负载稀土元素的固体超强酸催化合成乳酸乙酯

乳酸乙酯具有无毒、溶解性好、不易挥发、有果香味、有可生物降解性等特点，因此它是极具开发价值和应用前景的“绿色溶剂”。目前国内乳酸乙酯生产大多采用传统的硫酸酯化法，它存在设备腐蚀严重、产品质量差、环境污染严重、生产成本高等问题。因此开发无污染、无腐蚀的新型催化剂具有重要的意义。     

精馏法合成乳酸乙酯

精馏法合成乳酸乙酯封孝华余敦寿，刘序章，易吉萍（武汉大学环境科学系武昌４３Ｏ０７２）（武汉大学生命科学院）乳酸乙酯既是优质溶剂￣［２］，又是酒类、饮料等食的添加剂￣［３］，在工业上有广泛用途。我国自８０年代初开始生产乳酸乙醋以来，由于产品销路好，利润...     

绿色反应介质乳酸乙酯在有机合成中的应用研究进展

生物质来源的乳酸乙酯作为一种新型的绿色有机反应介质逐渐受到人们的关注.这一溶剂具有无毒、生物可降解、廉价易得、沸点高、同时对水和多数有机物的优秀互溶性等各种符合理想绿色介质的优点.近几年来,以乳酸乙酯为溶剂成功实现了包括Suzuki偶联反应、Glaser偶联反应以及各类具有生物活性杂环化合物的串联合成等反应.本文结合我们自己的研究工作和兴趣,系统综述了近年来以乳酸乙酯为反应介质的有机合成反应研究进展.     

乳酸乙酯对映体和丙酮酸乙酯混合物的气相色谱分析

运用气相色谱手性固定相在适宜的色谱操作条件下将丙酮酸乙酯和乳酸乙酯手性对映体完全分离。以环戊酮为内标物定量测定了丙酮酸乙酯和乳酸乙酯手性对映体的含量,测试结果的相对误差范围为-1.66%~ 1.23%,回收率范围为97.03%~101.9%;RSD为0.15%~0.86%。该法具有简捷、高效、准确、稳定性强、重复性好及线性范围宽等特点,是一种可以同时定量测定丙酮酸乙酯、R-乳酸乙酯及S-乳酸乙酯含量的方法。     

合成乳酸乙酯精馏残液的分析

合成乳酸乙酯精馏残液的分析张青枝，华国雄，鲁富贵，张深松，赵根锁（河南师范大学化学系新乡４５３００２）（河南省化学研究所郑州）关键词乳酸乙酯，精馏残液，红外光谱，电子轰击质谱采用乳酸、乙醇直接酯化法［１］，有机溶剂共沸法［２］，合成乳酸乙酯收率较低。...     

乳酸乙酯对映体纯度的气相色谱法测定

用气相色谱法(手性毛细管柱)成功地测定了乳酸乙酯的对映体纯度;测定(±)-乳酸乙酯的相对标准偏差为0.13%～0.66%,相对误差为0.045%～4.0%;该法具有高效、高选择性、高灵敏度、操作简便等优点.     

有机相中脂肪酶催化合成乳酸乙酯

 考察了在双底物抑制下脂肪酶催化合成乳酸乙酯,最佳溶剂为叔丁醇,在所选的几种脂肪酶中,固定化于大孔丙烯酸树脂的南极假丝酵母脂肪酶B (Novozym 435)的催化活性最好. 对反应条件进行了优化,当酸醇摩尔比为1∶8, 反应温度60 ℃, 酸浓度0.3 mol/L, 酶浓度45 g/mol, 摇床转速200 r/min时产率达到77%, 脂肪酶Novozym 435重复使用6次后产率仍然可达到60%.     

吸附法提乳酸新工艺的研究

从发酵液中提取分离有机酸是当前生物化工中的一个和课题。目前乳酸的提取分离多采用钙盐沉淀法，不仅流程复杂，成本高，而且ＣａＳＯ４存在污染问题。本文在美国普度大学已有工作的基础上，提出了一个更完善的吸附法提取乳酸新工艺。该工艺用ＰＶＰ树脂直接从发酵液中吸附乳酸，用热水进行解吸，并在发酵结束后用ＨＣｌ酸化处理。与现有乳酸生产工艺相比，该工艺具有流程较短，设备较少、工艺先进，回收率较高等特点。它不仅适用于     

高效液相色谱分析法测定乳酸及其甲酯

乳酸在食品、医药等行业有很长的应用历史。近年来，由于聚乳酸(PLA)的生物可降解性导致乳酸的生产再一次受到重视。其中一种乳酸纯化工艺，对发酵法生产的粗乳酸通过酯化-催化精馏相耦合的工艺进行提纯和精制，生产过程中监控的主要指标是乳酸和乳酸甲酯的含量。高效液相色谱分析有机酸不仅简便快速，而且选择性好、准确度高，已用     

