Kinetics of glycine oxidation by N-bromophthalimide in the presence of sodium dodecyl sulfate

The kinetics of oxidation of glycine by N-bromophthalimide (NBP) were studied in the presence of an anionic surfactant, sodium dodecyl sulfate, in acidic medium at 308 K. The rate of reaction was found to have first-order dependence on [NBP] and fractional-order dependence on [glycine] and [H⁺]. The addition of reduced product of the oxidant had no significant effect on the rate of reaction. Increasing [Hg(OAc)₂] and [Br⁻] increased the rate of reaction, whereas a change in ionic strength (μ) of the medium had no effect on oxidation velocity. The rate of reaction decreased with a decrease in dielectric constant of the medium. HCN was identified as the main oxidation product of the reactions. The various activation parameters have been computed. A suitable mechanism consistent with the experimental findings has been proposed. The index of cooperativity and the micelle binding constant have been calculated.     

相转移催化合成肉桂酸

以苄基三乙基氯化铵为相转移催化剂,K2CO3为催化剂,通过Pinker反应合成了肉桂酸。在回流条件下,以苄基三乙基氯化铵为相转移催化剂时,n(苯甲醛)∶n(乙酸酐)∶n(碳酸钾)∶n(苄基三乙基氯化铵)=1∶3∶1∶0.03,回流90min,肉桂酸的产率可达到78.5%。     

甲苯液相氧化动力学研究

建立了一套甲苯液相空气氧化的连续反应装置,在工业条件下进行了动力学实验研究。在排除氧气、催化剂质量分数等影响因素下,建立了反应动力学模型,并回归得到模型参数。用该模型计算得到的甲苯转化率和实验结果对比,最大误差4.72%,平均误差2.36%。研究结果表明,甲苯转化率受温度和停留时间的影响较大,尤以温度影响更为明显;主产物选择性受温度和停留时间的影响较小,但停留时间延长,会加剧苯甲醛向苯甲酸转化。     

超临界水中乙酸氧化的研究进展

超临界水氧化技术是一种快速彻底降解废水中有机物质的新型处理技术。在超临界水氧化有机物中 ,乙酸被认为是一种中间产物 ,乙酸氧化是反应速率的控制步骤 ,其氧化动力学的研究对反应器设计具有重要意义。大部分研究都集中在动力学参数和反应条件如温度、压力、密度和停留时间上。最近的研究发现加入二氧化锰等催化剂 ,可缓和反应温度、压力条件 ,以达到高效节能的目的。综述了目前在超临界水氧化乙酸动力学方面的研究进展。对连续平推流或间歇反应器中实验数据用幂指数曲线拟合得到的动力学方程表明 ,乙酸氧化为一级反应     

反相高效液相色谱法同时测定生物转化液中苯乙酮和肉桂酸

建立RP-HPLC法测定生物转化液中苯乙酮和肉桂酸的含量。色谱条件:采用Kromasil-100AC18柱(250 mm×4.6 mm,5μm);以甲醇-水-冰醋酸(体积比为75∶25∶0.05)为流动相;流速为1.0 mL/min;检测波长为246 nm;柱温为室温。结果表明,苯乙酮在1.60~320.0μg/mL范围内呈良好线性关系(r=0.999 2);肉桂酸在2.00~400.0μg/mL范围内呈良好线性关系(r=0.999 6)。苯乙酮和肉桂酸的平均回收率分别为100.42%和101.75%,相对标准偏差(RSD)分别为1.3%和1.7%。     

臭氧与2，4-二氯苯氧乙酸的直接反应动力学

随着现代农业的发展,农药大量研制及施用,农药污染日益严重,对农药污染的控制成为环境研究领域努力探索的课题．2,4-D（2,4-二氯苯氧乙酸）是使用较广的除草剂,具有非挥发性和可溶性,自然降解较慢,施用后易淋溶迁移导致地下水或地表水污染．2,4-D及其代谢产物如2,4-二氯苯酚等不仅有生物毒性,还能导致基因伤害,已对人类健康和自然环境构成了明显威胁．     

Kinetics of inhibited oxidation of lipids in the presence of 1-octadecanol and 1-palmitoylglycerol

The kinetics of initiated oxidation of sunflower oil methyl esters at 50°C in the presence of the phenolic inhibitorp-methoxyphenol are investigated. It is established that addition of 0.1 M 1-octadecanol and of 0.1 M 1-palmitoylglycerol leads to a 1.5- or 2.3-fold decrease of the rate constant of chain termination on the inhibitor, which proves the blocking of its effect due to the formation of a complex based on a hydrogen bond. The stronger effect of 1-palmitoylglycerol is explained by the presence of two hydroxyl groups in its molecule.     

