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去甲肾上腺素的光谱电化学研究 总被引:3,自引:0,他引:3
本文用平行入射式光谱电化学方法,测定了去甲肾上腺素的热力学常数E和n值,用n^2+作为自由基稳定剂,讨论了其通过一个电子传递产生半醌自由基中间体的电极反应机理并结合其它电化学方法,证明了NE在电极上以传质扩散为主的准可逆过程。 相似文献
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现场光谱电化学研究的新进展 总被引:3,自引:1,他引:3
电化学以两个凝聚相的荷电界面为其主要研究对象.它广泛地应用于能源、材料等重要科学领域,并对生命科学的发展发挥着重要作用[1,2].为了从分子水平上深化对电化学界面的认识,自七十年代中至八十年代初采用了紫外可见反射、拉曼和红外光谱技术对电化学体系进行现场(in-situ,又称原位)研究,开创了光谱电化学新领域[3,4].光谱电化学在/\十年代发展迅速,推动电化学研究由宏观进入微观、由统计平均深入至分子水平【‘一刀.近年来,随着各种光谱仪器性能的提高以及非线性光谱等新技术的发展,现场光谱电化学研究不断拓宽新领域,… 相似文献
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固/液界面现场光谱电化学的方法包括各种电磁波透射和反射谱(紫外可见、拉曼、红外、X-光等)、磁共振谱(ESR、NMR)以及80年代发展起来的扫描显微谱(STM等)和非线性反射光谱(SHG)等等。固/液界面现场光谱电化学已渗透到固/液界面和电极表面结构,分子水平上的吸脱附和反应机理,电催化和反应动力学等许多研究领域。本文结合文献对上述几个方面以及固/液界面现场光谱电化学的发展方向进行综述。 相似文献
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微机化紫外可见区现场光谱电化学联用测量系统的研制 总被引:1,自引:0,他引:1
本文报道了由微机控制的紫外可见区现场(in situ)光谱电化学联用测量系统的硬件和软件设计。该系统可以测量电化学调制反射光谱,光电流谱和光电容谱,并可实现同一实验体系的同时联合测量,这些功能均由计算机软件完成。该系统已应用于金属、半导体、半导电氧化膜电极/溶液界面行为的研究,得到了一些新的实验结果。 相似文献
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食品中碘的光谱电化学法测定 总被引:4,自引:1,他引:4
本文研究了用光谱电化学法测定食品中的碘,探讨了最佳的测定条件,用于海带,海带表层盐及模拟碘盐中碘的测定,结果满意,回收率高,抗干扰力强,操作快捷,方法简单易行。 相似文献
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探测束偏转光谱电化学 总被引:2,自引:1,他引:2
评述了探测束偏转光与电化学手段相结合作为一种现场的光谱化学技术关研究电极/电解质界面上的应用。分别从实验装置、偏转原理、影响因素及其应用等方面加以论 。共引用文献56篇。 相似文献
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冰醋酸是最重要的有机酸之一,甲酸是冰醋酸中的主要杂质,其含量的多少直接影响冰醋酸的质量。现行国内外标准方法是利用化学方法对冰醋酸中微量的甲酸进行测定,其操作步骤繁琐,费时费力,完成测定工作约需要几个工作日,无法满足贸易结算的快速测定的需要。目前微量甲酸一般采用衍生气相色谱法测定。对甲酸直接定量测定的方法有离子色谱法、气相色谱/质谱法(GC/MS)以及气相色谱/热导检测法(TCD)。本文利用电子捕获检测器(ECD)检测甲酸,避免了衍生化或者标记方法的繁琐及化学法费时费力的缺点,而且其灵敏度远远优于TCD和氢火焰离子化检测器(FID),同时又克服了MS检测器不易定量的缺点,为进口冰醋酸的准确快速测定提供了技术保证。 相似文献
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Shailesh Thakrar Abhay Bavishi Dhairya Bhavsar Shrey Parekh Hardev Vala Ashish Radadiya 《合成通讯》2013,43(22):3269-3278
A new series of 1,4-dihydropyridines bearing a pyrazole moiety in the 4-position were synthesized by a variation of the classical Hantzsch synthesis. The reaction of 1,3-diphenyl-1H-pyrazole-4-carbaldehyde 4a–n with 3-amino crotononitrile in the presence of glacial acetic acid afforded novel 3,5-dicyano-2,6-dimethyl 1,4-dihydropyridines 5a–n. The procedure has short reaction time (15–20 min), easy workup, and good yield of product. The structures of all synthesized compounds were well characterized by mass, infrared, 1H and 13C NMR, and elemental analysis. 相似文献
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A spectroelectrochemical (SEC) assay for uric acid in human urine has been developed that is essentially reagent-free and involves relatively short analysis times of ∼12 min per specimen using a single-point standard addition approach. The SEC method was demonstrated to be selective for uric acid in human urine, avoiding interference through both the usual control parameters (electrolysis potential and measurement wavelength) and the relatively slow kinetics of a post-electrolysis reaction involving the oxidation product. Results from the SEC analysis of a split set of human urine specimens were well correlated to those obtained using a standard high-performance liquid chromatography method, suggesting the feasibility of clinical applications. 相似文献
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《Electroanalysis》2004,16(5):355-359