VOSO_4/活性炭上常压催化氧化乳酸乙酯合成丙酮酸乙酯

以氧化改性活性炭为载体,用浸渍法制备了系列VOSO4/活性炭催化剂(VO/ACO).采用FT-IR、XRD、ICP和比表面及孔结构测定等表征了催化剂组成与结构.考察了VO/ACO催化剂在常压分子氧氧化乳酸乙酯中的催化作用.结果表明,氧化活性炭是氧钒催化剂的有效载体,以pH=3的VOSO4溶液浸渍得到的VO-3/ACO催化剂具有优良的催化性能,在二氯乙烷中常压,80℃反应18 h,乳酸乙酯转化完全,丙酮酸乙酯的选择性达95.2%.催化剂重复使用三次后的性能基本保持不变.     

Ethyl lactate mediated thioacetalization of aldehydes at ambient temperature

Dithioacetalization reactions of aldehydes with thiols/thiophenols have been successfully achieved at room temperature by employing the green, bio-based ethyl lactate as the reaction medium. By means of this sustainable approach, a class of dithioacetals has been acquired with high diversity and efficiency.     

Insight into the binary mixture of ethyl lactate+acetonitrile from density,speed of sound and refractive index measurements

Density, sound velocity and refractive index of ethyl lactate + acetonitrile mixtures were measured at five temperatures from 283.15 to 323.15 K. Excess molar volumes, partial molar volumes, thermal expansion coefficients, isentropic compressibility and molar refraction values were calculated. It is concluded that deviations from ideality in this system should be assigned to the ability of the smaller acetonitrile molecules to occupy free volume space of ethyl lactate.     

乳酸丁酯的非均相催化合成

在Ga2 O3负载量为20％,500℃焙烧2h的条件下制备了固体酸催化剂Ga2 O3/SiO2,利用红外光谱分析对催化剂进行了表征.将其用于非均相催化合成乳酸丁酯的反应,考察了催化剂用量、n(正丁醇)∶n(乳酸)、环己烷用量、反应时间和催化剂重复使用性能等因素对酯化率的影响.结果表明,该催化剂催化合成乳酸丁酯的适宜反应...     

Accumulation of methylglyoxal and d‐lactate in Pb‐induced nephrotoxicity in rats

Lead (Pb) is an environmental pollutant associated with several diseases, such as nephrotoxicity. Methylglyoxal (MG) is a reactive dicarbonyl compound formed during glycolysis and reported to increase in kidney damage. Metformin is used as an MG scavenger in the clinic. In this study, we investigated the mechanism of Pb‐induced renal injury and the effect of metformin on Pb‐induced nephrotoxicity. Eighteen Wistar rats were randomly divided into three groups: control, Pb, and Pb + metformin groups. Pb (250 ppm) was administered in drinking water, and 50 mg/kg of metformin was co‐administered orally. After 28 days, the levels of MG and its metabolite d ‐lactate in urine, serum and renal tissues were examined. The elevation of renal MG (56.86 ± 17.47 vs 36.40 ± 5.69, p < 0.01) and urinary d ‐lactate (0.68 ± 0.28 vs 0.32 ± 0.13, p < 0.01) was observed in Pb‐exposed rats compared with those in control rats. After co‐treatment with metformin, these phenomena were attenuated. In the present study, it was demonstrated for the first time that urinary d ‐lactate might serve as the candidate marker for Pb‐induced nephrotoxicity in the clinic, and metformin might be a new therapeutic candidate for Pb poisoning.     

Fibre optic fluorometric enzyme sensors for hydrogen peroxide and lactate,based on horseradish peroxidase and lactate oxidase

An optical biosensor for the determination of hydrogen peroxide based on immobilized horseradish peroxidase is described. The fluorescence of the dimeric product of the enzyme catalysed oxidation of homovanillic acid is utilized to determine the concentration of H₂O₂. The membrane-bound enzyme is attached to a bifurcated fibre bundle permitting excitation and detection of the fluorescence by a fluorometer. The response of the sensor is linear from 1 to 130 M hydrogen peroxide; the coefficient of variation is 3%. The sensor is stable for more than 10 weeks. The operating pH for maximal sensor response is 8.15. This allows the sensor to be used in combination with oxidase reactions producing hydrogen peroxide, as is demonstrated with a co-immobilized lactate oxidase-horseradish peroxidase optode for the determination of L-lactate. The fluorescence intensity of this sensor depends linearly on the concentration of lactate between 3 and 200 M and a throughput of 10 samples per hour is possible. The precision is in the same range as that of the monoenzyme optode. The lifetime of the bienzyme sensor for lactate is considerably shorter than that of the peroxidase sensor; it is limited by the stability of the immobilized lactate oxidase enzyme. The sensor has been applied to the determination of lactate in control serum.     

