸甲酯化反应动力学

根据一般羧酸酯化反应的基元过程和广义酸催化理论 ,假定催化剂氢离子与酰基氧结合的过程为控制步骤 ,导出了一个 L-苯丙氨酸的甲酯化反应动力学方程 ,该方程预测值与实验结果吻合良好。     

D-对羟基苯甘氨酸生产新工艺研究

为了开发一种成本更低、安全可控、环境友好的D-对羟基苯甘氨酸生产工艺,提出了一种以水为溶剂,质量分数为75%的磷酸为拆分剂,水杨醛为消旋催化剂的新方法对DL-对羟基苯甘氨酸进行拆分。考察发现当n(75%磷酸)∶n(DL-对羟基苯甘氨酸)=1.1时拆分效果最好,当n(水杨醛)∶n(L-对羟基苯甘氨酸)=0.20且消旋时间为5 h时最适宜,当反应液p H=6.0时产品收率及质量最佳。该工艺制备的产品质量分数为99.6%,比旋光度为-158.9°,酸吸光值为0.009,碱吸光值为0.010,符合工业化生产要求。     

Fatty methyl ester hydrogenation to fatty alcohol: Reaction inhibition by glycerine and monoglyceride

The present work demonstrates the rate-limiting effect of varying levels of both glycerine and monoglyceride through a series of batch hydrogenations of fatty dodecyl methyl ester, using copper chromite as the catalyst. Reactions were carried out at 3000 psig H₂, 280°C with catalyst levels varying between 1.25 and 1.80%. With increasing contaminant levels of glycerine (0.0, 0.1, 0.5, 5 wt%), conversion of fatty methyl ester to alcohol is correspondingly reduced (95, 89, 80, 2 wt%). On a molar basis of contaminant, monoglyceride equally reduces the conversion of methyl ester to alcohol. In both cases the latent appearance of fatty-fatty ester results from the slower hydrogenation rate. Chemistry is proposed outlining the thermal decomposition of glycerine or glyceride to intermediate components (acetol and acrolein), leading to the generation of propanediols. Experimental studies indicate that diols effectively deactivate the copper chromite catalyst, limiting the rate of fatty methyl ester hydrogenation. Catalyst deactivation is not permanent, suggesting catalyst site blockage by physical adsorption of the polyhydroxyl components. The complete understanding of this interaction holds promise for the development of glycerine/monoglyceride-insensitive catalysts. In addition, a brief overview of methyl ester hydrogenation inhibition effects of some heteroelements, water, and soap is presented.     

离子液体协同催化合成游离氨基酸酯

以L-氨基酸和醇为原料,酸性离子液体辅以少量强酸性阳离子交换树脂作催化剂,直接酯化合成了8种游离的L-氨基酸酯,并用1HNMR对产物进行了表征。通过L-苯丙氨酸正丁酯的合成对离子液体的活性进行了考察,结果表明,所选用的11种离子液体在反应过程中均起到了一定的催化作用和助溶作用。其中,[Hmim][HSO4]效果较好,在重复使用后,显示了较好的稳定性,是氨基酸酯化反应理想的催化剂和助溶剂。     

Process optimization for methyl ester production from waste cooking oil using activated carbon supported potassium fluoride

This paper presents the transesterification of waste cooking palm oil (WCO) using activated carbon supported potassium fluoride catalyst. A central composite rotatable design was used to optimize the effect of molar ratio of methanol to oil, reaction period, catalyst loading and reaction temperature on the transesterification process. The reactor was pressurized up to 10 bar using nitrogen gas. All the variables were found to affect significantly the methyl ester yield where the most effective factors being the amount of catalyst and reaction temperature, followed by methanol to oil ratio. A quadratic polynomial equation was obtained for methyl ester yield by multiple regression analysis using response surface methodology (RSM). The optimum condition for transesterification of WCO to methyl ester was obtained at 3 wt.% amount of catalyst, 175 °C temperature, 8.85 methanol to oil molar ratio and 1 h reaction time. At the optimum condition, the predicted methyl ester yield was 83.00 wt.%. The experimental value was well within the estimated value of the model. The catalyst showed good performance with a high yield of methyl ester and the separation of the catalyst from the liquid mixture is easy.     

聚乙二醇单甲醚脂肪酸酯的碱催化合成及性能

在碱催化下通过聚乙二醇单甲醚（ＰＧＭＥ）和脂肪酸甲酯的酯交换反应合成了ＰＧＭＥ脂肪 酸酯。在酯和醇醚摩尔比为１：１．２．催化剂质量分数为０５％、反应温度１２０℃、反应时间６．５ｈ条 件下,对脂肪酸甲酯的摩尔收率可达９０％。用ＩＲ、~（１３）ＣＮＭＲ对产物结构进行了确证,同时对产物 的表面物性进行了测试。     

The optimization of the ultrasound-assisted base-catalyzed sunflower oil methanolysis by a full factorial design

The ultrasound-assisted sunflower oil methanolysis using KOH as a catalyst was studied at different reaction conditions. A full factorial experiment 3³ with replication was performed. The effects of three reaction variables, methanol-to-oil molar ratio, catalyst loading and the reaction temperature on fatty acid methyl ester yield were evaluated by the analysis of variance and the multiple regression. At the 95% confidence level all three factors and the interaction of the reaction temperature and methanol-to-oil molar ratio were effective on fatty acid methyl ester formation, the most important factor being the catalyst loading. The relationship between the factors and their interactions was modeled by the second-order polynomial equation.     

