Nickel, also

Ca.rbonylProcess. Cmde nickel also can be refined to very pure nickel by the carbonyl process. The cmde nickel and carbon monoxide (qv) react at ca 100°C to form nickel carbonyl [13463-39-3] Ni(CO)4, which upon further heating to ca 200—300°C, decomposes to nickel metal and carbon monoxide. The process is highly selective because, under the operating conditions of temperature and atmospheric pressure, carbonyls of other elements that are present, eg, iron and cobalt, are not readily formed. 

Nickel also is an important iadustrial catalyst. The most extensive use of nickel as a catalyst is ia the food iadustry ia connection with the hydrogenation or dehydrogenation of organic compounds to produce edible fats and oils (see Fats and FATTY oils). 

The reaction of a mixture of 1,5,9-cyclododecatriene (CDT), nickel acetylacetonate [3264-82-2], and diethylethoxyalurninum in ether gives red, air-sensitive, needle crystals of (CDT)Ni [12126-69-1] (66). Crystallographic studies indicate that the nickel atom is located in the center of the 12-membered ring of (CDT)Ni (104). The latter reacts readily with 1,5-cyclooctadiene (COD) to yield bis(COD) nickel [1295-35-8] which has yellow crystals and is fairly air stable, mp 142°C (dec) (20). Bis(COD)nickel also can be prepared by the reaction of 1,5-COD, triethylaluminum, and nickel acetylacetonate. 

Nitric acid can be used for the dissolution of nickel from many inorganic substances. In some cases perchloric acid is used in combination with nitric acid. Simple organic forms of nickel also can be dissolved in nitric acid. In the case of compHcated stmctural organic forms of nickel, oxidation calorimetry must be used to decompose the substances. 

Nickel also is deterrnined by a volumetric method employing ethylenediaminetetraacetic acid as a titrant. Inductively coupled plasma (ICP) is preferred to determine very low nickel values (see Trace AND RESIDUE ANALYSIS). The classical gravimetric method employing dimethylglyoxime to precipitate nickel as a red complex is used as a precise analytical technique (122). A colorimetric method employing dimethylglyoxime also is available. The classical method of electro deposition is a commonly employed technique to separate nickel in the presence of other metals, notably copper (qv). It is also used to estabhsh caUbration criteria for the spectrophotometric methods. X-ray diffraction often is used to identify nickel in crystalline form. 

Nickel also has been used as a dye site in polyolefin polymers, particularly fibers. When a nickel compound, eg, the stearate or bis(p-alkylphenol) monosulfide, is incorporated in the polyolefin melt which is subsequently extmded and processed as a fiber, it complexes with certain dyes upon solution treatment to yield bright fast-colored fibers which are useful in carpeting and other appHcations (189). Nickel stearate complexing of disperse mordant dyes has been studied (190). 

In addition to nickel alloys, nickel also forms an important alloying element in stainless steels and in cast irons, in both of which it confers additional corrosion resistance and improved mechanical and engineering properties, and in Fe-Ni alloys for obtaining controlled physical and magnetic properties (see Chapter 3). With non-ferrous metals nickel also forms important types of alloys, especially with copper, i.e. cupro-nickels and nickel silvers these are dealt with in Section 4.2. 

Termination of the plateau at a sufficiently high overpotential. The potential at which a consecutive electrode reaction sets in (e.g., hydrogen evolution in cathodic reactions) is determined by the composition of the electrolyte (specifically, the pH) and by the nature and state of the electrode surface (hydrogen overpotential). The reduction of ferricyanide in alkaline solution on nickel also provides a better-defined plateau in this respect than the deposition of copper in acid solution. 

Material Quartz and ceramic materials (Barium titanate (BaTiOQ, Lead metaniobate (PbNb2Os) and the mixed crystal Lead-zirconate titanate) Nickel or an alloy of Nickel. Also, some other high-tech alloys with ferrite materials (MFe204, M = divalent metal like Ni, Zn and Pb)... 

