Bromination of some aromatic compounds by means of bromine in chlorosulphonic acid medium

Bromination of a series of aromatic compounds is carried out by means of bromine in chlorosulphonic acid medium in the presence of iodine as a halogen carrier. Some compounds are brominated and oxidised, the others are brominated only with brominolysis of the groups present, e.g. -CHO, -COOH, -NO₂ and -CN groups.     

Liquid-chromatographic determination of rate constants for the cellulose-dimethyloldihydroxyethyleneurea reaction

Rates of the MgCl₂-catalyzed reaction between cellulose and 4,5-dihydroxy-1,3-bis(hydroxymethyl)-2-imidazolidinone were measured at 70, 90, and 110°C. The rate constants were determined by curing the resin for various times, extracting the unreacted resin, and determining its concentration by liquid chromatography. The energy of activation was calculated from the rate data. This work confirms the pseudo-first-order behavior of this reaction.     

Polarographic determination of titanium in soap

Conclusion Titanium dioxide can be determined in soaps polarographically by the method described above. It has been found that no maximum suppressor was necessary and that the diffusion current is directly proportional to the concentration and is well defined. The method is adaptable to soaps.     

Polyethyleneglycol catalytic dehydration kinetics in the liquid phase

Eleven representative polyethyleneglycol (25322–68–3) catalytic dehydration reactions have been studied in the liquid phase at atmospheric pressure. The aim of this research is to build a kinetic model representative of the polyethyleneglycol dehydration process. Three types of reaction take place simultaneously in the process: cyclisation, condensation and alcoholysis. Activation energies and frequency factors are given, and the relationships between kinetic parameters and chain length of reactants and products are discussed according to the reaction type.     

Formation of genotoxic dicarbonyl compounds in dietary oils upon oxidation

Dietary oils—tuna, salmon, cod liver, soybean, olive, and corn oils—were treated with accelerated storage conditions (60°C for 3 and 7 d) and a cooking condition (200°C for 1 h). Genotoxic malonaldehyde (MA), glyoxal, and methylglyoxal formed in the oils were analyzed by GC. Salmon oil produced the greatest amount of MA (1070±77.0 ppm of oil) when it was heated at 60°C for 7 d. The highest formation of glyoxal was obtained from salmon oil heated at 60°C for 3 d. More glyoxal was found from salmon and cod liver oils when they were heated for 3 d (12.8±1.10 and 7.07±0.19 ppm, respectively) than for 7d (6.70±0.08 and 5.94±0.38 ppm, respectively), suggesting that glyoxal underwent secondary reactions during a prolonged time. The amount of methyglyoxal formed ranged from 2.03±0.13 (cod liver oil) to 2.89±0.11 ppm (tuna oil) in the fish oils heated at 60°C for 7 d. Among vegetable oils, only olive oil yielded methylglyoxal (0.61±0.03 ppm) under accelerated storage conditions. When oils were treated under cooking conditions, the aldehydes formed were comparable to those formed under accelerated storage conditions. Fish oils produced more MA, glyoxal, and methylglyoxal than did vegetable oils because the fish oils contained higher levels of long-chain PUFA, such as EPA and DHA, than did the vegetable oils. A statistically significant correlation (P<0.05) between the α-tocopherol content and the oxidation parameters was obtained from only MA and fish oils heated at 60°C for 3 d.     

吡啰红B作为电化学探针线扫极谱法测定透明质酸

在pH 3.5的Britton-Robinson(B-R)缓冲溶液中,吡啰红B在-1.01 V(vs.SEE)处有一个灵敏的线性扫描二阶导数极谱还原峰,当加入一定量的透明质酸后,由于此条件下吡啰红B带正电荷,而透明质酸带负电荷,两者之间通过静电引力作用形成一种生物超分子复合物,导致溶液中吡啰哕红B的游离浓度降低,相应的还原峰电流降低而峰电位基本保持不变.优化了结合反应条件和电化学测定条件,考察了常见干扰物质对测定的影响.在最佳实验条件下,还原峰电流的降低值与透明质酸的浓度在30.0～1000. mg/L范围内呈线性关系,线性回归方程为△ip"(nA)=10.42 c(mg//L)-224.69(n=11,r=0.993),将该方法应用于透明质酸模拟样品的测定,结果令人满意.     

大孔强酸性树脂对1,4-丁二醇脱水催化作用的研究

考察了大孔强酸性树脂对1,4 丁二醇脱水制四氢呋喃的催化作用。结果表明,大孔强酸性树脂对1,4 丁二醇脱水制四氢呋喃催化作用明显优于一般强酸性树脂。     

强固体酸催化合成乙二胺的研究

研究了固体酸催化剂的制备工艺 ,采用NH4Cl离子交换后的MOR型分子筛作载体 ,并加入活性氧化铝制备成强固体酸催化剂。采用此催化剂 ,催化氨化单乙醇胺 ,可选择性的得到乙二胺 ,另外生成一定量的哌嗪。较佳的工艺条件为 :反应温度 340℃ ,NH3 /MEA摩尔比为 5 0、NH3 分压为 0 7MPa,单乙醇胺转化率大于 80 % ,乙二胺选择性为 4 8 1% ,哌嗪选择性为 31%     

Application of heteropoly acid catalyst in an inert polymer membrane catalytic reactor in ethanol dehydration

The ethanol dehydration reaction was carried out in an inert membrane catalytic reactor. 12-Tungstophosporic acid as a catalyst and polysulfone as an inert membrane were used in this study. Ethanol conversion and ethylene selectivity were remarkably enhanced in comparison with those in a fixed-bed reactor under the same reaction condition.     

