Phenylselenium Trichloride,Preparation and Use as a Vinylic Chlorination Reagent

Phenylselenium trichloride (1) is prepared from benzeneseleninic acid (2) and thionyl chloride and used to effect vinylic chlorination, viz. the conversion of 3-chloro-2-chloromethyl-1-propene (4) into 2-chloromethyl-1,3-dichloro-propene (3).     

Synthesis of unsaturated organoselenium compounds via the reaction of organic diselenides with 2,3-dichloro-1-propene in the hydrazine hydrate-KOH system

Dimethyldiselenide reacts with 2,3-dichloro-1-propene at 20–25°C in the hydrazine hydrate-KOH medium to form 2-chloro-3-methylselanyl-1-propene with 90% yield. Diphenyldiselenide in the reaction with 2,3-dichloro-1-propene, depending on the conditions, can give quite selectively four products: 2-chloro-3-phenylselanyl-1-propene, phenylselanylpropadiene, 1-phenylselanyl-1-propyne, and Z-1,2-bis(phenylselanyl)-1-propene. The effect of the selenium atom on the reaction direction and the products structure is discussed.     

Primary steps of the mechanism of gas-phase monomolecular decomposition of nitropropenes,according to results of quantum-chemical calculations (Review)

The mechanisms of gas-phase monomolecular decomposition of cis- and trans-nitropropenes, 2-nitro-1-propene, and 2-methyl-1-nitro-1-propene were examined by DFT B3LYP/6-31G(d) calculations using GAUSSIAN’98 program package. The most probable pathway of thermal decomposition of these compounds involves formation in the primary step of four-membered cyclic intermediates, substituted oxazetes. For cis-nitropropene and 2-methyl-1-nitro-1-propene, the mechanism whose primary step is 1,5-sigmatropic hydrogen shift from the CH₃ group to the NO₂ group is principally possible.     

An Atomic Absorption Analysis Method for Cyanide

Abstract

An atomic absorption analysis procedure for cyanide has been developed. The procedure is based upon the solubilization of copper(II) from a basic copper carbonate in an alkaline medium. The amount of copper complexed by the cyanide ion is determined by atomic absorption and a calibration curve is constructed concurrently. The stoichiometry of the cyanide-copper complex is 3:1, implying formation of the complex ion Cu(CN)^? ₃, with no formation of CuCN observed at the low concentration of cyanide used. The method is used primarily for analyzing low levels of cyanide; the sensitivity of the method extending down to 2.0 × 10^?5 M CN^?. The most likely interference, iron, is considered. Finally, recovery of cyanide from spiked samples is demonstrated.     

A highly selective and sensitive dual-channel chemosensor for cyanide based on sulfahydrazone derivative

A colorimetric and fluorescent cyanide probe bearing naphthol and sulfahydrazone groups has been designed and synthesized. This structurally simple probe displays a rapid response and high selectivity for cyanide in DMSO/EtOH (v/v = 2:8) solution. The addition of CN^? to the sensor p-toluenesulfonyl-2-hydroxy-1-naphthylhydrazone (L3) induced a remarkable color change from pale-yellow to yellow, and green fluorescence changed to yellow. The ¹H NMR titration and DFT calculations suggested that the selective sensing process is based on a nucleophilic addition reaction of cyanide to imine. Test strips based on sensor L3 were fabricated, which could act as a convenient and efficient test kit to detect CN^? for “in-the-field” measurements.     

Complex Formation Between Hydroxy Naphthol Blue and First Row Transition Metal Cyanide Complexes

Abstract

It has been found that cyanide complexes of first row transition metal elements exhibit enhanced binding to hydroxy naphthol blue (HNB) relative to the binding of corresponding aquo-ions. HNB forms a 2:1 complex with Fe³⁺ and Cu²⁺ cyanides, and 1:1 complexes with all other transition metal cyanide complexes studied; formation constants have been calculated from the spectrophotometric data in each case. It is possible to use HNB as a spectrophotometric reagent for transition metal cyanide complexes, lower limits of detection being determined for each complex.     

