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1.
催化动力学电位法测定痕量亚硝酸根   总被引:12,自引:0,他引:12  
基于稀硫酸介质中,亚硝酸根对溴酸钾氧化碘化钾有催化作用,用碘离子选择电跟踪I^-,建立了测定痕量亚硝酸根的催化动力学电位法。在适宜条件下,该指示反应为一级反应,反应速度可用电位的变化(ΔE)表示。当时间固定时,ΔE与亚硝酸根浓度在0-0.12mg/L范围内呈线性关系,检出限为2.0μg/L。该法用于水样中痕量亚硝酸根的测定,结果满意。  相似文献   

2.
基于在硫酸介质中,亚硝酸根对高碘酸钾氧化酚藏花红褪色反应具有较强的催化作用,建立了测定痕量亚硝酸根的催化动力学光度法。线性范围为0.12~1.22mg/L,相关系数为0.9990,检出限为0.016mg/L。用于食品中痕量亚硝酸根的测定,测定结果的相对标准偏差为2、6%~4.2%,回收率为97%.103%。  相似文献   

3.
研究了盐酸介质中,痕量亚硝酸根催化溴酸钾氧化中性红褪色反应及其动力学条件,建立了催化动力学光度法测定痕量亚硝酸根的新方法,NO^-2的测定线性范围为1-7μg/25ml,检出限为1.5*10^-8g.ml^-1。用于化学试剂及唾液中痕量NO^-2的测定,结果满意。  相似文献   

4.
动力学催化光度法测定痕量亚硝酸根   总被引:27,自引:0,他引:27  
刘长增 《分析化学》2000,28(11):1362-1365
磷酸和棉红在100℃下反应生成天蓝色物质(λmax=675nm),该物质在痕量亚硝酸根的催化下被KBrO3氧化褪色,研究了反应的条件,测定了动力学参数,建立了测定痕量亚硝酸根的方法,方法检出限是4*10^-10g/mL,测定范围是0.40-20.00μg/L,用于水体中痕量亚硝酸根的测定,结果满意。  相似文献   

5.
催化光度法测定水中痕量亚硝酸根   总被引:18,自引:0,他引:18  
利用在硫酸介质中亚硝酸根催化溴酸钾氧化吖啶橙的褪色反应 ,建立了测定痕量亚硝酸根的新方法。方法检出限为 7.6× 1 0 -8mol/ L,线性范围 0~1 .1 2× 1 0 -6mol/ L。本法可用于测定雨水和自来水中的痕量亚硝酸根  相似文献   

6.
溴酸钾氧化吡罗红G催化动力学光度法测定痕量NO2^—   总被引:3,自引:0,他引:3  
研究了在磷酸介质中亚硝酸根催化溴酸钾氧化吡罗红G而使褪色,建立了催化动力学光度法测定痕量亚硝酸根的新方法,测定范围为0.2-20μg/mL,检出限为0.2ng/ml,用于食品和水样中的亚硝酸根测定获得满意结果。  相似文献   

7.
溴酸钾氧化亮绿SF催化光度法测定痕量亚硝酸根   总被引:30,自引:3,他引:27  
鲍所言  王彤立 《分析化学》1995,23(2):191-193
本文基于亚硝酸根对溴酸钾氧化亮绿SF而使其褪色所起的催化作用,建立了高灵敏度催化吸光光度法测定痕量亚硝酸根的新方法,测定范围为0.05-20ng/ml,用于不同水样中亚硝酸根的测定,获得了满意结果。  相似文献   

8.
溴酸钾氧化酸性品红催化光度法测定亚硝酸根   总被引:9,自引:2,他引:7  
研究了在强酸介质中亚硝酸根催化溴钾氧化酸性品红的褪色反应及其动力学条件,建立了高灵敏测定痕量亚硝酸根的新催化光度法。方法灵敏度为3.7×10^-11g/cm^2亚硝酸态氮,线性范围为0.06-0.42μg/10mL,用于测定唾液及硝钾中亚硝酸根。  相似文献   

9.
表面活性剂增敏催化光度法测定痕量亚硝酸根   总被引:12,自引:0,他引:12  
张爱梅  王术皓  崔慧 《分析化学》2001,29(2):202-204
基于稀磷酸介质中,溴化十六烷基吡啶对亚硝酸根催化溴酸钾氧化吡罗红B褪色反应的增敏作用,建立了测定亚硝酸根的表面活性剂增敏催化动力学光度法。加入溴化十六烷基吡啶,灵敏度增大2.2倍。测量亚硝酸根的线性范围为0.005-0.15 mg/L,检出限为0.004/L。用于水及蔬菜中痕量亚硝酸根的测定,结果满意。  相似文献   

10.
本根据亚硝酸根与对氨基苯磺酸、H酸在酸性介质中进行的重氮偶联反应,提出了一个测定痕量亚硝酸根的分光光度新体系。最大吸收波长为520nm摩尔吸光系数为3.1× 10^4L/mol.cm亚硝酸根浓度在0-1.2μg/mL范围内符合比耳定律。用于水样中亚硝酸根的分析,测定结果与经典的α-萘胺法一致。  相似文献   

11.
In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.  相似文献   

12.
Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.  相似文献   

13.
KMnO4-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.  相似文献   

14.
The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.  相似文献   

15.
A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.  相似文献   

16.
The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp3)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp2)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp2)?H and aliphatic 1,5- and 1,6-C(sp3)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp3)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp2)?H insertion.  相似文献   

17.
The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.  相似文献   

18.
N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).  相似文献   

19.
An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.  相似文献   

20.
An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y1 and Y2. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.  相似文献   

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