Oxa-Pictet-Spengler reaction in water.Synthesis of some(±)-1-aryl-6,7-dimethoxyisochromans

<正>An acid catalyzed oxa-Pictet-Spengler reaction‘on water' leading to the synthesis of a variety of l-aryl-6,7-dimethoxyisochro-mans is described.The aqueous chemistry is a much cleaner,efficient,cheaper and simple method for synthesis.The scope of reactions was extended to thia-Pictet-Spengler reaction to afford the some isothiochromans.     

Electrochemical Behavior of Methanol Influenced by Polyaniline Incorporated with Ferrocenesulfonic-carboxylic Acid

After the synthesis of polyaniline in the presence of ferrocenesulfoniccarboxylic acid, its influence on the electrochemical reaction of methanol was studied. The result indicates that the ferrocenyl in ferrocenesulfoniccarbexylic acid plays an important role in the electrocatalytic oxidation of methanol. CH3OH is adsorbed on PANI-Fc before its electrocatalytic oxidation. When the concentration of methanol is 2 mol/L, it begins to be oxidized. The effect of scan rate on the electrochemical reaction of methanol was also studied and 5 mV/s was favourable. It is another method to insert a metal catalyst in polyaniline without its electrodeposition.     

SULFATION OF PACHYMAN WITH CHLOROSULFONIC ACID USING THE IMPROVED WOLFROM METHOD

High purity polysaccharide of pachyman was isolated from the powder of Poria cocos sclerotium with an yield of 77.8%. The intrinsic viscosity of polysaccharide was found to be 78.95 mL/g in DMSO solution at 25℃. The isolated polysaccharide was reacted with chlorosulfonic acid to obtain pachyman sulfate using the improved Wolfrom method. The results of the orthogonality experiment on the sulfation reaction identified that the effectiveness of the reaction conditions on the degree of sulfation and the value of intrinsic viscosity is in the following order: molar ratio of chlorosulfonic acid to glucoside (3-5) ＞ reaction temperature (60-80℃) ＞ reaction time (1-2 h). The kinetic studies of the pachyman sulfationindicated that the hydrolysis is accompanied with the sulfation process. The decrease in intrinsic viscosity of the sulfated pachyman is proportional to the increase in the degree of sulfation under the mild reaction conditions of ＜ 80℃,chlorosulfonic acid/glucoside mole ratio ＜ 5, and reaction time ＜ 2 h. Beyond the above reaction conditions, excessive loss of -OH group occurs during hydrolysis. The NMR results indicated a complete sulfation on C-6 and a partial sulfation on the C-2 and C-4 of glucoside.     

加热与超声辐照条件下4-(丁二酰亚胺基)-1-丁烷磺酸Brnsted酸催化剂催化吡喃并[4,3-b]吡喃衍生物合成(英文)

4-(Succinimido)-1-butane sulfonic acid was shown to be an efficient and reusable Brnsted acid catalyst for the synthesis of pyrano[4,3-b]pyran derivatives using thermal and ultrasonic conditions. The catalyst was prepared by mixing succinimide and 1,4-butanesultone, which is simpler and safer than the preparation of succinimide sulfonic acid. This method has the advantages of high yield, clean reaction, simple methodology, and short reaction time. The catalyst can be recycled without loss of activity.     

Synthesis of glycerin triacetate over molding zirconia-loaded sulfuric acid catalyst

Zirconia-loaded sulfuric acid (SO24- /ZrO2) catalysts were prepared by impregnation method, molded by punch tablet machine and characterized by X-ray diffraction. SO42- /ZrO2 catalyst was used to obtain glycerol triacetate (GTA) directly from glycerin. The effect of some factors, such as different temperatures of calcination and catalysts molded or not, on the reusable times of catalysts and the yield of GTA were investigated. The optimum reaction conditions were shown as follows: the reaction temperature was 403 K; the reaction time continued for 8 h; the amount of molded catalysts was 5 wt% of glycerin and the molar ratio of glycerin to acetic acid was 1 : 8. The yield of GTA was 97.93% under the optimum condition.     

Trace determination of cobalt ion by using malic acid-malonic acid double substrate oscillating chemical system

A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii （B-Z） oscillating chemical system to form a double substrate one. The results showed that when the concentration of cobalt ion was in the range of 5.27× 10^-8 to 5.37 × 10^-12 mol L^-1, the change of the oscillating period was directly proportional to the negative logarithm of cobalt ion concentration. The sensitivity and precision of the developed method were quite satisfactory. The limit of detection was down to 5.20 × 10^-13 mol L^-1 which was a highest sensitivity found for determination of metal ions using oscillating chemical reaction so far. Some factors influencing the determination were also examined. The method has been successfully used to determine cobalt ion in vitamin B12 injection.     