Water present in undiluted acetic acid can be monitored in situ with Pt and Au microelectrodes using differential pulse and square‐wave voltammetries. Both reduction and oxidation peaks can be obtained. The best quantitative analytical results were obtained for the anodic peak, the Pt microelectrode, and differential pulse voltammetry. The anodic water peak is located at +1.55 V vs. the quasi reference Pt electrode. The voltammetric peak obtained at Pt electrode is apparently not a diffusional one, however, the calibration plot obtained by employing this peak is linear over a wide concentration range, up to 4 mol dm?3. The detection limit has been estimated as 2.3 mM or 0.0043 v/v%. The developed method may be particularly useful, since the Karl Fischer method can not be used to determine water in glacial acetic acid due to the estrification reaction of acetic acid with methanol. A voltammetric wave of undiluted acetic acid could not be obtained in the positive and negative ranges of potential. 相似文献
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Raman spectra of glacial acetic acid from 350 to 3700 cm–1 have been measured at temperatures up to 275°C and at a pressure of 9 MPa. Raman spectra of aqueous solutions of acetic acid from 3.9 to 16 molar have been measured up to 200°C at a pressure of 7 MPa. The spectral region 800 to 1850 cm–1 for both glacial acetic acid and its aqueous solutions have been studied in detail since this region is significantly affected by variations in temperature and concentration. An interpretation of the bands in this spectral region was made with the aid of factor analysis, difference spectroscopy, band resolution techniques and the existing extensive literature. The results suggest that the major equilibrium in glacial acetic acid is between cyclic and linear dimers; however, in aqueous solutions in the concentration range studied, mono- and di-hydrated dimers and cyclic dimers are the predominant species. 相似文献
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In continuation of the work on establishing hydrogen donors in the hydrogen evolution reaction from different acid molecules, cathodic evolution of hydrogen on silver is investigated from solutions of monobasic acetic acid with the aim to establish the origin of reduced hydrogen. Solutions of 0.2 M acetic acid with 0.2 M perchloric acid, neutralized to different pH values by NaOH, are used. The earlier established criterion is used for discerning between two possible hydrogen evolution mechanisms: (1) from dissociated hydrogen ions and (2) from undissociated hydrogen atoms in the molecule. At medium pH values, the undissociated acid molecules participate as hydrogen donors. Rate constants for reactions 1 and 2, evaluated at a potential of –800 mV (SCE), at which the entire pH range can be scanned, are 2.9 × 10–6 and 1.9 × 10–8. 相似文献
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磷酰胺类化合物萃取醋酸 总被引:1,自引:1,他引:1
以6种磷酰胺类化合物为络合剂,正辛醇和加氢煤油为稀释剂,研究了混合溶剂对醋酸稀溶液的萃取相平衡,讨论了磷酰胺类化合物的不同结构对萃取特性的影响.利用红外谱图和31PNMR谱图分析了磷酰胺类化合物萃取醋酸的机理. 相似文献
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运用循环伏安法(CV)和原位紫外-可见光谱电化学法分别研究了邻氨基酚(OAP)和邻苯二胺(OPD)在1 mol/L HCl溶液中单独聚合及二者共聚的电化学过程。OAP和OPD单独聚合及二者共聚时呈现出的不同电化学行为表明OAP和OPD发生了共聚反应。原位紫外-可见光谱研究表明,在共聚过程中,OAP和OPD首先分别被氧化生成其相应的阳离子自由基,然后,OAP和OPD的阳离子自由基与溶液中的OPD和OAP单体或其阳离子自由基发生交互反应生成类苯胺和类吩嗪结构的二聚物/低聚物中间体,生成的中间体继续发生耦合反应生成OAP和OPD的共聚物,呈现出两个波长分别位于477 nm和419 nm处的吸收峰。并用傅立叶变换红外光谱(FT-IR)表征了共聚物的生成。进一步研究发现,OAP和OPD的共聚过程与溶液中OAP和OPD单体的浓度比有关。 相似文献
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运用循环伏安法(CV)和原位紫外-可见光谱电化学法研究了二苯胺(DPA)和邻氨基酚(OAP)在4mol/L H2SO4中单独聚合及二者共聚的电化学过程。DPA和OAP单独聚合及二者共聚时不同的电化学行为表明DPA和OAP之间发生了共聚作用。原位紫外-可见光谱研究表明,在DPA与OAP的共聚过程中,DPA与OAP首先被氧化生成阳离子自由基,然后,两者的阳离子自由基与溶液中的DPA和OAP单体或其自由基发生交互反应产生混合二聚物中间体,其吸收峰位于508 nm处。进一步研究发现,DPA和OAP的共聚过程与溶液中各单体的浓度比有关。 相似文献