Nickel was first isolated in 1751, and a relatively pure metal was prepared in 1804. In nature, nickel is found primarily as oxide and sulfide ores (USPHS 1977). It has high electrical and thermal conductivities and is resistant to corrosion at environmental temperatures between -20°C and +30°C (Chau and Kulikovsky-Cordeiro 1995). Nickel, also known as carbonyl nickel powder or C.I. No. 77775, has a CAS number of 7440-02-0. Metallic nickel is a hard, lustrous, silvery white metal with a specific gravity of 8.9, a melting point of about 1455°C, and a boiling point at about 2732°C. It is insoluble in water and ammonium hydroxide, soluble in dilute nitric acid or aqua regia, and slightly soluble in hydrochloric and sulfuric acid. Nickel has an atomic weight of 58.71. Nickel is... 

Ni2 + exerts a oxytocic effect on rat uterine muscle in vitro [366]. Exposure to nickel also caused mitochondrial structural damage and accumulation of glycogen. 

Surfaces of finely divided nickel also promote the formation of aniline. A practical route to tlie preparation of electrodes coaled with a finely divided metal involves electroplating nickel onto a cathode from a solution containing a suspension of finely divided Raney nickel (Ni 50% A1 50%) or Devarda copper alloy (Cu 50% A1 45% Zn 5%), Some alloy particles stick to the cathode surface which is then activated by leaching out the aluminium using hot aqueous sodium hydroxide... 

A formal oxidation state of -1 for nickel also exists as, for example, in the nickel hydrocarbonyl, El2Ni2(CO)6. 

Elemental composition Ni 63.32%, H 2.17%, O 34.51%. The hydroxide may be digested with nitric acid, diluted appropriately, and analyzed for nickel by various instrumental methods (See Nickel). Also, water content may be measured by TGA or DTA method after decomposing the hydroxide at 230°C. The residue NiO may be characterized by x-ray and other methods (See Nickel Oxide). 

Injection studies have shown that nickel can decrease body temperature (Gordon 1989 Gordon et al. 1989 Hopfer and Sunderman 1988 Watanabe et al. 1990). Because nickel also disturbs the circadian rhythm of temperature regulation, this decrease is thought to result from an effect on the central nervous system. It has been speculated that nickel may mimic the effect of calcium on the hypothalamic thermoregulatory center resulting in hypothermia (Hopfer and Sunderman 1988). 

Humans have been exposed to nickel in nickel mines and processing plants, and numerous epidemiology studies have been performed to assess the cause of death in these workers. Accidental ingestion of nickel also has been documented in a small child and in electroplating workers. Nickel dermatitis is the most prevalent effect of nickel in humans. 

Nickel is a natural constituent of soil and is transported into streams and waterways in runoff either Ifom natural weathering or Ifom disturbed soil. Much of this nickel is associated with particulate matter. Nickel also enters bodies of water through atmospheric deposition. 

Other salts of nickel also absorb ammonia. The hexammine of nickel perchlorate, [Ni(NH3)6](C104)2, may be mentioned, as this substance has been suggested as a delicate test for nickel.3... 

Palladium on charcoal (Pd/C) is commonly used in the catalytic hydrogenation of pyrimidines in acidic media to form 1,2,4,5-tetrahydro derivatives which are stabilized as amidinium salts (62JOC2170, 65JCS1406). Platinum effects hydrogenation of the 5,6-double bond of uracils, for example, in the addition of deuterium to produce [5,6-2H2]5,6-dihydrouracil. The use of rhodium-on-charcoal and Raney nickel also gives good results. The addition of hydrogen to the 5,6-bond of thymidine and other 5-substituted uridines is stereospecific with rhodium-on-alumina as catalyst. 

Nickel also may act to stimulate or inhibit the release of various hormones (Nielsen, 1971. 1972 Dormer et al., 1973 Clay, 1975 Harak-Sunderman, 1975). Nickel has been found to inhibit insulin release from the pancreas (Dormer et al.. 1973 Clay, 1975). and stimulates glucagon secretion (Horak-S underman, 1975). 

For handling hot sea water, Carpenter 20 impeller and casings have been used with success. Cupro-nickel also has been used for pumps handling hot sea water. 

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