邻苯二甲酸酐一缩二乙二醇酯的合成

讨论了邻苯二甲酸酐一缩二乙二醇酯的合成工艺,分别以硫酸和对甲基苯磺酸为催化剂合成邻苯二甲酸酐一缩二乙二醇酯。结果表明,对甲基苯磺酸作催化剂的选择性较好,合成邻苯二甲酸酐一缩二乙二醇酯的最佳反应条件为:以对甲基苯磺酸为催化剂,其加入量为一缩二乙二醇质量的1%,反应温度185 ℃,邻苯二甲酸酐和一缩二乙二醇物质的量比为1∶2,反应时间10 h,产品纯度大于98.0%。     

脱氢枞酸蔗糖酯的无溶剂法合成

用精制的脱氢枞酸,在n(硫酸二甲酯)∶n(脱氢枞酸)=1∶1,碳酸钾为催化剂,反应时间为4 h,丙酮回流条件下,得到脱氢枞酸甲酯,产率为75%。脱氢枞酸甲酯与蔗糖在熔融下通过酯交换反应生成脱氢枞酸蔗糖酯,最佳条件为:n(脱氢枞酸甲酯)∶n(蔗糖)=1∶1.5,m(催化剂碳酸钾)∶m(反应物)=0.05∶1,m(乳化剂硬脂肪酸钠)∶m(反应物)=0.1∶1,温度140℃,压强0.5 kPa,反应时间5 h,产率可达32%,测定了其表面张力和乳化能力。临界胶束浓度(CMC)为:9.0×10-3mol/L;此时表面张力为18.42 mN/m。     

超声微波耦合催化合成蔗糖脂肪酸酯

通过超声微波耦合作用,采用无溶剂法制备蔗糖脂肪酸酯,研究催化剂类型、催化剂用量、超声微波功率、酯糖物质的量比和反应温度对蔗糖脂肪酸酯产率的影响。结果表明,超声微波耦合对蔗糖与脂肪酸甲酯的酯交换反应具有良好的促进作用,超声微波耦合作用下,蔗糖和脂肪酸甲酯能够形成较为良好的乳化状态。有机钛催化剂对蔗糖与脂肪酸甲酯的酯交换反应具有极佳的催化性能,与碱催化剂相比,具有用量少和活性高的特点。以钛酸四异丙酯为催化剂,在超声微波耦合体系中,蔗糖脂肪酸酯最高产率可达86.6%,其中,产品单酯含量为92.7%。     

Na/SiO2新型固体碱催化制备生物柴油的研究

以NaOH、正硅酸乙酯和乙醇为原料,经溶胶-凝胶法制备新型固体碱催化剂（Na/SiO₂）,用于催化大豆油与甲醇的酯交换反应制备生物柴油,研究催化剂焙烧温度、n(NaOH)∶n(SiO₂)、n(甲醇)∶n(大豆油)、催化剂用量和反应时间对产率的影响以及催化剂的稳定性。结果表明,固体碱催化剂Na/SiO₂在大豆油与甲醇的酯交换反应中具有较高的催化活性,在催化剂焙烧温度600 ℃、n(NaOH)∶n(SiO₂)=2∶1、n(甲醇)∶n(大豆油)=15∶1、催化剂用量为大豆油质量的7%和反应时间3 h的条件下,脂肪酸甲酯产率可达97.42%,催化剂在稳定性试验中呈现出优良的稳定性。     

Optimization of the reaction parameters for fast pseudo single-phase transesterification of sunflower oil

Transesterification of sunflower oil with methanol was carried out using potassium hydroxide and methoxide as catalysts and MTBE as cosolvent. The aim of this work was to study and optimize the reaction parameters. Chosen parameters were reaction time, catalyst amount and methanol amount (expressed as catalyst-to-oil and methanol-to-oil molar ratios, respectively). The response variables were methyl ester content (ME) and acid value (AV) due to their relationship with the completion and yield reaction, respectively. A factorial plus composite design was developed to carry out the optimization. From this design, several quadratic models have been used to fit the experimental data. All the factors studied had a positive influence on methyl ester content and acid value, except the methanol amount on acid value. For methoxide catalyst, optimum values were 0.235 catalyst to oil molar ratio, 12 methanol to oil molar ratio and 5 min reaching 99 wt.% ME and 0.20 mg KOH/g of AV.