除草剂中间体R-(+)-2-(4-羟基苯氧基)丙酸酯的不对称合成

报道了一种合成苯氧丙酸类除草剂重要中间体R－（＋）－2－（4－羟基苯氧基）丙酸乙酯（即R－（＋）－HPE）的方法，以L－乳酸为起始原料，先经酯化合成L－乳酸乙酯，再与对甲苯磺酰氯反应制备L－对甲苯磺酰乳酸乙酯，再与对苯二酚综合获得R－（＋）－2－HPE，产品的总收率为72.1%。通过元素分析和红外光谱测定，确定了所合成的R－（＋）－HPE的化学结构和纯度；由旋光度的测定，确定了所合成的R－（＋）－HPE的光学纯度为95.7%。     

Gran电位滴定法测定乳酸环丙沙星

介绍了乳酸环丙沙星测定的Gran电位滴定法。采用Gran线性函数进行电位滴定,经图解外推或线性回归处理求出计量点,可直接用于测定乳酸环丙沙星原料药的含量。该法用于多批原料药的测定,结果与药典法基本一致。     

An HPLC method for the determination of ethacridine lactate in human urine

An HPLC method was developed and validated for the determination of ethacridine lactate in human urine. Solid-phase extraction cartridges were used to extract urine samples. Separation was carried out on a C(18) column maintained at 30 degrees C with methanol-0.05% sodium dodecylsulfonate (70:30, v/v, pH 3) as mobile phase at a flow rate of 1.0 mL/min. Detection was at UV 272 nm. The calibration curve was linear in the concentration range of 4-4000 ng/mL, with linear correlation coefficient r equal to 0.9998. The limit of detection for the assay was 1.1 ng/mL. The within-day accuracy ranged from 94.8 to 101.6% and precision from 2.3 to 5.4%. The between-day accuracy ranged from 96.8 to 102.6% and precision from 4.0 to 5.3%. The absolute recovery was 95.4-101.2%. Urine samples were stable for at least 15 days if stored in the dark at -20 degrees C. This simple and accurate method allows the sensitive determination of ethacridine lactate in human urine. It was successfully applied to assess the urine level of ethacridine lactate in women received intra-amniotic injection.     

Extraction and separation of lactate dehydrogenase inhibitors from Poria cocos (Schw.) Wolf based on a hyphenated technique and in vitro methods

Stroke is one of the most common diseases worldwide. Lactate dehydrogenase inhibitors are widely used in the treatment of ischemic stroke, with natural products considered a promising source of lactate dehydrogenase inhibitors. In this study, ultrafiltration liquid chromatography coupled with mass spectrometry was used for the screening and identification of lactate dehydrogenase inhibitors from Poria cocos . Five lactate dehydrogenase inhibitors were selected: dehydropachymic acid, pachymic acid, dehydrotrametenolic acid, trametenolic acid, and eburicoic acid. The inhibitors were extracted and isolated with purities of 96.75, 98.15, 97.25, 95.46, and 94.88%, respectively, by using a new “hyphenated” strategy of microwave‐assisted extraction coupled with counter‐current chromatography and centrifugal partition chromatography by a two‐phase solvent system of n‐hexane/ethyl acetate/ethanol/water at the volume ratio 0.965:1.000:0.936:0.826 v/v/v/v. The bioactivity of the isolated compounds was assessed using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay in PC12 cells. The results also showed that the hyphenated technique of microwave‐assisted extraction coupled with counter‐current chromatography and centrifugal partition chromatography was an efficient method for the continuous extraction and online isolation of chemical constituents from medicinal herbs. Furthermore, the research route based on the activity screening, extraction, separation, and activity verification of the compounds offered advantages of efficiency, orientation, and objectivity.     

Simultaneous determination of lactate and pyruvate in human sweat using reversed-phase high-performance liquid chromatography: a noninvasive approach

The simultaneous determination of lactate and pyruvate in sweat has been performed using reversed phase high‐performance liquid chromatography (RP‐HPLC) with UV detection at 220 nm. The calibration curves were linear in the investigated range 0.3 ‐ 350 mm of lactate, 0.003‐ 1 mm of pyruvate. The sensitivity was good with a limit of detection of 0.03 mm for lactate and 0.001 mm for pyruvate. Recoveries evaluated for the entire procedure were 102 ± 0.1 and 96 ± 0.1for lactate and pyruvate, respectively. The method was successfully applied to analysis of sweat in 8 athletes at rest (pilocarpine sweating) and during physical exercise. Copyright © 2012 John Wiley & Sons, Ltd.