Dimethylglyoxime is a chemical compound described by the formula CH3C(NOH)C(NOH)CH3. Its abbreviation is dmgH2 for neutral form, and dmgH for anionic form, where H stands for hydrogen. This colourless solid is the dioxime derivative of the diketone butane-2,3-dione (also known as diacetyl). DmgH2 is used in the analysis of palladium or nickel. Its coordination complexes are of theoretical interest as models for enzymes and as catalysts. Many related ligands can be prepared from other diketones, e.g. benzil.
Preparation[edit]
Synthesis of a Nickel complex was determined by adding ethylenediamine and ethanol. After obtaining close to 1.000g of nickel(II) sulfate hexahydrate, with your partner as instructed in step one, we quantitatively transferred it to a 250mL beaker with no more than 3mL of water.
Dimethylglyoxime can be prepared from butanone first by reaction with ethyl nitrite to give biacetyl monoxime. The second oxime is installed using sodium hydroxylamine monosulfonate:[1]
Complexes[edit]
Dimethylglyoxime is used to detect and quantify nickel, which forms the bright red complex nickel bis(dimethylglyoximate) (Ni(dmgH)2). The reaction was discovered by L. A. Chugaev in 1905.[2]
Cobalt complexes have also received much attention. In chloro(pyridine)cobaloxime[3] the macrocycle [dmgH]22â mimics the macrocyclic ligand found in vitamin B12.
Structure of chloro(pyridine)cobaloxime.
References[edit]
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Dimethylglyoxime&oldid=931825982'
The test tube in the middle contains a precipitate of nickel(II) hydroxide
Nickel(II) hydroxide is the inorganic compound with the formula Ni(OH)2. It is an apple-green solid that dissolves with decomposition in ammonia and amines and is attacked by acids. It is electroactive, being converted to the Ni(III) oxy-hydroxide, leading to widespread applications in rechargeable batteries.[4]
Properties[edit]
Nickel(II) hydroxide has two well-characterized polymorphs, α and β. The α structure consists of Ni(OH)2 layers with intercalated anions or water.[5][6] The β form adopts a hexagonal close-packed structure of Ni2+ and OHâ ions.[5][6] In the presence of water, the α polymorph typically recrystallizes to the β form.[5][7] In addition to the α and β polymorphs, several γ nickel hydroxides have been described, distinguished by crystal structures with much larger inter-sheet distances.[5]
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The mineral form of Ni(OH)2, theophrastite, was first identified in the Vermion region of northern Greece, in 1980. It is found naturally as a translucent emerald-green crystal formed in thin sheets near the boundaries of idocrase or chlorite crystals.[8] A nickel-magnesium variant of the mineral, (Ni,Mg)(OH)2 had been previously discovered at Hagdale on the island of Unst in Scotland.[9]
Reactions[edit]
Nickel(II) hydroxide is frequently used in electrical car batteries.[6] Specifically, Ni(OH)2 readily oxidizes to nickel oxyhydroxide, NiOOH, in combination with a reduction reaction, often of a metal hydride (reaction 1 and 2).[10]
Reaction 1 Ni(OH)2 + OHâ â NiO(OH) + H2O + eâ
Windows 10 burn dmg to usb converter. Reaction 2 M + H2O + eâ â MH + OHâ
Net Reaction (in H2O)Ni(OH)2 + M â NiOOH + MH
Synthesis Of Ni Dmg 2016
Of the two polymorphs, α-Ni(OH)2 has a higher theoretical capacity and thus is generally considered to be preferable in electrochemical applications. However, it transforms to β-Ni(OH)2 in alkaline solutions, leading to many investigations into the possibility of stabilized α-Ni(OH)2 electrodes for industrial applications.[7]
Synthesis[edit]
The synthesis entails treating aqueous solutions of nickel(II) salts with potassium hydroxide.[11]
Toxicity[edit]
The Ni2+ ion is a known carcinogen. Toxicity and related safety concerns have driven research into increasing the energy density of Ni(OH)2 electrodes, such as the addition of calcium or cobalt hydroxides.[4]
See also[edit]References[edit]
External links[edit]Synthesis Of Ni Dmg 2017
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