From the century of the rate equation to the century of the rate constants: a revolution in catalytic kinetics and assisted catalyst design

In the past, rate constants were extracted from rate equations obtained by fitting kinetic data. In the future, they will be calculated by computational chemistry or measured by surface science techniques. They will be used for the start-up of a microkinetic analysis in a combinatorial iteration for the development of optimized catalysts.     

Reduction of azo-compounds—I. Polarographic behaviour of some 4-hydroxymonoazo compounds at the dropping mercury electrode

The polarographic behaviour of some monoazo compounds has been studied in aqueous solutions of varying pH. The reduction current in alkaline media is almost half that of the limiting value in acid solution, indicating a change in the mechanism of reduction. A general mechanism for the reduction process in alkaline and acid media is suggested, which includes a rate-determining step involving one electron. The different kinetic parameters for the electrode reaction support the suggested mechanism. The effect of substituents is clarified.     

Further observations on the dicarbonyl compounds formed via autoxidation of methyl linoleate

a-Dicarbonyls isolated from oxidized methyl linoleate and conclusively identified as DNP-osazones³ were glyoxal, methyl glyoxal,a-keto hexanal,a-keto heptanal, anda-keto octanal. Technical Paper No. 2012, Oregon Agricultural Experiment Station.     

强酸性树脂催化合成醋酸甲酯动力学

在釜式反应器中研究了Amberlyst-15强酸性离子交换树脂催化合成醋酸甲酯的反应动力学,考察了搅拌速度、反应温度、催化剂用量等影响因素。结果表明,随着温度的升高,反应速率增大,而反应平衡常数减小;催化剂用量与反应速率常数基本成正比关系。分析并计算得到了酯化反应的动力学参数,建立了反应动力学方程。     

甘油催化脱水制丙烯醛反应的研究进展

介绍了甘油催化脱水制丙烯醛的工艺路线,包括液相法和气相法。重点介绍了近年来甘油催化脱水制丙烯醛催化剂的研究进展。目前研究较多的有分子筛类、氧化物类以及杂多酸类催化剂,综述了各类催化剂在甘油催化脱水制丙烯醛反应中的催化性能,指出提高丙烯醛收率是催化剂开发的关键,不同层级结构沸石是该反应中最有发展潜力的催化剂。     

Monocarbonyl compounds from catalytic decomposition of autoxidized unsaturated fatty acid esters

Monocarbonyl compounds formed by the decomposition of autoxidized triolein, methyl linolenate, and methyl arachidonate were converted into their 2,4-dinitrophenylhydrazone derivatives and analyzed by thin layer and paper chromatographies. From decomposition of autoxidized triolein with acid-washed Fuller’s earth alkanals were the only monocarbonyl products found, whereas, with metal catalysts or heat, 2-alkenals were the primary products. Autoxidized methyl linolenate and methyl arachidonate decomposed with metal catalysts or heat yielded 23–55% of 2,4-alkadienals but minor amounts with acid-washed Fuller’s earth. The differences in distribution of monocarbonyl products were attributed to a selective course of scission of the hydroperoxides that depended upon the conditions of decomposition.     

催化反应液中氨基葡萄糖酸的光度法测定

利用氨基葡萄糖酸在强酸性(pH 1.5)条件下形成内酯,并与羟胺碱-三氯化铁显色体系生成红棕色络合物,建立了氨基葡萄糖酸的分光光度检测方法,给出了线性方程。检测波长为500 nm,在1.0×10-5～9.0×10-5 mol/mL范围内呈现良好的线性关系,平均加标回收率为99.28%,相对标准偏差≤4.91%。该方法操作简单、结果稳定、选择性和灵敏度良好,能成功应用于实际样品的检测。     

Polarographic reduction of some oxazolones at the dropping mercury electrode

The polarographic behaviour of a series of 4-arylidene-2-phenyl-2-oxazolin-5-one derivatives over a wide range of pH is reported and discussed. A mechanism for the electrode process is elucidated and confirmed via isolation and characterisation of electrolysis products.     

强酸性阳离子交换树脂催化合成甲酸辛酯的研究

以甲酸、正辛醇为原料,直接酯化合成甲酸辛酯,研究了反应温度、反应时间、原料配比、带水剂、催化剂用量等对反应的影响。结果表明,合成甲酸辛酯的最佳工艺条件是:反应温度100℃,反应时间30min,甲酸与正辛醇物质的摩尔比为1.2∶1,催化剂用量为0.5g,带水剂环己烷为12.5mL(正辛醇为0.15mol的情况下)。甲酸辛酯的收率达到95.94%。该催化剂具有价廉易得、催化活性好、不腐蚀设备、无环境污染等优点,不经处理可循环使用多次。