锗钨酸催化合成水杨酸异戊酯

Isoamyl salicylate was synthesized by using germanotungtic acid as catalyst.The effects of the amaunt of catalyst,the molar ratio of salicycic acid of isoamy l alcohol,the reaction temperature and the reaction time on the yield of ester w ere studied.The optimum reaction conditions were 1.3∶100 (mass ratio) of cataly st to reactants,1∶2.5 (molar ratio) of acid to alcohol,135～153℃ being satisfa ctary reaction temperature and reaction time suitable being 3h.Under such condit ion,the yield of ester was up to 94%.Germanotungtic acid catalyst can be used re peatedly.     

DFT Study on Intermolecular Cleavage Reaction of N-(2-Hydroxyphenyl)-phthalamic Acid

The reaction mechanisms of intermolecular cleavage reaction of N-(2-hydroxyphenyl)-phthalamic acid were studied via the density functional theory(DFT). All geometries of the reactant, transition states, and products were optimized at the B3LYP/6-31G(d, p) level. Vibration analysis was carried out to confirm its identity as transitions’ structure, and the intrinsic reaction coordinate method(IRC) was used to search the minimum energy path. Two possible reaction channels are reported in this article. The calc...     

Kinetics of Reaction of Bromo-epoxy Resin with Oleic Acid catalyzed by Dimethyl benzyl amine

The kinetics of reaction of bromo-epoxy resin with oleic acid in the presence of dimethylbenzylamine catalyst was studied. The reaction is a zero order reaction with respect to oleic acid, first order with respect to epoxy group and 0. 74 order with respect to dimethylbenzylamine. The reaction rate constants at various temperatures and activation energy were determined. The mechanism of this reaction was discussed. Keywords Tetrabromobisphenol-A, Bromo-epoxy resin, Oleic acid kinetics, Reaction mechanism     

Kinetics of Reaction Bisphenol-S Epoxy Resin with Methylacrylic Acid

The reaction kinetics of bisphenol-S epoxy resin with methyl-acrylic acid in the presence of quaternary ammonium salt catalyst was studied. The reaction rate constants at different temperatures were determined. The reaction is first order with respect to epoxy group, zero order with respect to methylacrylic acid and 0.71 order with respect to quaternary ammonium salt catalyst, respectively. The mechanism of this reaction was discussed.     

CuCrO2—CuCr2O4两相共生体系的合成及其对CO—NO反应催化性能的研究

以柠檬酸络合法制备了CuCrO2-CuCr2O4两相共生体系,并对它的催化性能和TPR行为作了考察,结果表明,两相共生对样品的催化性能及TPR行为有显著的影响,两相共生的样品,在Cu/Cr摩尔比为0．7时,具有较高的催化活性,在TPR过程中,具有尖晶石结构的CuCr2O4首先被原成CuCrO2结构,在更高的温度下后者被还原。     

1-萘胺氧化合成1,4-萘醌

研究了在乙酸中,用H2O2氧化1-萘胺合成1,4-萘醌的新方法。 考察了反应温度、反应时间、1-萘胺与H2O2摩尔比、硫酸和H2O2质量分数等因素对产品收率的影响。 得到较优的反应条件为：1-萘胺与H2O2摩尔比为1∶10、H2O2质量分数为5%、硫酸质量分数为45%、反应温度为80 ℃、反应时间为3 h。 在此条件下,1,4-萘醌的收率为52.2%。 该方法具有操作简单、反应时间短和产物易分离等优点。     

水合乙酸锌脱水反应的动力学

用等温热重法和非等温热重法研究了Zn(CH3COO)2 *2H2O的脱水反应.在61.1、 62.8、 66.2、 69.9℃下的等温热重数据,由等转化率下的lnt=E/RT+ln[g(α)/A]进行拟合,确定了活化能的大小;升温速率为10℃/min的非等温热重曲线显示, Zn(CH3COO)2 *2H2O的脱水反应发生在71～102℃间,其数据通过Doyle-Zsako法进行拟合,以线性相关系数为判据,并结合等温热分析拟合结果,得到该脱水反应的积分动力学模式函数g(α)=[-ln(1-α)]2/3、活化能E=100.8 kJ/mol、指前因子ln(A/s-1)=36.09、动力学补偿效应方程为lnA=0.3339E+2.010.     

