2-甲基吡啶的槽内式间接电氧化

在质子交换膜为隔膜的电解槽内, 以2-甲基吡啶为原料, 以Cr2O72-/Cr3+为媒质, 采用间接电氧化法研究了合成2-吡啶甲酸的反应条件. 实验结果表明, 硫酸浓度、硫酸铬浓度、 反应温度、2-甲基吡啶浓度和阳极电位对产率、转化率、 选择性和电流效率均有影响. 通过变化规律的研究, 找到了各个影响因素的最佳条件为: 硫酸浓度为6.0 mol/L, 反应温度为60 ℃, 硫酸铬浓度为0.15 mol/L, 2-甲基吡啶浓度为0.1 mol/L, 阳极电位为1.50 V.     

2-甲基吡啶在不同有机物/水混合溶剂中的电氧化研究

通过循环伏安、线性扫描伏安测量和恒电位电解实验, 在以质子交换膜为隔膜的电解槽内, 分别以丙酮、乙腈和2-丁酮3种有机物与水作混合溶剂, 研究了2-甲基吡啶在PbO2电极上的电氧化行为. 与纯水溶剂比较发现, 在丙酮与水混合溶剂中, 2-甲基吡啶电氧化生成2-吡啶甲酸的选择性和电流效率最高, 阳极氧化电流密度也明显提高, 完全可以替代在纯水溶液中进行2-甲基吡啶电氧化反应.     

高效液相色谱法测定吡啶、2-氨基吡啶、2-甲基吡啶和2-吡啶甲酸

建立了以磷酸氢二钾-磷酸盐缓冲溶液中添加甲醇为流动相，以反相高效液相色谱同时测定吡啶、2-氨基吡啶、2-甲基吡啶和2-吡啶甲酸的新方法。在流动相为甲醇-0．1mol／L磷酸氢二钾和磷酸缓冲溶液、pH为6．0的最佳条件下，吡啶、2-氨基吡啶、2-甲基吡啶和2-吡啶甲酸的加标回收率分别为98．2％～102．1％、99．1％～101．3％、97．8％～100．7％和99．1％～102．4％；线性范围分别为20～980、18～913、19～943和18～902mg／L；检出限分别为2．0、1．8、1．9和1．8mg／L。本法可同时测定电氧化2一甲基吡啶过程中电解液。     

重铬酸钾氧化法合成2-吡啶甲酸的研究

研究了以2-甲基吡啶为原料,以重铬酸钾为氧化剂,利用化学氧化法合成2-吡啶甲酸的反应条件.考察了反应温度、反应物2-甲基吡啶的浓度和与重铬酸钾的浓度比例、硫酸浓度和反应时间对产率、转化率及选择性的影响,其产物用红外、元素分析和熔点分析表征.实验表明,最佳反应条件:反应温度105℃,2-甲基吡啶摩尔浓度为0.075mol/L,重铬酸钾与2-甲基吡啶浓度比为2∶1,硫酸浓度为9 mol/L,反应时间为2 h,其转化率可达97.6%,2-吡啶甲酸的色谱产率可达87.7%,选择性为89.8%.     

丙酮-水混合溶剂中3-甲基吡啶的电氧化

在以质子交换膜为隔膜的电解槽内, 通过3-甲基吡啶在PbO2电极上的电氧化研究, 发现在丙酮-水混合溶剂中, 与纯水作溶剂相比, 不仅在相同阳极电位下电流密度大幅度上升, 3-甲基吡啶电氧化生成烟酸的选择性和电流效率也明显提高. 通过循环伏安、极化曲线和恒电位电解实验, 研究了在丙酮-水混合溶剂中3-甲基吡啶的电氧化条件, 并比较了不同条件下的选择性和电流效率.     

表面活性剂对3-甲基吡啶电氧化制取烟酸的影响

研究了在阳极液中加入不同类型和不同浓度表面活性剂对3-甲基吡啶电氧化的影响. 结果表明, 十六烷基三甲基溴化铵、脂肪醇聚氧乙烯醚硫酸钠、十二烷基苯磺酸钠、十二烷基二甲基甜菜碱和山梨醇酐单硬脂酸酯的胶团对3-甲基吡啶电氧化有明显的促进作用. 实验结果还表明, 在低浓度的硫酸为支持电解质阳极液中加入表面活性剂与不加表面活性剂相比, 3-甲基吡啶电氧化制取烟酸的选择性和电流效率明显提高.     

3-甲基吡啶在PbO2-SPE组合电极上的电氧化研究

采用热压法制备PbO₂-SPE组合电极,通过循环伏安和稳态极化曲线测量研究了该电极对3-甲基吡啶电氧化反应的活性.考察了阳极液中有、无液相支持电解质和不同阴极液情况下,电流密度与过电位和过电位与槽压的关系.初步研究了利用PbO₂-SPE组合电极在无液相支持电解质的溶液中进行3-甲基吡啶电氧化制取烟酸的可行性,给出了特定条件下的选择性和电流效率.     

电氧化合成2-吡啶甲酸

以2-甲基吡啶为原料,用电化学方法合成了2-吡啶甲酸.研究了反应温度、硫酸浓度、反应物2-甲基吡啶浓度和阳极电位对选择性和电流效率的影响.结果表明,在最佳反应条件下,以电化学方法合成2-吡啶甲酸的选择性高达95.3%,电流效率可达到45.3%.     

