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281.
The kinetic of the reactions of the recently synthesized Schiff base (PABST) and its complex with Cu(II) (Cu-PABST) with CN− in a 30:70 (v/v) mixture of DMF:water was investigated at pH 6.0 and 10.0, respectively, using multivariate curve resolution alternative least squares (MCR-ALS) method. The effects of different parameters such as volume percent of DMF, pH and surfactants and β-cyclodextrin (β-CD), on observed rate constant of the reactions were investigated. Cetyltrimethylammonium bromide (CTAB) decreased the rate constant of PABST reaction and increased the rate constant of Cu-PABST reaction with CN−. Sodium dodecyl sulfate (SDS) and Triton X-100 decreased the rate constant of both reactions. Also the stability constant for the inclusion complexes of PABST and Cu-PABST, and observed rate constants for the reactions of β-CD-PABST and β-CD-Cu-PABST) with CN− were determined. β-CD decreased the rate constant of PABST reaction with CN− by protecting iminium groups of the Schiff base, while β-CD increased the rate constant of the reaction of Cu-PABST with CN−. 相似文献
282.
Sodio C.N. Hsu Yu-Chen Zheng Min-Yuan Hung 《Journal of organometallic chemistry》2008,693(18):3035-3042
The known complexes [Cp2Fe2(μ-SEt)2(MeCN)2](PF6)2 (1) and Cp2Fe2(μ-SEt)2(CN)2 (2) are prepared to investigate their reactivity. The reaction of complex 2 with equimolar amounts of MeOTf yields a monomethylation product [Cp2Fe2(μ-SEt)2(CN)(CNMe)](OTf) (3). Dimethylation of complex 2 by 2 equiv. MeOTf gives a complex [Cp2Fe2(μ-SEt)2(CNMe)2](OTf)2 (4). Complex 1 containing two labile MeCN ligands reacts with several bidentate phosphine ligands, such as dppm, dppa, and dppf, to afford complexes [Cp2Fe2(μ-SEt)2(dppm)](PF6)2 (5), [Cp2Fe2(μ-SEt)2(dppa)](PF6)2 (6), and [Cp2Fe2(μ-SEt)2(dppf)](PF6)2 (7), respectively. The spectroscopic, electrochemical, and reactivity studies of iron-sulfur core complexes are performed. The structures of complexes 1-7 were confirmed by X-ray crystallography. 相似文献
283.
A new flow injection approach to total weak acid-dissociable (WAD) metal–cyanide complexes is proposed, which eliminates the need of a separation step (such as gas diffusion or pervaporation) prior to the detection. The cornerstone of the new methodology is based on the highly selective flow-injection potentiometric detection (FIPD) system that makes use of thin-layer electroplated silver chalcogenide ion-selective membranes of non-trivial composition and surface morphology: Ag2 + δSe1 − xTex and Ag2 + δSe. An inherent feature of the FIP-detectors is their specific response to the sum of simple CN− + Zn(CN)42− + Cd(CN)42−. For total WAD cyanide determination, ligand exchange (LE) and a newly developed electrochemical pre-treatment procedure for release of the bound cyanide were used. The LE pre-treatment ensures complete recovery only when the sample does not contain Hg(CN)42−. This limitation is overcome by implementing electrochemical pre-treatment which liberates completely the bound WAD cyanide through cathodic reduction of the complexed metal ions. A complete recovery of toxic WAD cyanide is achieved in the concentration range from 156 μg L−1 up to 13 mg L−1. A three-step protocol for individual and group WAD cyanide speciation is proposed for the first time. The speciation protocol comprises three successive measurements: (i) of non-treated, (ii) LE-exchange pre-treated; (iii) electrochemically pre-treated sample. In the presence of all WAD complexes this procedure provides complete recovery of the total bound cyanide along with its quantitative differentiation into the following groups: (1) Hg(CN)42−; (2) CN− + Cd(CN)42− + Zn(CN)42−; (3) Cu(CN)43− + Ni(CN)42− + Ag(CN)2−. The presence of a 100-fold excess in total of the following ions: CO32−, SCN−, NH4+, SO42− and Cl− does not interferes. Thus the proposed approach offers a step ahead to meeting the ever increasing demand for cyanide-species-specific methods. The equipment simplicity makes the procedure a good candidate for implementing in portable devices for in-field cyanide monitoring. 相似文献
284.
285.
Benedetto Bozzini Bertrand Busson Gian Pietro De Gaudenzi Claudio Mele Abderrahmane Tadjeddine 《Journal of Solid State Electrochemistry》2008,12(3):303-313
In this paper, the behaviour of Au(111), (100), (110) and (210) electrodes in contact with pH-neutral aqueous solutions of
KCN has been studied as a function of potential by means of in situ sum frequency generation (SFG) and difference frequency
generation (DFG) spectroscopies. The contribution of both free and bound electrons has been included. Spectroelectrochemical
results were complemented with cyclic voltammetric measurements. The main emphasis in this work has been placed on systematising
and quantifying the interaction between the vibrational and electronic structures of the electrodic interfaces studied by
the systematic comparison of SFG and DFG spectra measured under the same electrochemical conditions for different crystal
orientations. 相似文献
286.
A flow system designed with solenoid valves is proposed for determination of weak acid dissociable cyanide, based on the reaction
with o-phthalaldehyde (OPA) and glycine yielding a highly fluorescent isoindole derivative. The proposed procedure minimizes the
main drawbacks related to the reference batch procedure, based on reaction with barbituric acid and pyridine followed by spectrophotometric
detection, i.e., use of toxic reagents, high reagent consumption and waste generation, low sampling rate, and poor sensitivity.