Didodecyldimethylammonium Bromide Bilayer Vesicle-Catalyzed and Uranine-Sensitized Chemiluminescence for Determination of Free Cyanide at Picogram Levels by Flow Injection Method

Abstract

A novel chemiluminescence system, didodecyldimethylammonium bromide-uranine-sodium hydroxide, is described for the determination of ultratraces of free cyanide by flow injection method. Organized surfactant assemblies(bilayer vesicles) incorporated with a sensitizer (uranine) permit the determination of free cyanide very selectively with a limit of determination of 1 pg (20-μ1 sample injection). Sulfide, the strongest CL inducer after free cyanide, provides a signal 0.1 % of that for free cyanide.     

A novel case of 1,3-asymmetric induction in rhodium-catalyzed hydroformylation of an allylic double bond using perbenzylated C-glucosides as chiral directors

1-(2′,3′,4′,6′-Tetra-O-benzyl-α-d-glucopyranosyl)-2-propene 1a and 1-(2′,3′,4′,6′-tetra-O-benzyl-β-d-glucopyranosyl)-2-propene 1b were hydroformylated at different temperatures affording linear and branched aldehydes in either a 1:1 or 2:1 regioisomeric ratio, depending on the stereochemistry of the starting substrate. The diastereoisomeric ratio of the branched isomer depended on the reaction temperature as well as the alkene structure, the highest value (85:15) being obtained in the case of hydroformylation of the α-isomer at 0 °C.     

3-Methyl-3-butenenitrile and 3-bromo-2-methyl-1-propene; normal coordinate calculations based on valence force fields

Normal coordinate calculations have been made for the actual conformers of the molecules CH₂C(CH₃)CH₂X, XCN, Br. A valence force field of 37(34) force constants reproduced the 33(30) fundamental frequencies for XCN(Br) to an average deviation of 14(11) cm⁻¹. For 3-bromo-2-methyl-1-propene the calculation suggests a reassignment. According to this, the existing experimental data may be reinterpreted as 3-bromo-2-methyl-1-propene having 2 conformers, instead of 3 as suggested earlier.     

Two new cyanide-bridged complexes, {[Cu(men)2][Ni(CN)4]}n and [Mn(bpy)2]4[Mo(CN)8]2·0.5MeOH·0.75H2O: Syntheses and crystal structures

Two novel cyano-bridged complexes, {[Cu(men)₂][Ni(CN)₄] _n (1) (men = N,N′-dimethyl-ethylenediamine) and [Mn(bpy)₂]₄[Mo(CN)₈]₂·0.5MeOH·0.75H₂O (2) (bpy = 2,2′-bipyridine) have been synthesized and structurally characterized by IR spectroscopy and X-ray crystallography. The complex 1 has onedimensional zigzag chain structure in which the Ni atom is coordinated by four cyanide groups, and the Cu atom is surrounded by four nitrogen atoms of the two men ligands in equatorial plane and two nitrogen atoms of the bridging cyanide in axial positions; the Cu centre is in a distorted octahedral environment. Owing to weak interactions, complex 1 is self-assembled into two-dimensional network via N-H...N hydrogen bonds. In 2, the basic structural unit is centrosymmetric and contains four Mn centers connected by two octacyanomolybdates via eight cyanide bridges. Each Mo atom is linked via four cyanide groups to four Mn, and the other four cyanide groups are terminal. From X-ray single crystal analysis (room temperature), 1 crystallizes in monoclinic space group P2₁/n with a = 6.7332(7) ?, b = 13.9248(15) ?, c = 9.0869(10) ?, β = 98.4030(10)°, V = 843.05(16) ?³, Z = 2; 2 crystallizes in monoclinic space group P2₁/n with a = 13.886(6) ?, b = 24.116(11) ?, c = 15.263(7) ?, β = 90.175(6)°, V = 5111(4) ?³, Z = 2. Original Russian Text Copyright ? 2009 by X. Chen, P. Yang, S.-L. Ma, S. Ren, M.-Y. Tang, Y. Yang, Z.-J. Guo, and L.-Z. Liu The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 50, No. 3, pp. 518–521, May–June, 2009.     