Antioxidant activities of six natural phenolics against lipid oxidation induced by Fe2+ or ultraviolet light

The mechanisms and antioxidant activities of six natural phenolics against lipid oxidation induced by ultraviolet (UV) radiation or Fe²⁺ were studied. An oil emulsion was prepared with flax oil and the thiobarbituric acid-reactive substances (TBARS) method was used to determine lipid oxidation. The antioxidant activities of the six phenolics against UV-induced lipid oxidation were as follows: quercetin > rutin = caffeic acid = ferulic acid = sesamol > catechin. The inhibitory concentrations (IC₅₀) showed that the effectiveness of these antioxidants against Fe²⁺-induced lipid oxidation was in the order quercetin (1.7 μM) > rutin (10.3 μM) > catechin (14.9 μM) > sesamol (18.5 μM) > caffeic acid (19 μM) > ferulic acid (>250 μM), and quercetin was more efficient than butylated hydroxytoluene (BHT) (2.9 μM). Quercetin and rutin had absorption maxima at the UV-A (320–380 nm) region, while the other phenolics tested had absorption maxima near (catechin, 278 nm) or at the UV-B (280–320 nm) region. The stoichiometric ratios of quercetin, rutin, catechin, and caffeic acid to Fe²⁺ were 3:1, 2:1, 1:1, and 1:1, respectively. Although free-radical scavenging capability of antioxidants was the most critical, UV absorption and/or Fe²⁺-chelation properties of natural phenolics also contributed significantly to the control of lipid oxidation induced by UV or Fe²⁺ in oil systems.     

Fatty acid composition and oxidation of lipids in Korean catfish

This study determined the lipid content and FA composition of muscle and a mixture of muscle and viscera from Korean catfish as well as lipid oxidation and hydrolysis. Lipid content and FA compositions in Korean catfish, which were purchased every month or two during September 1999–July 2000, were analyzed. Lipid oxidation and hydrolysis were determined as PV, thiobarbituric acid value, and FFA in the muscle and the mixture during storage at 2°C for 12 d and −14°C for 9 wk. Lipid contents of the muscle and the mixture were 3.2 (w/w) and 5.4%, respectively. Oleic acid was the most abundant FA in the catfish lipids, constituting 28.0% (w/w) of total FA in the muscle and 25.6% in the mixture, followed by palmitic acid and linoleic acid, amounting to 20.2 and 12.2%, respectively, in the muscle and 20.2 and 12.5% in the mixture. EPA and DHA were 3.2 and 6.8%, respectively, in the muscle and 3.5 and 8.1% in the mixture. Seasonal variation in lipid contents and FA composition was minimal in catfish. Lipids in minced catfish oxidized and hydrolyzed readily at 2°C. Inclusion of viscera into the muscle increased lipid oxidation and hydrolysis. Frozen storage at −14°C and addition of ascorbic acid both reduced lipid oxidation. Frozen storage retarded lipid hydrolysis in catfish.     

合成实验肉桂酸的改进

用氟化钾作催化剂，对肉桂酸的合成工艺进行了改进研究，最佳反应条件以氟化钾为催化剂，苯甲醛：乙酐=1：2，反应时间1h，反应温度为150-170％，收率可达74．5％，降低了反应温度，缩短了反应时间，提高了产率。     

从肉桂酸生物发酵液中提取苯乙酮的研究

开展了从肉桂酸生物转化合成苯乙酮过程中的发酵液提取苯乙酮的研究,通过比较溶剂萃取法和水蒸汽蒸馏法提取的特点,提出了水蒸汽蒸馏-溶剂萃取偶合法从发酵液提取苯乙酮的提取分离方法。结果表明,用溶剂萃取法时,经过乙酸乙酯和调节pH前处理、环己烷萃取、浓缩等步骤,苯乙酮的萃取得率为89.0%,萃取溶剂使用量为1 mL发酵液需要1 mL有机溶剂(乙酸乙酯与环己烷之和);而用水蒸汽蒸馏-溶剂萃取偶合法萃取得率为92.1%,萃取溶剂使用量为1 mL,发酵液仅需0.1 mL乙酸乙酯。     

无溶剂微波辐射对甲氧基肉桂酸的合成

以对甲氧基苯甲醛为原料，醋酸铵为催化剂，采用微波辐射技术，经Knoevenagel反应，在无溶剂条件下合成了对甲氧基肉桂酸。先用L46(4^4)正交试验法确定了反应较合适的条件，然后用单因素试验法考察了酸醛摩尔比、醋酸铵用量、微波功率和辐射时间对反应的影响，得到反应的最佳条件：n(丙二酸)：n(醋酸铵)：n(醛)=1．2：1．0：1，微波功率400W，辐射时间7min。在此条件下产率为87．8％。产品结构经IR和H^1—NMR确证。     

微波辐射下Perkin反应合成肉桂酸

利用微波辐射在PEG-400活化下用苯甲醛和乙酸酐以Perkin法合成肉桂酸，最佳反应条件为：n(苯甲醛)：n(乙酸酐)：n(碳酸钾)：n(对苯二酚)：n(PEG-400)=1：3：1：0．02：0．02，辐射功率300W，副射时间20min，肉桂酸产率达65．3％。     

苯乙烯合成肉桂酸的研究

采用浸渍法制备了CuCl/γ-Al2O3、CuO/γ-Al2O3和CuCl-CuO/γ-Al2O3催化剂,在其分别与吡啶组成的催化体系中,苯乙烯和四氯化碳发生加成反应,分析了催化剂活化温度、活性组分质量分数、反应温度、反应时间及加料顺序等对加成反应中间体1,3,3,3-四氯丙基苯收率的影响.在对甲苯磺酸-硫酸、Fe2(SO4)3·7H2O和ZnSO4等酸性催化剂存在下,1,3,3,3-四氯丙基苯水解生成肉桂酸,1,3,3,3-四氯丙基苯和肉桂酸的纯度分别可达93.0%和90.0%.     

