用对氨基苯酚改性的碳纳米管糊电极同时测定羟胺和苯酚(英文)

A carbon paste electrode that was chemically modified with multiwall carbon nanotubes and p-aminophenol was used as a selective electrochemical sensor for the simultaneous detection of hydroxylamine (HX) and phenol. Cyclic voltammetry, double potential-step chronoamperometry, square wave voltammetry (SWV), and electrochemical impedance spectroscopy were used to investigate the use of p-aminophenol in the carbon nanotubes paste matrixes as a mediator for the electrocatalytic oxidation of HX and phenol in aqueous solution. The coefficient of electron transfer and catalytic reaction rate constant were determined using the electrochemical methods. Under optimized conditions, the electrocatalytic oxidation current peaks for HX and phenol increased linearly with concentration in the range of 0.5-180.0 and 10.0-650.0 μmol/L for HX and phenol, respectively. The detection limits for HX and phenol were 0.15 and 7.1 μmol/L, respectively. The anodic potential peaks of HX and phenol were separated by 0.65 V in SWV. Because of good selectivity and sensitivity, the present method provides a simple method for the selective detection of HX and phenol in practical samples such as water samples.     

One‐Pot Synthesis of Nitriles from Aldehydes and Hydroxylamine Hydrochloride over Silica Gel,Montmorillonites K‐10, and KSF Catalysts in Dry Media Under Microwave Irradiation

Abstract

A rapid and facile one‐pot synthesis of nitriles has been carried out from the corresponding aldehydes and hydroxylamine hydrochloride in the presence of environmentally benign silica gel (84–95%), Mont K‐10 (85–96%), and Mont KSF clay (88–98%) catalysts in dry media under microwave irradiation.     

Flow injection spectrophotometric determination of formaldehyde based on its condensation with hydroxylamine and subsequent redox reaction with iron(III)-ferrozine complex

A flow injection (FI) spectrophotometric method is proposed for the determination of low concentration of formaldehyde (HCHO) in liquid media. It is based on the condensation of HCHO with hydroxylamine sulfate, followed by the reduction reaction of iron(III)-ferrozine complex with the residual hydroxylamine to form a purple iron(II)-ferrozine complex (λ_max = 562 nm). In the first reaction, hydroxylamine decreases proportionally to the concentration of HCHO, and therefore the produced purple iron(II)-ferrozine complex decreases with increasing HCHO (a negative FI peak is obtained). The detection limit (S/N = 3) was 1.6 μg L⁻¹. The method can be applied to the determination of HCHO in industrial wastewater.     

Fe(Ⅲ)-5-Br-PADAP-CTMAB体系间接分光光度法测定盐酸羟胺

在 CTMAB存在下 ,基于盐酸羟胺能定量还原 Fe( )离子为 Fe( )离子 ,利用显色剂 5 - Br- PADAP建立了间接分光光度法测定盐酸羟胺的方法。在 p H3.6的 KHC8H4 O4 - HCl缓冲溶液中 ,Fe( ) - 5 - Br-PADAP络合物的最大吸收峰位于 75 0 nm处。盐酸羟胺含量在 0— 35 μg/ 2 5 m L范围内符合比耳定律 ,ε=2 .4 0× 10 4 L·mol-1·cm-1。本方法用于盐酸羟胺 (工业品 )的测定 ,结果令人满意。     

Novel synthetic route of aryl-aminopyrazine

We report a novel synthetic route of aryl-aminopyrazine through a new cyclization reaction by using a hydroxylamine. Starting from Boc-glycine and aminonitrile, the aminopyrazine ring was prepared in several steps. After trifluoromethane sulfonylation of the aminopyrazinone, the resultant triflate was subjected to Suzuki-Miyaura coupling reaction with aryl boronic acid to afford coelenteramine.     

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.     

硫酸羟胺及亚硝酸钠对高碳钢表面锌系磷化涂层的组织和摩擦性能的影响

研究了在锌系磷化液中添加环保型促进剂-硫酸羟胺与常规促进剂-亚硝酸钠以便在高碳钢表面形成锌系磷化涂层．用X射线衍射分析了磷化涂层的相结构的变化,结果发现,形成的磷化膜主要由Zn₃Fe(PO₄)₂·4H₂O(H膜)和Zn₂Fe(PO₄)₂·4H₂O(P膜)组 成．运用扫描电镜分析了磷化涂层的显微组织与磷化时间之间的变化规律．四球摩擦实验结果表明,与亚硝酸钠相比,在锌系磷化液中添加硫酸羟胺能有效降低润滑后的磷化涂层的摩擦系数．     

Facile synthesis of 3-aryl/alkylamino 5-aryl/alkyl 1,2,4-oxadiazoles from acylthiourea

Facile and selective synthesis of 3-aryl/alkylamino 5-aryl/alkyl 1,2,4-oxadiazoles starting from N-acylthioureas has been demonstrated. The regio-selectivity is achieved by simply selecting an appropriate base used for the generation of hydroxyl amine from the corresponding hydrochloride salt. This method also avoids the use of toxic cyanogen bromide. The structure of the synthesized oxadiazoles has been resolved by tandem mass spectral studies.     

Kinetic speciation of BCR reference materials

The accurate study of heavy metal speciation is important in environmental monitoring. There has been much work developing various operationally defined speciation methods for soil and sediment, but there is a need to compare the different approaches by evaluating them for the same sample. In this article, a kinetic method was applied for the heavy metal speciation of the two BCR reference materials, CRM601 and BCR701, which have been specifically developed as materials to evaluate the validated BCR three-step sequential extraction method. When EDTA was used as an extractant, 81.0% of Cd, 68.0% of Cu, 21.5% of Ni, 80.3% of Pb and 71.9% of Zn was extracted from CRM601. For BCR701, the removal ratios were 92.0, 52.3, 18.7, 50.6 and 67.5% with EDTA and 95.7, 25.2, 20.0, 52.4 and 68.5% with hydroxylamine hydrochloride as an extractant, for Cd, Cu, Ni, Pb and Zn respectively. A two-component kinetic model was applied to the extraction curve and the extractable metals were readily classified into two categories, namely, labile fraction and non-labile fractions. The rate constants obtained from the regression model were found to be useful in quantifying the lability of an element. The rate constants obtained from the labile fractions in BCR701 were higher than that of obtained from CRM601, which indicated the high lability of metals in BCR701. When compared with the sequential extraction data, it seemed that the lability of an element was positively correlated to the first step extraction fraction.     

A modular approach to α,β-unsaturated N-aryl ketonitrones

A modular approach to α,β-unsaturated N-aryl ketonitrones has been developed. Specifically, condensation of anilines and enals followed by alkylation of the resulting α,β-unsaturated imines provided N-allyl anilines, which were subjected to oxidation with Oxone® to form α,β-unsaturated N-aryl ketonitrones. This modular approach is general and provides rapid access to diversely substituted α,β-unsaturated N-aryl ketonitrones with a single purification step in good yields.