Preparation and Spectral Investigation of Bis[N(2-methyl-phenyl) 4-Nitro-thiobenzamidato] mercury(II), Bis[N(2-methoxy-phenyl) 4-Nitro-thiobenzamidato]mercury(II), and Bis[N(2-chloro-phenyl) 4-Nitro-thiobenzamidato]mercury(II) Complexes

Several preparative routes to bis[N(substituted-phenyl) 4-nitro-thiobenzamidato] mercury(II) complexes are presented, including the reaction of mercury(II) oxide, fluoride, chloride, bromide, cyanide, acetate, and nitrate with N(substituted-phenyl) 4-nitro-thiobenzamide derivatives. ¹ H-NMR, Raman, and IR measurements confirmed the complexation of mercury to sulphur.     

Indirect Atomic Absorption Spectrometric Determination of Ammonia,Thiosulfate and Cyanide in an Unsegmented Flow System

Abstract

A flow injection analysis method (FIA), has been developed for the determination of cyanide, thiosulfate and ammonia by atomic absorption spectrometry (AAS). Aqueous solution of the analyte was injected into an on-line column containing glass beads and packed with silver chloride and deionized water was used as the carrier. The analyte dissolves the silver chloride and the dissolved silver complex is introduced to the nebulizer of the AAS. This method has proved to be sensitive, simple and precise. Detection limits of 1.0 × 10^?7 M, 5.0×10^?7 M and 5.0x10^?6M were obtained for thiosulfate, cyanide and ammonia, respectively. The precision of the technique was 2.0%, 2.4% and 1.4% in case of thiosulfate, cyanide and ammonia, respectively. The effects of flow rate and sample volume on the FIA/AAS signals are presented.     

A Convenient Synthesis of 2,3-Diphenyl-2-cyanooxiranes

Several studies¹ have been reported on the synthesis of 2,3-diphenyl-2-cyanooxiranes. Kohler and Brown^la synthesized the oxirane in ca. 30% yield by reaction of desyl chloride with potassium cyanide in aqueous alcohol. However, the method which they employed seems to be rather complicated. Such reaction of desyl bromide with cyanide ion has not been studied in detail. We now report that cis- and trans-2,3-diphenyl-2-cyanooxiranes (2a-d and 3a-d) are conveniently obtained in good yields by reaction of 4′-substituted desyl bromide (1a-d) with 40% aqueous potassium cyanide in a mixture of dichloromethane and triethylbenzylammonium chloride (TEBAC); the total yield of 2c and 3c, for example, was as high as 86%. When cethyltriethylammonium bromide was used as a     

Vinyl Chloride-Vinyl Bromide Copolymers

Abstract

Radical copolymerization kinetics of vinyl chloride (VC) and vinyl bromide (VB) lead to the following reactivity ratios r_VC=0.825 r_VB=1.05 Vinyl bromide acts as a chain transfer agent, more powerful than vinyl chloride, the transfer constant for VC radicals being 8.5 × 10^?3 at 40° C. Neither thermal nor ionic degrad-ation produce controlled distribution of short diene sequences in the copolymer. In the ionic process initiated with LiCl or LiBr in dimethylformamide solution, substitution of halogen atoms as well as acid elimination takes place.     

Some Tetrahedral Coordination Polymers of Zinc(II), Cadmium(II), and Mercury(II) Involving 4-Aminomethylpyridine

Abstract

Analytical data and infrared spectral measurements down to 200 cm^?1 on the 1:1 compounds formed by the interaction of zinc(II) and cadmium(II) thiocyanates and mercury(II) chloride and bromide with 4-aminomethylpyridine indicate that the compounds are coordination polymers having tetrahedral stereochemistry with bidentate bridging 4-aminomethylpyridine molecules and terminally bonded halogen/pseudohalogen groups in the solid state.     

An iodide/anion exchange route to benzimidazolylidene silver complexes from benzimidazolium iodide: Crystal structures of N,N′-dibutylbenzimidazolylidene silver chloride, bromide, cyanide and nitrate

Syntheses of N,N′-dibutylbenzimidazolylidene silver complexes having chloride, nitrate or cyanide as an anion part through an iodide/anion exchange from N,N′-dibutylbenzimidazolium iodide are described, representing a practical route to benzimidazolylidene silver complexes from readily accessible benzimidazolium iodide. The crystal structures of N,N′-dibutylbenzimidazolylidene silver chloride, bromide, cyanide and nitrate have been determined, showing a close ligand-unsupported Ag-Ag interaction in [(NHC)₂]Ag⁺[AgX₂]⁻ and a “T” shape geometry about the silver(I) cation in complexes of chloride, bromide and cyanide, but a nearly linear shape in the bis(N,N′-dibutylbenzimidazolylidene) silver complex [ with non-coordinating nitrate anion.     