Retention of the sample zone was exploited to increase the conversion rate of the analyte with minimized sample dispersion.
Linear response (r = 0.999) was observed for cyanide concentrations in the range 1–200 μg L−1, with a detection limit (99.7% confidence level) of 0.5 μg L−1 (19 nmol L−1). The sampling rate and coefficient of variation (n = 10) were estimated as 22 measurements per hour and 1.4%, respectively. The results of determination of weak acid dissociable
cyanide in natural water samples were in agreement with those achieved by the batch reference procedure at the 95% confidence
level. Additionally to the improvement in the analytical features in comparison with those of the flow system with continuous
reagent addition (sensitivity and sampling rate 90 and 83% higher, respectively), the consumption of OPA was 230-fold lower. 相似文献
287.
《Analytical letters》2012,45(12):2359-2379
Abstract The reactions among 4-(2-pyridylazo)resorcinol (PAR), mercury(II) and/or cyanide ion in the presence of water soluble surfactants alone or combination were systematically investigated at about pH 9. The spectrophotometric determinations of mercury(II) and cyanide ion were investigated by using the PAR-mercury(II)-HPC complex (3:2:2 molar ratio) in the presence of N-hexadecylpyridinium chloride (HPC) alone; calibration graphs were rectilinear in the ranges of 0 – 40 μg mercury(II) and 0 –10 μg cyanide ion in a final 10 ml with the apparent molar absorptivities of 5.9 × 104 for mercury(II) and 2.5 × 104 1 mol?1 cm?1 for cyanide ion at 590 nm. The proposed method had advantages—rapidity, simplicity without solvent extraction, and sensitivity in comparison with reported solvent extraction methods. The interference of foreign ions decreased 1/2–l//4-fold compared with that in the presence of non-ionic surfactant alone. 相似文献
288.
Using the strategy of template polymerization, a presynthesized specific metal‐complexing polymer (poly(methacryloylhistidine‐Ni(II)‐CN?), Ni‐CN/IP) has been specifically used to recognize cyanide ion. As described previously, nickel(II)‐methacryloylhistidine dihydrate complex monomer was synthesized and reacted with KCN to produce the monomer‐template complex. This monomer‐template complex phase was polymerized in a dispersion medium. After polymerization, the template (CN?) was removed from the Ni‐CN/IP, producing CN? ion imprinted metal‐chelate polymer. The synthesized ion imprinted polymer is examined as a novel potential cyanide selective ionophore in polymeric membrane type ion selective electrodes. Membranes formulated with Ni‐CN/IP are shown to exhibit enhanced potentiometric selectivity for cyanide over more lipophilic anions including perchlorate, iodide, and thiocyanate. Addition of lipophilic cationic sites into the organic membranes enhanced the response and selectivity towards CN? ion, while addition of lipophilic anionic sites deteriorated the response but enhanced the selectivity, indicating that the Ni‐CN/IP particles behaves via the so‐called “mixed‐mode” response mechanism. The fabricated sensors possessed good performance characteristics, in terms of life span, selectivity for CN? ion over a wide range of other interfering anions, fast response, stability and high reproducibility. Applications for direct determination of cyanide ion in hazardous wastes using the proposed sensors showed good correlation with data obtained using commercial solid state cyanide electrode, with no significant difference in the t‐test values with 95 % confidence level. An F‐test revealed that the standard deviations of the replicate sample measurements obtained by the two methods were not significantly different. 相似文献
289.
建立了离子排斥色谱-脉冲安培法测定游离CN-的检测方法。方法使用IonPac ICE-AS1离子排斥柱为分析柱,以120 mmol/L HClO4为淋洗液,安培法检测(工作电极为Pt电极)。CN-的检出限为0.42μg/L(50μL进样,三倍基线噪音);在1-1000μg/L范围内具有良好的线性(r=0.9996)。0.01 mg/L和0.1mg/LCN-分别连续进样9次,峰面积相对标准偏差(RSD)分别为4.0%和3.0%。用该方法检出了电镀液样品中大量的游离CN^-。对实际样品进行加标,其回收率在83%-117%之间。 相似文献
290.
Alexandre Labiche Augustin Malandain Maxime Molins Dr. Frédéric Taran Dr. Davide Audisio 《Angewandte Chemie (International ed. in English)》2023,62(36):e202303535
In contrast to stable and natural abundant carbon-12, the synthesis of organic molecules with carbon (radio)isotopes must be conceived and optimized in order to navigate through the hurdles of radiochemical requirements, such as high costs of the starting materials, harsh conditions and radioactive waste generation. In addition, it must initiate from the small cohort of available C-labeled building blocks. For long time, multi-step approaches have represented the sole available patterns. On the other side, the development of chemical reactions based on the reversible cleavage of C−C bonds might offer new opportunities and reshape retrosynthetic analysis in radiosynthesis. This review aims to provide a short survey on the recently emerged carbon isotope exchange technologies that provide effective opportunity for late-stage labeling. At present, such strategies have relied on the use of primary and easily accessible radiolabeled C1-building blocks, such as carbon dioxide, carbon monoxide and cyanides, while the activation principles have been based on thermal, photocatalytic, metal-catalyzed and biocatalytic processes. 相似文献