Nickel dimethylglyoxime reactions

The base was being prepared by distilling a mixture of hydroxylamine hydrochloride and sodium hydroxide in methanol under reduced pressure, and a violent explosion occurred towards the end of distillation [1], probably owing to an increase in pressure above 53 mbar. It explodes when heated under atmospheric pressure [2], Traces of hydroxylamine remaining after reaction with acetonitrile to form acetamide oxime caused an explosion during evaporation of solvent. Traces can be removed by treatment with diacetyl monoxime and ammoniacal nickel sulfate, forming nickel dimethylglyoxime [3], An account of an extremely violent explosion towards the end of vacuum distillation had been published previously [4], Anhydrous hydroxylamine is usually stored at 10°C to prevent internal oxidation-reduction reactions which occur at ambient temperature [5], See other REDOX REACTIONS... 

Dimethylglyoxime reagent soluble red iron(II) dimethylglyoxime in ammoniacal solution. Iron(III) salts give no colouration, but nickel, cobalt, and large quantities of copper salts interfere and must be absent. The test may be carried out in the presence of potassium cyanide solution in which nickel dimethylglyoxime (cf. Section III.27, reaction 8) dissolves. 

A useful spot test utilizes the fact that a suspension of red nickel dimethylglyoxime in water when treated with a neutral or acetic acid solution of a palladium salt yields the yellow palladium dimethylglyoxime, which is sparingly soluble in dilute acids. The test is best performed with dimethylglyoxime paper the latter is prepared as follows. Immerse drop-reaction paper in a 1 per cent alcoholic solution of dimethylglyoxime, dry, then immerse again in a solution of 05m nickel chloride rendered barely ammoniacal. The nickel complex precipitates wash thoroughly with water, immerse in alcohol and dry. 

Choose an appropriate precipitant and carry out the precipitation reaction. Here, an alcoholic solution of dimethylglyoxime could be used to precipitate nickel from a hot solution of aqua regia, by adding a slight excess of aqueous ammonia solution, forming a red precipitate of nickel dimethylglyoximate (Fig. 20.3). 

The concentration of nickel ions In a solution can be determined by precipitation of scarlet nickel dimethylglyoxime, Ni(DMG)2- The Ionic equation for the reaction Is as follows ... 

It is advisable to saturate the reagent (a mixture of the ketoxime and ammoniacal nickel solution) with nickel dimethylglyoxime, and to carry out the test as a spot reaction on filter paper. 

The reaction with nickel dimethylglyoxime equilibrium solution (see page 77) can be apphed with excellent results for the detection of alkaline earths and alkalis in ashes. 

A nickel content may be rapidly detected by the dimethylglyoxime reaction (see page 325). 

The anode electrode-catalyst is one of the important components of the alkaline fuel cell as it helps in the electro-oxidation of fuel. It is desirable that the anode electrode-catalyst provides faster reaction kinetics and 100% oxidation of fuels to CO2 and H2O. The most widely used catalyst, without doubt, is platinum. Platinum seems to be the best choice for acidic solutions, but other metallic alloy with platinum or other metals can match its performance in alkaline medium because of the favorable fuel oxidation in alkaline medium. Different anode materials based on Pt (Prabhuram et al. 1998, Moralldn et al. 1995, Tripkivic et al. 1996), Pt-Ru (Wang et al. 2003, Manoharan et al. 2001), Co-W alloys (Shobba et al. 2002), sintered Ag/ PdO (Koscher et al. 2003), spent carbon electrodes impregnated with Fe, Fe" or Ag (Verma 2000), nickel impregnated silicate-1 (Khalil et al. 2005) and nickel dimethylglyoxime complex (Golikand et al. 2005) are some of the catalysts studied for the electro-oxidation of methanol in alkaline medium. 

The well-known reaction of Ni(II) with dimethylglyoxime (H Dm) in alkaline medium under the influence of such oxidants as persulphate and iodine is widely used for the photometric determination of nickel. The red product (RP) of this reaction is used for this purpose. However, the nature of this red compound has not been defined yet. Using of peroxyacids makes it possible to obtain additional data concerning the conditions and mechanism of generation of RP as well as to improve the metrological pai ameters of the method. 

