Catalysts dimethylglyoxime

Sponge Nickel Catalyst Dissolve approximately 100 mg of sample in about 2 mL of hydrochloric acid, and dilute to about 20 mL with water. Place 5 mL of this solution into a test tube, add a few drops of bromine water, and make it slightly alkaline with ammonium hydroxide. Add 2 to 3 mL of a 1% solution of dimethylglyoxime in alcohol. An intense red color or precipitate forms. 

There is an extensive chemistry of frans-bisdioximes such as dimethylglyoxime. They provide model systems for vitamin BJ2 and can be oxygen carriers and catalysts.199... 

A simple procedure for the preparation of Ni/Si02 catalysts involves the precipitation of nickel dimethylglyoxime from a suspension of silica in an aqueous solution of a nickel salt.38,39 Calcination is not required since the resulting supported precipitate is easily reduced in a stream of hydrogen at 200°-250°C, giving very highly dispersed supported nickel catalysts. 

The content of nickel in catalyst samples was determined by a standard chemical analysis, using dimethylglyoxime. 

An early example for cobalt-catalysed Mizoroki-Heck-type reactions with aliphatic halides by Branchaud and Detlefsen showed that an intermolecular substitution of styrene (2) could be achieved with [Co(dmgH)2py] (70) (dmgH = dimethylglyoxime monoanion) as catalyst in the presence of visible light. This radical reaction led selechvely to the substitution products when using stoichiometric amounts of Zn (27) and pyridine (31) as additives (Scheme 10.24) [52]. 

The cobaloxime(II) derivatives [Co(Hdmg)2(Ph3P)d and [CoCHdmgV pyal, where Htdmg is dimethylglyoxime, are catalysts for the oxidation of o-phenylenediamine (OPD) by atmospheric O2 at ambient temperature. In acetone, methyl ethyl ketone or cyclohexanone as solvents, cyclization to 2,2-disubstituted dihydrobenzimidazoles (DHB) is followed by... 

That two independent catalyst sites are involved in these processes is indicated by the fact that the AIEtg/VCla system, a stem which polymerizes butene-1 but is unable to isomerize butene-2, can be used as isomerization-polymerization catalyst in the presence of a third cmnponent (e.g.. Ni-dimetlqrlglyoxime) the sole function of which is the positional isomerization of butene-2 to butene-1 (the Ni-dimethylglyoxime is not a polymerization catal3 ). A very similar observation was made with pen-tene-2 which gave polypentene-1 in the presence of the AnSt QJ Fe(acac)2 system. 

The use of cobalt and manganese cocatalysts with TEMPO and its derivatives has been known for some time. The utilization of nitrate salts suggests that the oxoammonium salt oxidizes the substrates. There are also reports with heterogeneous Cu/Mn oxide cocatalysts in these cases low loadings of TEMPO were used while the heterogeneous catalyst can be recycled. Cobalt can be used as a sole effective metallic component within a Co(N03)2/dimethylglyoxime/TEMPO system, with only 1 mol% catalyst loadings. 

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. 

Catalyst synthesis for methanol oxidation/cyclic voltammetry Nickel electrode modified by nickel dimethylgly-oxime complex NaOH solution Dimethylglyoxime ligand deposition on the mechanically pretreated nickel disc... 

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