新型吡啶衍生物的合成

以2-甲基吡啶为原料,经氧化、硝化、还原反应合成了重要中间体4-氨基-2-甲基吡啶(3); 3分别经1,4-加成反应、Heck反应及取代反应合成了11个吡啶类化合物(4~14),其中5, 6和8~14为新化合物,其结构经¹H NMR, ¹³C NMR, MS和HR-MS进行表征。     

不同电极材料和不同酸介质对3-甲基吡啶电氧化的影响

在以质子交换膜为隔膜的电解池内,通过3-甲基吡啶在PbO₂/Ti、SnO₂/Ti、石墨和MnO₂/Ti电极上的电氧化研究发现,在硫酸溶液中,PbO₂电极是催化活性最高的工作电极.通过3-甲基吡啶在硫酸、高氯酸、磷酸和乙酸介质中的电氧化研究发现,对于PbO₂电极,硫酸是最适合的介质.利用循环伏安实验和恒电位电解实验,研究了电氧化条件和电催化活性,比较了各种条件下的电流效率和选择性.     

2-甲基吡啶在PbO2-SPE组合电极上的电氧化研究

分别采用热压法和热压-电镀法制备PbO2-SPE组合电极, 通过循环伏安和稳态极化曲线测量, 研究了这两种电极对2-甲基吡啶电氧化反应的电催化活性, 同时考察了工作电极电解液中有、无液相支持电解质电位与电流密度的关系及不同对电极电解液情况下, 电流密度与过电位和过电位与槽压的关系. 通过一般PbO2电极与热压-电镀法PbO2-SPE组合电极在电流密度与过电位和电流密度与槽压变化的比较, 发现热压-电镀法制备的PbO2-SPE组合电极在相同过电位下具有更高的电流密度, 在相同电流密度下具有较低的槽压.     

Host proficiency of N,N′-bis(9-phenyl-9-thioxanthenyl)ethylenediamine for pyridine and the methylpyridine guests – a competition study

N,N′-Bis(9-phenyl-9-thioxanthenyl)ethylenediamine proved to be an extremely efficient host compound for pyridine and the isomeric methylpyridines. Furthermore, this host displayed selective behaviour during equimolar guest competitions, consistently favouring 3-methylpyridine in binary, ternary and quaternary experiments. Selectivity orders were 3-methylpyridine >> 4-methylpyridine > 2-methylpyridine, and 3-methylpyridine > pyridine > 4-methylpyridine > 2-methylpyridine, for equimolar ternary and quaternary solutions, respectively. When guest concentrations in binary competitions were varied, 3-methylpyridine remained the favoured guest, even at low 3-methylpyridine concentrations. Single crystal X-ray diffraction showed that all four complexes were isostructural (monoclinic, P2₁/n) while guests occupy discrete cavities in the crystal. Only 3-methylpyridine experiences (guest methyl)C–H???π(host) and (guest methyl)C–H???H–Ar(host) interactions, explaining the observed affinity of the host for this guest. DSC analyses provided further affirmation for the host preference: endotherm peak temperatures for the guest release processes correlated directly with the selectivity order for the three methylpyridine isomers.     

One-step Synthesis of 5-Ethyl-2-methylpyridine from NH4HCO3 and C2H5OH Under Hydrothermal Condition

A simple one-pot approach to synthesizing 5-ethyl-2-methylpyridine(EMP) was established using NH₄HCO₃ and C₂H₅OH as starting materials and commercial Cu₂O as catalyst and oxidant under hydrothermal condition. Different reaction conditions were researched and the optimal ones were achieved by studying the parameters, that could affect the yield of product and by considering the energy and resource saving. The present study provided an eco-friendly way to obtaining EMP with lower volatility using fewer toxic starting materials.     

An infrared and raman spectroscopic study of metal(II) Di(2-methylpyridine) tetracyanonickelate complexes: Ni(C6H7N)2Ni(CN)4 and Cd(C6H7N)2Ni(CN)4

The results of an infrared and Raman spectroscopic study are reported for two new metal 2-methylpyridine tetracyanonickelate complexes, M(C₆H₇N)₂Ni(CN)₄, M=Ni or Cd. Their structure consists of corrugated polymeric layers of {M-Ni(CN)₄} with 2-methylpyridine molecules bound directly to the metal (M). These complexes can act as host lattices in the formation of inclusion compounds with dioxane guest molecules.     

Electrooxidation of 2-propanol on Pt, Pd and Au in alkaline medium

Pd and Au are investigated as electrocatalysts for 2-propanol oxidation and compared with the conventional catalyst of Pt in alkaline medium. The current density for 2-propanol oxidation on Pd electrode is much higher than that on Pt electrode. The onset potential for 2-propanol oxidation on Pd electrode is more negative compared with that on Pt electrode. The results show that Pd is a good electrocatalyst for 2-propanol oxidation and the activity for the electrooxidation of 2-propanol is higher than Pt and Au in alkaline medium. Pd has higher electrocatalytic activity and better stability for the electrooxidation of 2-propanol. The present study shows a promising choice of Pd as effective electrocatalyst for 2-propanol electrooxidation in alkaline medium.     

Insights into the Oxidation Chemistry of 2‐Hydroxypurine by Electrochemical Methods

The oxidation chemistry of 2‐hydroxypurine has been investigated in phosphate containing supporting electrolytes at pH 1.4–9.8 at a pyrolytic graphite electrode by voltammetric studies, spectral studies, controlled potential electrolysis and related techniques. The kinetics of decay of the UV‐absorbing intermediate generated during electrooxidation was followed spectrophotometrically and the decay occurred in a pseudo‐first‐order reaction. The course of the electrode reaction has been deduced to involve a 6e, 6H⁺ oxidation of 2‐hydroxypurine via the formation of 2, 8‐dihydroxypurine. The electrooxidation of 2‐hydroxypurine has been found to be an EC reaction (electrode reaction followed by chemical reactions) in which charge transfer is followed by competitive chemical reactions. A detailed interpretation of the redox mechanism of 2‐hydroxypurine has been presented.