False Detection of Cyanide Ion in Photographic Processing Waste Solutions Using Standardized Reference Methods

Abstract

Although cyanide compounds are not incorporated in photographic processing solutions, false detection of cyanide ion is often encountered during the determination of total cyanide by various standardized methods such as ISO, ANSI and JIS. Various organic compounds and nitrogen compounds in the processing solutions were examined because of this false detection. The results suggest that hydrogen cyanide is formed by a reaction between these compounds during the distillation process for the separation of total cyanide, even though ISO, ANSI and JIS were used. The results support the following three mechanisms of cyanide formation involved in the process: (1) Hydroxylammonium salts reacts with another ingredient, formaldehyde, to form formaldoxime, which then decomposes to HCN. (2) Hydroxylammonium is oxidized by air to form nitrite ion, which subsequently reacts with organic compounds such as aminocarboxylic acids and aromatic amines (the colour-developing agent) to form HCN. (3) Potassium permanganate oxidizes aromatic amines to form HCN.     

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.     

Crystal structures of [Hg(<Emphasis Type="Italic">N</Emphasis>-ethylthiourea)<Subscript>2</Subscript>(CN)<Subscript>2</Subscript>] and [Hg(<Emphasis Type="Italic">N</Emphasis>-propylthiourea)<Subscript>2</Subscript>(CN)<Subscript>2</Subscript>]

Two mercury(II) cyanide complexes of N-ethylthiourea (Ettu) and N-propylthiourea (Prtu) ligands, [Hg(Ettu)₂(CN)₂] (1) and [Hg(Prtu)₂(CN)₂] (2), were prepared and their crystal structures were determined by X-ray crystallography. In both structures, the mercury atom is coordinated to two sulfur atoms of thioureas and two cyanide carbon atoms in a pseudo-tetrahedral mode with the bond angles in the range of 90.52(11)–162.2(3)°. The structures are stabilized by N-H—S, N-H—N, and C-H—N intramolecular and intermolecular hydrogen bonds.     

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%.     

Stereochimie de la reaction magnesienne sur deux amines bromees ethyleniques: N-benzyl N-ethyl amino-3 methyl-2 bromo-1 propene-1 et le N-benzyl N-ethyl amino-3 bromo-1 propene-1

The synthesis of vinylorganomagnesium compounds with N-benzyl-N-ethyl-3-amino-2-methyl-1-bromo-1-propene or with trans-N-benzyl-N-ethyl-1-bromol-1-propene is not stereospecific. The same reaction realised with the cis isomer gives two compounds: cis product and acetylene derivate.     

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.     

Analysis of Cyanide in Blood by Headspace-Isotope-Dilution-GC-MS

Abstract

An uncomplicated, rapid, automated procedure for the analysis of low cyanide concentrations in whole blood is reported. The analysis was performed by headspace gas chromatography and mass spectrometry in the (¹H¹²C¹⁴N) and m/z 29 (¹H¹³C¹⁵N). Carryover from cyanide adsorption onto the surface of the needle was prevented by developing a new method that enabled automated flushing of the needle in between each cyanide analysis. Results were compared of ordinary calibrations and those of isotope dilutions. The total time of analysis was 18 min for a single cyanide analysis.     

An Efficient Synthesis of the Indole Acetic Acid Metabolite of MK-0462

A palladium-catalyzed coupling of iodoaniline 2 with bis-TES propargyl alcohol 3 gives indole-3-methanol 4b in 72% yield. Displacement of the hydroxy group of 4b by sodium cyanide followed by hydrolysis of the cyano group and desilylation provides the indole acetic acid metabolite, L-749,335 (1), of the 5-HT_1D receptor agonist MK-0462.     

Elegant Synthesis of Highly Functionalized 1,2,3-Trisubstituted Cyclopentanes

The conversion of cyclic Baylis–Hillman acetates 1 into the corresponding cyano derivatives 2 was achieved using potassium cyanide in the presence of 1,4-diazabicyclo[2.2.2]octane (DABCO) in aqueous medium. The obtained Michael acceptors 2 easily add primary amines in absolute ethanol to produce a new family of 1,2,3-trisubstituted cyclpentanes 3 in good yields.     

Spectrophotometric determination of cyanide by chromogenic disulfide in water using micellar catalysis

A spectrophotometric method is developed for the determination of cyanide in aqueous solutions using chromogenic disulfide 4,4′-2bis(1-hydroxy-3,6-disulfo-8-chloro-2-naphthylazo)diphenyldisulfide (BAS-chlorine) in the presence of cetyltrimethylammonium chloride (CTMAC). The use of CTMAC allows diminishing the limit of detection for the spectrophotometric determination of cyanide to (7.2 ± 0.3) ng/mL (p = 0.95, n = 5, RSD = 29%).