In another procedure [522] the sample of seawater (0.5-3 litres) is filtered through a membrane-filter (pore size 0.7 xm) which is then wet-ashed. The nickel is separated from the resulting solution by extraction as the dimethylglyoxime complex and is then determined by its catalysis of the reaction of Tiron and diphenylcarbazone with hydrogen peroxide, with spectrophotometric measurement at 413 nm. Cobalt is first separated as the 2-nitroso-1-naphthol complex, and is determined by its catalysis of the oxidation of alizarin by hydrogen peroxide at pH 12.4. Sensitivities are 0.8 xg/l (nickel) and 0.04 xg/l (cobalt). 

Nickel can be precipitated with dimethylglyoxime (DMG) according to the following reaction ... 

An additional example of a functional group undergoing reaction at the alpha atom is provided by the reactions of coordinated oximes. The earliest observation on this class of system appears to have been reported by Barker who reacted bis (dimethylglyoxime) nickel with methyl iodide and dimethyl sulfate (3). The formulations suggested for the products are archaic however, the experiments have been repeated and found to be substantially correct (31). The reactions are exemplified in Equation 47. 

Most popular schemes used to collect analytes are based on coordination reactions and electrostatic attraction. Common examples include the accumulation of nickel onto dimethylglyoxime-containing surfaces [39], the uptake and voltammetry of mercury on a diphenylcarbazide-carbon paste electrode [40], the use of surface-bound crown ethers for the collection and measurements of lead [41], or of trioctylphosphine oxide for the preconcentration of uranium [42], and the utility of polyelectrolyte-coated electrodes for the electrostatic collection of counterionic reactants [43,44], Bioaccumulation through binding to surface-bound microorganisms [45] or biocatalytic processes [46] can also offer the desired sensitivity and selectivity enhancements. 

In 1971, Otsuka etal63,64, and Klein and Nixon65 simultaneously reported the formation of nickel 7r-complexes of azobenzene. The tr-bonded structure (type IV, Fig. 3) was assigned on the basis of displacement reactions and spectroscopic evidence. Treatment of (jr-Ph—N=N-Ph)Ni (PR3)2, (R = Me, Bu, Ph), with aqueous ethanol or with dimethylglyoxime in THF resulted in the reduction of the diazeno... 

Electrography — Electrography, introduced independently by A. Glazunov and H. Fritz, is an obsolete technique for the direct electrochemical analysis of solid materials. The principle is that a solid specimen is pressed on a paper which is soaked with an electrolyte solution. By anodic oxidation of the surface of the solid specimen the reaction products (e.g., nickel(II) ions) react with a reagent in the paper (e.g., dimethylglyoxime) to give colored reaction product (red in case of nickel(II) and dimethylglyoxime). This produces a print that clearly shows the distribution of the reactive element (nickel, in our example) on the surface of the specimen. 

Dimethylglyoxime reagent yellow, crystalline precipitate of palladium dimethylglyoxime, Pd(C4H702N2)2, insoluble in m hydrochloric acid (difference from nickel and from other platinum metals) but soluble in dilute ammonia solution and in potassium cyanide solution (cf. Nickel, Section III.27, reaction 8). 

This library was exposed to a solution of Ni(II) acetate or Fe(III) chloride in order to find the most efficient ligands for these ions among the synthesized compounds. The detection of the most stable complexes could easily be accomplished using classic color reactions (dimethylglyoxime for nickel and potassium rhodanide for iron). The colored resin beads were then selected under the microscope. Actually, certain structures proved to have a very high affinity for each of these ions. In the case of sufficiently dilute Ni(II)-solutions the metal... 

Bis(dimethylglyoxime)nickel(II) reacts with both methyl iodide and methyl sulfate to give a complex in which the anionic oxygen sites are methylated 13). Similar reactions... 

The first [M Dm3(ttnFe)2](C104)2 complexes of this type were obtained [79] by the interaction of iron(II) acetate and copper, zinc, nickel, cobalt, and manganese acetates with dimethylglyoxime and 1,4,7-trimethyl-1,4,7-triazacyclononane ttn) in methanol in the presence of triethylamine (Reaction 20). In this case, a triazamacrocycle served as the protecting group in the octahedral capping nFe "03 fragment. 

The most usual method of spectrophotometric determination of nickel is using the reaction with dimethylglyoxime and an oxidizing agent (bromine, for example) in alkaline solution to form a red soluble complex (445 nm). 

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