FORMATION OF 2-PYRIDINYL-2-OXAZOLINES AND PYRIDINE-2-CARBOXAMIDINE IN THE COORDINATION SPHERE OF COPPER(II)

Abstract

The reaction of pyridine-2-carbonitrile (2-CNpy) with 2-amino-2-hydroxymethyl-1,3-propanediol (L¹) and 2-amino-2-methyl-1-propanol (L²) in methanolic solutions of anhydrous copper(II) chloride at room temperature led to the formation of solid complexes containing 2-(2-pyridinyl)-4,4-bis(hydroxynmethyl)-2-oxazoline (pyoxaL¹) and 2-(2-pyridinyl)-4,4-dimethyl-2-oxazoline (pyoxaL²), respectively. With copper(II) bromide instead of copper(II) chloride, along with the oxazoline complexes, the complex dibromo-bis(pyridine-2-carbox-amidine)copper(II) was isolated. Under several hour reflux, the complexes dihalogenobis(pyridine-2-carboxamidine)copper(II) are the only isolable products both for chloride and bromide starting salts. The stereochemistry of the complexes and the mode of ligand coordination have been determined by spectroscopic and conductometric measurements. The crystal structure of bromobis[(2-(2-pyridinyl)-4,4-dimethyl)-2-oxazoline]copper(II) bromide hydrate was solved by X-ray diffraction techniques. The mechanism of 2-CNpy transformation to the final products is proposed.     

Potentiometric titration and differentiation of cyano and nitrito complexes of Ir(III), Pt(II), and Pd(II)

Summary The precipitation titration of the nitrito complexes of Ir(III), Pt(II), and Pd(II) vs. cetylpyridinium chloride is reported. The corresponding cyanide complexes of these precious metals are also precipitated by silver nitrate, which does not react with the nitrito complexes. Differentiation of the 2 types of complexes is, therefore, possible. Sequential estimation of the cyanide complexes and some anions such as bromide, cyanide, and aurocyanide is feasible with silver nitrate.

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Potentiometrische Titration und Differenzierung von Cyano- und Nitrito-Komplexen von Ir(III), Pt(II) und Pd(II)

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Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract number W-7405-ENG-48     

Microdetermination of Cyanide

Abstract

A volumetric procedure is described for the micro-determination of cyanide. Small amounts of cyanide can be estimated even in presence of chloride if it is present in the electrolytic bath. N-Bromosuccinimide (NBS) is used to quantitatively oxidized cyanide to cyanate. The end point is reached when the rose red color of the bordeaux red is changed to distinct yellow. From 1–6 mg. of cyanide were analyzed with an average relative standard deviation of about 0.66%.     

Color Reaction Between 4-(2-Pyridylazo)Resorcinol and Mercury (II) in the Presence of Surfactant,and Improved Spectrophotometric Determinations of Mercury(II) and Cyanide Ion with its Coloring

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.     

Turn‐On Fluorogenic Probes for the Selective and Quantitative Detection of the Cyanide Anion from Natural Sources

We report new indene derivatives that are good fluorogenic probes for the cyanide anion, one of which is a highly selective and sensitive fluorogenic probe for the fluorescent detection—as well as reliable quantification—of the cyanide anion in water or buffer, with a 10³‐fold increase of fluorescence and low detection limit. It is therefore useful for the quantification of natural cyanide from aqueous extracts of green almond seeds, thus proving that the system is suitable for fast detection and quantification of cyanide from natural sources.     

Reaction‐Based Colorimetric and Ratiometric Fluorescence Sensor for Detection of Cyanide in Aqueous Media

A stilbene‐based compound ( 1 ) has been prepared and was highly selective for the detection of cyanide anion in aqueous media even in the presence of other anions, such as F^?, Cl^?, Br^?, I^?, ClO₄^?, H₂PO₄^?, HSO₄^?, NO₃^?, and CH₃CO₂^?. A noticeable change in the color of the solution, along with a prominent fluorescence enhancement, was observed upon the addition of cyanide. The color change was observed upon the nucleophilic addition of the cyanide anion to the electron‐deficient cyanoacrylate group of 1 . The spectral changes induced by the reaction were analyzed by comparison with two model compounds, such as compound 2 with dimethyl substituents and compound 3 without a cyanoacrylate group. An intramolecular charge‐transfer (ICT) mechanism played a key role in the sensing properties, and the mechanism was supported by DFT/TDDFT calculations.     

