数码成像比色法探究反应物浓度对化学反应速率的影响

利用数码成像比色法探究反应物浓度对化学反应速率的影响,采用紫红色溶液互补光"绿"通道的亮度值-时间的曲线变化表征反应物浓度与化学反应速率的关系。同时也利用分光光度计研究反应物浓度与反应速率的关系,测出透光率-时间的曲线变化。从实验结果比较分析,用数码成像比色法探究反应物浓度对化学反应速率的影响是非常简便可行的方法,同时让学生使用随身所带的电子产品开展实验研究,不仅使实验教学具有趣味性和科学性,而且能更好地培养学生的创新潜质。     

铁氧化物/草酸/UVA体系中2-硫醇基苯骈噻唑的光化学降解

 用水热法合成纯γ-FeOOH粉末, 然后分别在250, 320, 420和520 ℃下煅烧得到IO-250等4种铁氧化物. XRD结果表明, 煅烧后得到的IO-250和IO-320为γ-Fe2O3和α-Fe2O3混合相, IO-420和IO-520为纯α-Fe2O3相. N2吸附结果表明, 随煅烧温度升高,铁氧化物比表面积减小. 铁氧化物与草酸悬浮液在紫外光照射下建立了一个铁氧化物/草酸/长波紫外线(UVA)类光Fenton体系,以2-硫醇基苯骈噻唑(MBT)为目标污染物测试了该体系的催化活性. 结果表明, 该体系能有效降解MBT, 不同铁氧化物组成的体系光化学活性依次为IO-320＞IO-250＞IO-420＞IO-520＞γ-FeOOH. 铁氧化物剂量和草酸的初始浓度显著影响体系的光化学活性,不同铁氧化物最佳剂量不同; 草酸能显著促进MBT光化学降解, 在各体系中其最佳浓度均为1.0 mmol/L. 反应过程中Fe2+和Fe3+的浓度及溶液pH值的变化均与铁氧化物的种类和草酸的初始浓度有关.     

N8-芳基取代4-氨基-6-氯-7(8H)-蝶啶酮的合成

通过N4-芳基取代4,5,6-三氨基嘧啶与草酸二水合物环合, 得到N8-芳基取代4-氨基-5,8二氢-6,7-蝶啶二酮, 再经氯代, 得到新型N8-芳基取代4-氨基-6-氯-7(8H)-蝶啶酮, 用红外光谱、核磁共振氢谱、核磁共振碳谱、质谱和元素分析确证了其结构. 用X-ray单晶衍射测定了4-氨基-6-氯-8-对甲苯基-7(8H)-蝶啶酮(3a)的晶体结构, 证明了环合反应的区域选择性.     

Effect of span 20 concentration on oxalic acid production from post-refining fatty acids by Aspergillus niger XP

Submerged fermentation experiments were carried out to study the stimulating effects of the surfactant Span 20 on the growth of Aspergillus niger XP mutant and oxalic acid production from the post-refining fatty acids. Span 20 concentration of 0.75 g dm⁻³ was found to be the most suitable for oxalic acid production from fatty acids. Using this dose and a fermentation medium containing 30 g dm⁻³ of post-refining fatty acids, the oxalic acid production, oxalate yield, and overall oxalate productivity were the highest. Presented at the 33rd International Conference of the Slovak Society of Chemical Engineering, Tatranské Matliare, 22–26 May 2006.     

草酰胺配体的微波合成

在微波辐照下, 分别由苯胺、取代苯胺和草酸通过无溶剂法反应, 合成出N,N′-二(苯基)草酸二酰胺和N,N′-二(取代苯基)草酸二酰胺, 利用¹H NMR, MS和元素分析对其结构进行了表征. 研究表明, 增加辐照功率选择合适的辐照时间有利于产物收率的提高, 甲基或氯单取代的苯胺得率高于苯胺, 增加固液两相的接触面积可大大提高产物的收率.     

17-次乙二氧基-3-甲氧基-雌甾-2,5(10)-二烯-11β-醇用硅胶支持的草酸试剂选择性水解

以3-甲氧基一雌甾-1,3,5(10)-三烯衍生物,经Birch还原所得的3-甲氧基-雌甾-2,5(10)-二烯,是合成各种19-去甲甾体药物的重要前体,在甾体有机合成中有重要意义。在强酸条件下,水解3-甲基烯醇醚,将发生5(10)-双键移位,得到相应的共轭4-烯-3-酮化合物,同时,分子中的其他对酸敏感的基团会     

Pd-Catalysed Decarbonylation Free Approach to Carbonylative Esterification of 5-HMF to Its Aryl Esters Synthesis Using Aryl Halides and Oxalic Acid as C1 Source

A decarbonylation free, polystyrene-supported, Pd (Pd@PS)-catalysed carbonylative esterification of the hydroxy group of 5-hydroxymethyl furfural (5-HMF) to its corresponding aryl esters has been developed. The use of Pd@PS, oxalic acid as CO source, and aryl halides was first explored for the aryl ester of 5-HMF synthesis. Here, we investigated the vital role of a polystyrene support to avoid the commonly known decarbonylation of 5-HMF. The reaction exhibits vast substrate scope with comparably good yield and catalyst recyclability.     

Syntheses and characterization of three lanthanide(III) complexes containing pyridine-3,5-dicarboxylic acid and oxalic acid ligands

Direct reaction of pyridine-3,5-dicarboxylic acid (H₂PDA) and oxalic acid (H₂ox) with Ln(ClO₄)₃ · nH₂O under hydrothermal conditions gave three 3-D coordination networks, [Ln(PDA)(ox)_0.5(H₂O)₂] · H₂O [Ln = La(1), Nd(2), and Eu(3)]. The complexes were characterized by elemental analysis (EA), X-ray single-crystal diffraction, infrared spectroscopy (IR), and thermogravimetric analysis (TGA). Single crystal X-ray diffractions shows that the compounds are isomorphous and have 3-D framework structures, in which pyridine-3,5-dicarboxylates (PDA^2?) link lanthanides to give 2-D layers, which are further fabricated into a 3-D network via bis-bidentate oxalate bridging. Luminescence of 3 is investigated.     

Electrochemical conversion of carbon dioxide catalysed by benzil

It has been shown it is possible to reduce carbon dioxide electrochemically using benzil as a homogeneous electron transfer agent. It was found that oxalic acid is the basic product formed during the electrochemical reduction of carbon dioxide. __________ Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 42, No. 1, pp. 29–32, January–February, 2006.     

Hydrolysis Rates of TMOS Catalyzed by Oxalic Acid and Stimulated by Ultrasound

A simple calorimetric method was employed to study the kinetics of the hydrolysis of the solventless TMOS-water mixtures, under ultrasound stimulation, as a function of the concentration of oxalic acid. The reaction rates were obtained, in relative units, from the measured thermal peak of the reaction as a non-separated function of both the sonication time and the instantaneous temperature of the medium. For concentrations of oxalic acid below 0.01 M, polycondensation reaction starts before complete hydrolysis. For concentrations of oxalic acid above 0.01 M, hydrolysis is complete and, in addition, the inverse of the time, as measured from the starting of ultrasound action until the maximum hydrolysis heat release, was found to be a reasonable relative measure of the average hydrolysis rate constant. The average hydrolysis rate constant was found to be proportional to the square root of the molar concentration of the oxalic acid. This result is in agreement with the literature if we assume small dissociation degree for the catalyst in such a solventless alkoxyde-water medium.