TiCl3 catalyzed one-pot protocol for the conversion of aldehydes into 5-substituted 1H-tetrazole

An efficient protocol has been explored for the one-pot synthesis of tetrazole derivatives with wide functional group compatibility in moderate to very high yields starting from aliphatic and aromatic substituted aldehydes. The reaction proceeds via non-isolated oxime and nitrile intermediates. The structures of the products were confirmed by IR and NMR spectroscopy. A plausible reaction mechanism is also provided.     

Reactions of 3-(polyfluoroacyl)chromones with hydroxylamine. The first synthesis of 3-cyano-2-(polyfluoroalkyl)chromones

Reaction of 3-(polyfluoroacyl)chromones with hydroxylamine proceeds via nucleophilic 1,4-addition followed by opening of the pyrone ring and subsequent cyclization to 4-(polyfluoroalkyl)-4H-chromeno[3,4-d]isoxazol-4-ols in good yields. On treatment with trifluoroacetic acid, the isoxazole ring of this annulated heterocyclic system opens to give 3-cyano-2-(polyfluoroalkyl)chromones. Reaction of 3-(polyfluoroacyl)chromones with hydroxylamine hydrochloride occurs only at the carbonyl carbon atom connected to the R^F group to give the corresponding oximes in low yields.     

Enhancement of the analytical properties and catalytic activity of a nickel hexacyanoferrate modified carbon ceramic electrode prepared by two-step sol-gel technique: application to amperometric detection of hydrazine and hydroxyl amine

The electroless sol-gel technique was used for the construction of nickel hexacyanoferrat (NiHCF) modified carbon composite electrodes (CCEs).This involves two steps: formation of a carbon ceramic electrode fabricated by nickel powder and then immersing the electrode into a sodium- hexacyanoferate solution for the immobilization of NiHCF films. The cyclic voltammety of the resulting modified CCEs prepared under optimum conditions, shows a well defined surface redox couple due to the [Ni^IIFe^III/II(CN)₆]^−2/−1 system. The effect of different alkali metal cations in supporting electrolyte on the behavior of the modified electrode were studied. The charge transfer coefficient (α) and charge transfer rate constant (k_s) for modified films were calculated. Hydrazine and hydroxylamine have been chosen as a model to elucidate the electocatalytic ability and analytical parameters of NiHCF modified CCE prepared by one and two-step sol-gel techniques and these compounds determined amperometically at the surface of modified electrodes. The latter shows a good electocatalytic activity towards the oxidation of hydrazine and hydroxylamine in the pH range 3-8 in comparison with CCEs modified by homogeneous mixture of graphite powder, Ni(NO₃)₂ and Na₂[Fe(CN)₆], (one-step sol-gel technique). Furthermore, the catalytic rate constant, linear dynamic range, limit of detection, and sensitivity for hydrazine and hydroxylamine detections were evaluated and compared with CCEs prepared with one-step sol-gel method. The modified CCEs containing NiHCF shows good repeatability, short response time, t 90%<3 s, long term stability (3 months) and excellent catalytic activity. Furthermore, the method of preparation is rapid and simple and the modified electrodes are renewed by simple mechanical polishing and immersing in [Na₃Fe(CN]₆] solution.     

Sulfated polyborate catalyzed expeditious and efficient three-component synthesis of 3-methyl-4-(hetero)arylmethylene isoxazole-5(4H)-ones

A rapid and highly efficient methodology for the synthesis of 3-methyl-4-(hetero)arylmethylene isoxazole-5(4H)-ones has been developed using sulfated polyborate as a catalyst. The multicomponent reaction of an aromatic/heterocyclic aldehyde, hydroxylamine hydrochloride, and ethyl acetoacetate under a solvent free condition at 80 °C is described. This protocol has promising features for the reaction response such as shorter reaction time, easy work-up, ease of separation of pure product with high yields and simplicity in the experimental procedure. The products have been obtained in high yields (80–90%) and convenient reaction time (15–30 min). The method is operationally simple and eco-friendly.     

比色法测定蒙药铜灰体系中产生的*OH自由基

根据细胞色素C的氧化特性,采用比色法测定蒙药铜灰体系中产生的·OH自由基。实验证明,以盐酸羟胺为还原剂,在磷酸二氢钾缓冲溶液中测定,效果较好。该体系不受β-胡萝卜素的抑制,仅受硫脲的抑制,说明蒙药铜灰可作为筛选抗·OH自由基的消除剂,并具有“燥脓、清肺、肝之热”等功能。     

粘土中游离氧化铁的分离及其测定

研究了盐酸羟胺-草酸-草酸铵体系提取粘土中游离氧化铁及其测量,试验表明,用此体系提取拈土中的游离氧化铁,其测量结果与DCB法一致,而提取及测量所需的时间却较前者短。相对标准偏差RSD≤2．0％。     

种子法制备金掺杂二氧化硅气凝胶

 采用羟胺种子法合成了金掺杂二氧化硅气凝胶。采用紫外 可见光分光光度计研究了还原过程中体系的变化情况。使用透射电镜（TEM）研究了气凝胶的微观结构,气凝胶的比表面积和孔径分布由BET-BJH方法测试。结果表明通过种子法可以制备金掺杂质量分数0.01%~1.00%,密度25～50 mg／cm³,比表面积达800 m²/g以上的SiO₂气凝胶样品。     

羟胺在碳纳米管修饰玻碳电极上的电催化还原及电化学动力学性质研究

研究了羟胺在碳纳米管修饰玻碳电极(CNT/GC)上的电化学行为。研究结果表明,碳纳米管对羟胺的电化学行为有良好的电催化作用,在-0.62 V有一还原峰,是羟胺获得2个电子还原为铵所形成,同时测定了该电化学过程的动力学参数:电子转移数n为2,电子转移系数α为0.287,电极反应速率常数k为1.35×10-3cm/s。     

萘(苯)双十四烷基双磺酸钠Gemini表面活性剂合成及性能研究

Gemini表面活性剂因其特殊的分子结构,使它在降低表面张力的效率与效能,以及起泡性、乳化力、润湿性等方面的性能大大优于传统表面活性剂。由此,Gemini表面活性剂成为近年日用化工及胶体与界面化学领域研究的热点课题之一。目前,Gemini表面活性剂优良的表化性能已被广泛认识,相应的理论研究趋于成熟,但Gemini表面活性剂在实际生产中的应用却不多见,究其原因主要是Gemini表面活性剂大都合成路线长,产品价格高,从而限制了它们的使用。本文拟以α-十四烯烃磺酸为原料,采用“一步法”合成萘（苯）双十四烷基双磺酸钠Gemini表面活性剂,其合成路线和反应条件均与现在生产α-烯烃磺酸钠相似,但成本却低于后者,有望实现高的性能价格比。