苯乙烯-四氯化碳合成肉桂酸工业化问题的探讨

传统的肉桂酸制备方法——帕金反应法 ,因反应温度高、能耗多、产率低等缺点而削弱了竞争力。新方案改革了工艺 ,剔除了加成液的水洗、酸洗、干燥工序 ,直接回收四氯化碳 ,中间体直接进入水解 ,回收醋酸后再经一系列处理 ,能一次性地得到合格产品     

肉桂酸生物法合成苯乙酮过程跟踪的定量分析方法

利用肉桂酸和苯乙酮的紫外光谱吸收特性,把肉桂酸生物法合成苯乙酮过程的复杂转化液体系定量分析,通过投影模拟的方法进行简化,建立了一种快速有效的检测转化液中肉桂酸转化率的分析方法。该方法快速有效,并在最大程度上降低了发酵液自身紫外吸收的干扰,其对肉桂酸和苯乙酮的测定的平均标准偏差（RSD）分别为1.02%和1.45%,平均回收率为101.34%和99.94%。     

The electrocatalytic oxidation of ascorbic acid on polyaniline film synthesized in the presence of β-naphthalenesulfonic acid

Polyaniline-β-naphthalenesulfonic acid composite film on platinum electrode surface has been synthesized via the electrochemical polymerization of aniline in the presence of β-naphthalenesulfonic acid (NSA). FT-IR, UV-vis and electrochemical characterization indicate the formation of the doped polyaniline. Further investigations found that the polyaniline (PAN) doped with NSA extended the electroactivity of PAN in neutral and even in alkaline media. The PAN-NSA composite film coated platinum electrodes are shown to be good electrocatalytic surfaces for the oxidation of ascorbic acid (AA) in phosphate buffer solution (PBS) of pH 7.0. The anode peak potential of AA shifts from 0.62 V at bare platinum electrode to 0.34 V at the PAN-NSA composite modified platinum electrode with greatly enhanced current response. A linear calibration graph is obtained over the AA concentration range of 5-60 mM using cyclic voltammetry. The kinetics of the catalytic reaction is investigated using rotating disk electrode (RDE) voltammetry, cyclic voltammetry and chronoamperometry. The results are explained using the theory of electrocatalytic reactions at chemically modified electrodes. The PAN-NSA composite film on the electrode surface shows good reproducibility and stability.     

苯丙烯酸邻菲罗啉铕钇配合物的合成及荧光特性

在乙醇介质中，合成了标题化合物，测定了其组成，红外光谱及荧光光谱，结果表明，羧酸的羟基氧及邻菲罗啉中的氮原子均与稀土离子配位，铕钇配合物的荧光强度值高于铕配合物。     

Inhibition of lipid oxidation by carnosine

The antioxidant activity of carnosine, a β-alanine-histidine dipeptide found in skeletal muscle, was investigated. Carnosine (25 mM) inhibited the catalysis of lipid oxidation by iron, hemoglobin, lipoxidase and singlet oxygen from 35–96% suggesting that the antioxidant mechanism of carnosine is not solely due to metal chelation. Heating the carnosine at 100°C for 15 min had no effect on its ability to inhibit these lipid oxidation catalysts, and the activity of carnosine was not affected over the pH range of 5.1–7.1. Studies using tocopherol-containing liposomes suggest that carnosine and tocopherol do not act synergistically to inhibit lipid oxidation. These data indicate that carnosine has excellent potential for use as a natural antioxidant in processed foods. This paper (90-5-5) is published with the approval of the Director of the University of Kentucky Agricultural Experiment Station.     

有机碱催化Knoevenagal法合成肉桂酸及其工艺优化

本文以苯甲醛和丙二酸为原料,吡啶等有机碱为催化剂,利用Knoevenagal反应合成肉桂酸,从而降低了反应温度,提高了产率和产品纯度,简化了合成工艺。同时,比较和分析了不同弱碱催化剂对肉桂酸合成产率的影响,结果表明吡啶的催化效果最好,并通过正交试验探讨了有机碱催化作用下,不同工艺参数对肉桂酸产率的影响,确定反应的最佳工艺条件为:以吡啶为催化剂,反应物苯甲醛/丙二酸摩尔比取1:3,催化剂用量0.02mol,反应时间为90min,肉桂酸产率可达90%。