Nickel dioxide

Oxidative Fluorination of Aromatic Hydrocarbons. The economically attractive oxidative fluorination of side chains in aromatic hydrocarbons with lead dioxide or nickel dioxide in Hquid HF stops at the ben2al fluoride stage (67% yield) (124). 

Dinickel trioxide Nickel dioxide Nickel monoxide Nickel subsulphide Nickel sulphide Potassium chromate Potassium dichromate... 

Figure 4. Change in interlayer distance between Ni02 sheets upon charge for an Li/LiNi02 cell. The gap (shrinkage) of ca.0.3 A in the interlayer distance is associated with the formation of nickel dioxide (kNi02) for 0.75

Nickel dioxide, 77 107 Nickel double salts, 77 113 Nickel electrodes, 3 430 72 216 Nickel electroplating solutions, 9 818t Nickel extraction, 70 791 Nickel ferrite brown spinel, formula and DCMA number, 7 348t Nickel fibers, 77 108 Nickel fluoride complexes, 77 111 Nickel fluoride tetrahydrate, 77 109-110 Nickel fluoroborate, 77 111 Nickel fluoroborate hexahydrate, 4 157t, 158, 159... 

Another example of a practical battery, but one less commonly used, is the Edison cell. The active electrode materials consist of iron and nickel dioxide in contact with an electrolyte consisting of aqueous potassium hydroxide solution. Owing to its marked instability, the Ni02 changes spontaneously to Ni203 with liberation of oxygen. The reactions responsible for the flow of current are as follows ... 

The rechargeable nickel-cadmium (Ni-Cad) batteries are used in a variety of cordless appliances such as telephones, battery operated tools, and portable computers. During discharge, cadmium metal (Cd) acts as the anode, and nickel dioxide (Ni02) as the cathode. Both metals form insoluble hydroxides due to the presence of the potassium hydroxide electrolyte. The cell reaction during discharge is... 

Nickel Dioxide, NiOa.—Presumably the substance described as nickel sesquioxide and obtained when nickel nitrate or chlorate is gently heated, or when potassium chlorate is fused with nickel chloride, really consists of the dioxide in intimate association with more or less nickel monoxide, according to circumstances (vide supra). 

The existence of nickel dioxide was first indicated by Dufau,10 who prepared barium nickelite, Ba0.2Ni02, by igniting nickel oxide and barium carbonate in an electric arc. The nickelite resulted as dark-coloured crystals of density 4-8 at 20° C. and attacked by water. 

In the hydrated form, Ni02.aH20, nickel dioxide is obtained by decomposing an aqueous solution of a nickel salt by warming with sodium or potassium hypochlorite, and by passing chlorine through a suspension of nickelous hydroxide in water.1 It also results when a neutral solution of nickel sulphate is electrolysed. In the literature it is frequently referred to and described as the hydrated sesqui-oxide. 

Numerous other substances described as oxides of nickel have been placed on record, and formulae suggested such as Ni407,5 Ni507,4 Nig05,7 NiO, and Ni302.H20.9 These are probably not separate chemical entities, but mixtures of nickel, nickelous oxide, and nickel dioxide according to circumstances. 

After reductive removal of the benzyl groups of 70, the tetrathiol 71 is obtained. 71 is cycli-sized to the tetra(thiazoline) 72 using titanium tetrachloride (45 % yield ). Final oxidation of the terminal thiazoline to the thiazole with nickel dioxide provided mirabazole C (1). 

Not only methyl groups but practically any other alkyl groups attached to aromatic rings are oxidized to carboxyls by sufficiently strong oxidants, such as nitric acid [460, 461, 462, 463, 464, 891], chromic acid and its derivatives [550, 551, 624, 633, 634, 1129, 1130], and potassium permanganate [503, 841, 880, 881, 882, 883, 1131]. Occasionally, such oxidations have been effected by other reagents, such as ozone [68], sulfomonoperacid (Oxone) [205], sodium hypochlorite [696], and nickel dioxide [933], or by electrooxidation [117] (equation 181). 

Methylquinoline-3-carboxylic acid is oxidized quantitatively by nickel dioxide in sodium hydroxide after 12 h at 25 °C to quinoline-2,3-dicarboxylic acid [933],... 

Nickel dioxide (Ni02) is a one-electron oxidant similar to Co(lll) acetate. 2,6-Di(ferf-butyl)phenol underwent Ni02-promoted oxidation in benzene (room temp., 5 h) to afford a quantitative yield of the dibenzoquinone 754 (R = f-Bu). In the case of 4-methyl-2,6-di(ferf-butyl)phenol (69), an extended diquinone 757 was produced in 31% yield (Scheme 149). 

SCHEME 149. Phenolic oxidation with cobalt(lll) acetate and nickel dioxide... 

SCHEME 150. Phenolic oxidation with nickel dioxide or catalytic rhodium complex... 

The // treatment with pyridine to 4-bromoisothiazolin-3-one 1,1-dioxide. The compounds formed by the cycloaddition reactions of 2-substituted isothiazolin-3-one 1,1-dioxides can be aromatized using ddq, manganese dioxide or nickel dioxide <89HCA1416>. 2-Acetyl-3-acetoxyl-2,3-dihydro-1,2-benzisothiazole 1,1 -dioxide (see Section 3.05.9.1.2) aromatizes with sulfuric add to 1,2-benzisothiazole 1,1-dioxide <83CC520>. 

As described above, LiNi02 is an attractive material for lithium-ion batteries. However, it is difficult to operate high-volume lithium-ion batteries consisting of LiNiOj and (natural) graphite (or other negative electrode materials) safely for thousands of cycles. The difficulty is associated with the formation of nickel dioxide, so that it is hopeless to cope with this problem in a usual manner. However, it may be possible using a characteristic feature of the solid-state redox reaction of... 

Nickel compounds in inhalable powder form (nickel monoxide, nickel dioxide, nickel sulphide, trinickel disulphide, dinickel trioxide) 1 1... 

Nickel dioxide is reduced to Ni° by HNO2, forming nitrate ... 

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