Use of an Aqueous Micellar Medium to Improve the Spectrophotometry Determination of Cyanide Ion with 5,5′-Dithiobis(2-Nitrobenzoic Acid)

Abstract

The spectrophotometric method for the determination of cyanide, which is based on the reaction of cyanide ion with 5,5′-dithiobis(2-nitrobenzoic acid) to displace the corresponding absorbing thiol anion, has been reinvestigated using an aqueous cetyltrimethylammonium bromide micellar reaction medium. The rate of the analytical reaction is increased considerably in the presence of the cationic surfactant. Thus, the time required for the spectrophotometric determination of cyanide ion in the 0.18 – 2.80 μg/ml range using this procedure is decreased from 25 minutes to 1 – 3 minutes.     

A Chemodosimetric Probe Based on a Conjugated Oxidized Bis‐Indolyl System for Selective Naked‐Eye Sensing of Cyanide Ions in Water

A new bis‐indolyl‐based colorimetric probe has been synthesized. This allows a Michael‐type adduct formation for the detection of cyanide ions. The probe shows a remarkable color change from red to colorless upon addition of the cyanide ions in pure water. The cyanide ion reacts with the probe and removes the conjugation of the bis‐indolyl moiety of the probe with that of the 4‐substituted aromatic ring. This renders the probe colorless. The mechanism of the reaction of the probe with the cyanide ion was established by using ¹H and ¹³C NMR spectroscopy, mass spectrometry, and kinetic studies.     

Synthesis and Structural Assignment of 1-O-Acetyl-2,3,5-tri-O-benzoyl-4-(thymin-1-yl)-α-l-lyxofuranose

Abstract

Analogues of nucleosides in which the nucleobase is fixed onto the C-4 of the sugar moiety are generally prepared either from 4,5-unsaturated sugar derivatives or via a formaldehyde condensation.¹ We tested the furanosyl bromide reactivity of 1 ² towards a series of nucleophiles, mostly azides or cyanides, without success. Conversely, the nucleosidation of 1 using 5-methyl-2,4-bis(trimethyl-silyloxy)pyrimidine in the presence of stannic chloride took place at the second anomeric position (C-4) and led to the isolation in acceptable yield (47%) of a unique anomer 2 (Scheme 1).     

Highly Selective and Sensitive Triiodide PVC‐Based Membrane Electrode Based on a New Charge Transfer Complex of 2‐(((2‐(((E)‐1‐(2‐Hydroxyphenyl) Methylidine) Amino) Phenyl) Imino) Methyl) Phenol for Nano‐Level Monitoring of Triiodide

Abstract

A highly selective and sensitive triiodide sensor based on a 2‐(((2‐(((E)‐1‐(2‐hydroxy phenyl) methylidine) amino) phenyl) imino) methyl) phenol with iodine (CTC) as membrane carrier was developed. The electrode revealed a Nernstian behavior over a very wide triiodide‐ion concentration range (5.0×10^?8–1.0×10^?2 M), and relatively low detection limit (3.0×10^?8 M). The potentiometric response is independent of the pH of solution in the pH range of 3.0–10.0. The electrodes manifest advantages of low resistance, very fast response (<12 s), and most importantly, good selectivities relative to a wide variety of inorganic and organic anions, including iodide, bromide, chloride, fluoride, sulfite, sulfate, cyanide, thiocyanate, and acetate. In fact, the selectivity behavior of the proposed triiodide ion‐selective electrode shows great improvements compared to the previously reported electrodes for the triiodide ion. The proposed membrane sensor can be used for at least 6 months without any significant divergences in the potential. The electrode was successfully applied as an indicator electrode in the titration of triiodide with thiosulfate ion.     

The Rapid Determination of Orthophosphate,Sulfate, and Chloride in Natural Water Samples With High Iron Concentrations Using Ion Chromatography

Abstract

A rapid procedure has been developed for the analysis of orthophosphate, sulfate and chloride in riverine sediment interstitial water samples which have dissolved iron concentrations ranging from 0.5–2 mmol L^?1. Interferences caused by the precipitation of iron hydroxides resulting from air oxidation of ferrous iron in the anoxic samples and from the alkaline working pH range (9.0 – 10.5) of the Dionex¹ ion chromatographic system were eliminated by complexing the iron with cyanide. Orthophosphate concentration values are compared with dissolved reactive phosphate concentration data for the same samples. Orthophosphate concentrations rather than dissolved reactive phosphate concentrations are preferred for phosphate mineral solubility calculations and for phosphorus nutrient measurements.     