三氧化二铝含量对Ni／Zr0.4Ce0.6O2—Al2O3催化剂的CH4—CO2重整反应性能影响

采用水热合成法,制备了不同Al2O3含量的Ni/Zr0.4Ce0.6O2-Al2O3催化剂,采用X－射线衍射（XRD）和扩展X光吸收精细结构（EXAFS）,对催化剂样品进行结构表征;考察了Al2O3的加入对催化剂结构和CH4－CO2重整反应活性的影响。结构表征和活性测试表明,催化剂中存在的主要晶相是Zr0.4Ce0.6O2.Al2O3的加入,使催化剂颗粒度变小,镍的分散度提高,并使反应活性有明显改进;而过量Al2O3的加入,却容易导致积炭。     

Factors influencing decomposition of H2O2 over supported Pd catalyst in aqueous medium

Since H₂O₂ decomposition can result in selectivity/yield loss in the direct H₂O₂ synthesis process from H₂ and O₂ over supported Pd catalysts, it is important to have an enhanced understanding about the factors affecting the H₂O₂ decomposition reaction. Herein, detailed studies have been undertaken to investigate the influence of different factors, such as (a) nature and concentration of acid in reaction medium, (b) nature and concentration of halide in presence and absence of acid in reaction medium, (c) pretreatment procedures and (d) catalyst modification by incorporation of different halides, on the H₂O₂ decomposition reaction over a 5% Pd/C catalyst in aqueous medium at 25 °C. This study has shown that the H₂O₂ decomposition activity is profoundly influenced by all the above factors. The effectiveness of the acids in suppressing the H₂O₂ decomposition activity decreased in the following order: hydroiodic acid > hydrobromic acid > hydrochloric acid  acetic acid > phosphoric acid > sulfuric acid > perchloric acid. The ability of the acid to decrease the H₂O₂ decomposition activity was found to very strongly depend on the nature of its associated anion. Halides, such as iodide, bromide and chloride were particularly effective in suppressing the H₂O₂ decomposition activity. Oxidation pretreatment of the catalyst was found to strongly suppress its H₂O₂ decomposition activity, while a reduction treatment was found to promote its activity. A gradual decrease in the H₂O₂ decomposition activity of the catalyst was observed with each successive usage due to in situ sub-surface oxidation of Pd by H₂O₂. Halide incorporation either via the reaction medium or prior catalyst modification had a similar qualitative effect on the H₂O₂ decomposition activity.     

H2NO·自由基和顺-2-丁烯反应机理的理论研究

采用UB3LYP/6-311++G(d,p)//UB3LYP/6-31G(d)方法对H2NO·自由基和顺-2-丁烯反应的势能面进行了研究, 发现了三类共5条可能的反应通道: L4-Ⅰ和L4-Ⅱ(夺氢-加成), L4-Ⅲ和L4-Ⅳ(加成-加成-消除), L4-Ⅴ(加成-加成-消除-催化转换). 动力学分析表明, 该反应为加成-加成-消除过程.     

Dawson型磷钨钼杂多酸的制备及其对H2O2氧化环己酮制己二酸的催化

采用水热法制备了新型H6P2W9Mo9O62.24H2O催化剂,并用UV-Vis、FT-IR和TG-DTA等测试技术对催化剂进行了表征。以微波促进30%过氧化氢氧化环己酮制备己二酸合成反应为探针,考察了催化剂的催化性能。通过正交实验探讨了几种因素对反应的影响,确定了优化工艺条件为:n(环己酮)∶n(过氧化氢)∶n(草酸)∶n(催化剂)=100∶400∶1.25∶0.25,反应温度100℃,微波辐射功率400 W,反应时间3.5 h,己二酸产品的收率达87.33%,纯度可达99.7%。反应结束后,将反应后含催化剂的溶液浓缩至一定浓度,催化产率降低,重复使用5次收率降低为45.89%。     

二苯并呫吨类化合物的环氧化反应研究

研究了二苯并呫吨类化合物的环氧化反应条件, 在室温、碱性条件下, 用廉价的H₂O₂作为环氧化剂对二苯并呫吨类化合物进行环氧化, 产率高达91%～98%, 是一种简便合成环氧二苯并呫吨类化合物的方法.     

基于聚亚甲基蓝-碳纳米管复合膜固载血红蛋白的H2O2生物传感器

采用吸附和电化学聚合修饰方法,制得了聚亚甲基蓝-碳纳米管聚合膜玻碳电极(PMB-MWNTs/GCE),再将血红蛋白(Hb)固定在PMB-MwNTs/GCE表面,制备了稳定的Hb/PMB-MwNTs//GCE的H2O2生物传感器,并用循环伏安法对修饰电极的生物电催化行为进行了表征.研究结果表明,固定在PMB-MWNTs/...     

改性L石催化苯酚羟基化反应的应用

以L沸石为载体,分别采用浸渍法和离子交换法制备了Cu/L催化剂,并应用于苯酚羟基化反应.在苯酚与双氧水摩尔比等于3的条件下详细考察了反应时间、反应温度、L沸石酸碱性以及Cu的负载量和负载方法等因素对反应的影响.结果表明:采用浸渍法制备的催化剂比离子交换法制备的催化剂具有更高的活性,而且增加催化剂酸量或者升高反应温度均有利于提高苯酚转化.在最佳反应条件下,反应2h苯酚转化率为24.0%,苯二酚选择性为71.4%,其中n(邻苯二酚)/n(对苯二酚)为1.22.