A Multifunctional Bimetallic Molecular Device for Ultrasensitive Detection,Naked‐Eye Recognition,and Elimination of Cyanide Ions

A new bimetallic Fe^II–Cu^II complex was synthesized, characterized, and applied as a selective and sensitive sensor for cyanide detection in water. This complex is the first multifunctional device that can simultaneously detect cyanide ions in real water samples, amplify the colorimetric signal upon detection for naked‐eye recognition at the parts‐per‐million (ppb) level, and convert the toxic cyanide ion into the much safer cyanate ion in situ. The mechanism of the bimetallic complex for high‐selectivity recognition and signaling toward cyanide ions was investigated through a series of binding kinetics of the complex with different analytes, including CN^?, SO₄^2?, HCO₃^?, HPO₄^2?, N₃^?, CH₃COO^?, NCS^?, NO₃^?, and Cl^? ions. In addition, the use of the indicator/catalyst displacement assay (ICDA) is demonstrated in the present system in which one metal center acts as a receptor and inhibitor and is bridged to another metal center that is responsible for signal transduction and catalysis, thus showing a versatile approach to the design of new multifunctional devices.     

Cyanation of Aryl Bromides with K4[Fe(CN)6] Catalyzed by Dichloro[bis{1‐(dicyclohexylphosphanyl)piperidine}]palladium,a Molecular Source of Nanoparticles,and the Reactions Involved in the Catalyst‐Deactivation Processes

Dichloro[bis{1‐(dicyclohexylphosphanyl)piperidine}]palladium [(P{(NC₅H₁₀)(C₆H₁₁)₂})₂PdCl₂] ( 1 ) is a highly active and generally applicable C? C cross‐coupling catalyst. Apart from its high catalytic activity in Suzuki, Heck, and Negishi reactions, compound 1 also efficiently converted various electronically activated, nonactivated, and deactivated aryl bromides, which may contain fluoride atoms, trifluoromethane groups, nitriles, acetals, ketones, aldehydes, ethers, esters, amides, as well as heterocyclic aryl bromides, such as pyridines and their derivatives, or thiophenes into their respective aromatic nitriles with K₄[Fe(CN)₆] as a cyanating agent within 24 h in NMP at 140 °C in the presence of only 0.05 mol % catalyst. Catalyst‐deactivation processes showed that excess cyanide efficiently affected the molecular mechanisms as well as inhibited the catalysis when nanoparticles were involved, owing to the formation of inactive cyanide complexes, such as [Pd(CN)₄]^2?, [(CN)₃Pd(H)]^2?, and [(CN)₃Pd(Ar)]^2?. Thus, the choice of cyanating agent is crucial for the success of the reaction because there is a sharp balance between the rate of cyanide production, efficient product formation, and catalyst poisoning. For example, whereas no product formation was obtained when cyanation reactions were examined with Zn(CN)₂ as the cyanating agent, aromatic nitriles were smoothly formed when hexacyanoferrate(II) was used instead. The reason for this striking difference in reactivity was due to the higher stability of hexacyanoferrate(II), which led to a lower rate of cyanide production, and hence, prevented catalyst‐deactivation processes. This pathway was confirmed by the colorimetric detection of cyanides: whereas the conversion of β‐solvato‐α‐cyanocobyrinic acid heptamethyl ester into dicyanocobyrinic acid heptamethyl ester indicated that the cyanide production of Zn(CN)₂ proceeded at 25 °C in NMP, reaction temperatures of >100 °C were required for cyanide production with K₄[Fe(CN)₆]. Mechanistic investigations demonstrate that palladium nanoparticles were the catalytically active form of compound 1 .     

Coated-Wire Ion-Selective Electrodes Based on Chlorideand Cyanide Complexes of Zinc and their Application to Zinc Monitoring in the Electrogalvanizing Process

Abstract

An indirect potentiometric method based on the selective monitoring of chlorozincate (II) or cyanozincate (II) anions with a coated-wire electrode was studied. The electroactive membrane contains either the chlorozincate or the cyanozincate salt of the tricaprylylmethylammonium cation (Aliquat 336S). Both electrodes show a useful response over the concentration range from 10^?5 to 10^?1M Zn (II) in chloride or cyanide containing solutions. Interferences arise only from a few transition metals such as Cu (II), Cd (II) and Hg (II). This method can be applied to the conditions used in the electrogalvanizing process and to industrial waste management from electroplating plants.