Nickel hydrolysis reactions

The review of Martynova (18) covers solubilities of a variety of salts and oxides up to 10 kbar and 700 C and also available steam-water distribution coefficients. That of Lietzke (19) reviews measurements of standard electrode potentials and ionic activity coefficients using Harned cells up to 175-200 C. The review of Mesmer, Sweeton, Hitch and Baes (20) covers a range of protolytic dissociation reactions up to 300°C at SVP. Apart from the work on Fe304 solubility by Sweeton and Baes (23), the only references to hydrolysis and complexing reactions by transition metals above 100 C were to aluminium hydrolysis (20) and nickel hydrolysis (24) both to 150 C. Nikolaeva (24) was one of several at the conference who discussed the problems arising when hydrolysis and complexing occur simultaneously. There appear to be no experimental studies of solution phase redox equilibria above 100°C. 

Gel Preparation NiO/A C gels are prepared using the method suggested by Teichner and co-workers (4). Aluminum sec-Butylate is dissolved in sec-Butanol while Nickel Acetate is dissolved in Methanol separately. Water is added to the second mixture in near stoichiometric amounts necessary for the hydrolysis reactions. The two solutions are mixed and a precipitate of alumina is immediately formed. Gels are dried immediately after preparation, in order to eliminate the effect of aging (2). 

The xenon hexafluoride for this synthesis is best prepared by reaction of xenon with an excess of fluorine at 300° in a nickel or Monel apparatus. Extremely pure XeFs is not required. Xenon hexafluoride attacks glass, and should be stored in a nickel or Monel container until ready for use. The hydrolysis reaction is violent, and if more than a hundred milligrams of XeFe is to be hydrolyzed, special safety precautions must be taken. Face shields, heavy gloves, and a sturdy plastic explosion barrier between the hydrolysis apparatus and the experimenter are strongly recommended. No more than about 3 g. of XeFg should be hydrolyzed in one batch. 

Binding of the substrate urea to a nickel ion in urease is an integral part of the mechanism in the hydrolysis reaction (Nielsen 1984). Both ruminants and monogastric animals require urease for the decomposition of urea into ammonia, which is needed for the microbial synthesis of ammonia that, in turn, is necessary for amino acid and protein synthesis. This process also takes place in the appendix of monogastric animals and some species of ruminants (roe deer). 

Calorimetric studies by acid titration of hydrolysed nickel(II) solutions have been performed at 25°C in 3 M (Na)Cl ionic medium in order to obtain the enthalpy of the hydrolysis reactions. The experimental data have been interpreted using the hydrolysis mechanisms proposed by Burkov and Lilich [65BUR/LIL2] and Biederman and Ohtaki (cited as a personal communication to the author [68ARN]). The latter values... 

Among the mononuclear hydrolytic species of nickel, only the stability of NiOH is well documented. Baes and Mesmer (14) have compiled the following values for the hydrolysis reactions ... 

The hydrolysis reaction is preferably carried out under alkaline conditions. Acid hydrolysis can lead to undesired side reactions and also incomplete reaction. Hydrolysis by water under pressure is also incomplete, especially in the case of aromatic polyurethanes. Alkaline hydrolysis in glass containers can give large amounts of silicate which interfere with subsequent analysis, and for this reason the use of steel or even nickel-coated steel containers is recommended. The hydrolysis of polyester urethanes yields the diamine from the diisocyanate, and the acid salt and glycols from the polyester. Hydrolysis of polyether urethanes yields the diamine and the polyether. If diamines are used as curatives then two diamines will be present in the hydrolysis products. 

Indeed, numerous experimental studies have been performed to study the evolution of the enviromnent in a crevice. Most data were obtained in actively corroding artificial crevices or pits, either by sampling the solution or by direct pH and Cr concentration measurements. Table 1 summarizes significant results that confirm the foregoing trends. In crevice solutions, the drop of pH depends on the hydrolysis constants of the metal cations. On stainless alloys, chromium and molybdenum are considered to be the cause of the very low, sometimes negative, pH observed. Iron, nickel, and aluminiun exhibit much less acidic hydrolysis reactions and the pH values in the crevices are higher values of 3 to 5 are reported for iron, values of 3 to 4 for the aluminum alloys. 

The nitroso-phenol reaction, when applied to extractives of chlorodyne, is subject to interference from substances other than morphine present in the residue. Garratt- drew attention to apparent morphine contents of treacle. McLachlan " reported the interference from liquorice as being due to the colour which develops with ammonia and glycyrrhizin and some of its hydrolysis products. The apparent morphine contents of both treacle and liquid extract of liquorice were also reported on in 1956. By the extraction procedure detailed below morphine can be separated from the substances present in liquorice which give a yellow colour with ammonia and the iodic acid-nickel chloride reaction may then be applied. 

Actually, the drop of pH is related to more complex reactions and species. Thus, in more sophisticated models, several hydrolysis reactions and metal chloride formation are taken into account but the selection of species and reactions is somewhat different from model to model. Oldfield and Sutton [94] and Watson and Postlethwaite [2] considered only hydroxides as the product of cation hydrolysis. Sharland [96] introduced simple metallic chlorides. The most complete set of species and reactions has been used by Bernhardsson et al. [4], which made available the thermodynamic data of a large number of species, including several iron, nickel, chromium, and molybdenum polycations as well as metal chlorides and hydroxychlorides. Gartland [19] used a more limited set of species (Table 10.3) selected among the Bernhardsson data. According to their experimental results, Hebert and Alkire [95] included Al(OH) " as the hydrolysis product in their model of the crevice corrosion of aluminum alloys. 

Liu et al. (2003) studied the oxidation of BH2 on nickel electrocatalyst and reported that the reaction proceeds by the four-electron rather than eight-electron pathways. Normally, Na" " or K" cations in the solution do not influence the four-electron reaction pathways. The four-electron reaction pathways and hydrolysis reaction leads to a decrease in efficiency of oxidation. A suitable catalyst should be identified such that the eight electron mechanism of electro-oxidation of NaBH4 is followed. Otherwise, hydrogen gas generated from four-electron mechanism of electro-oxidation should be utilized to maintain higher efficiency. 

Active Raney nickel induces desulfurization of many sulfur-containing heterocycles thiazoles are fairly labile toward this ring cleavage agent. The reaction occurs apparently by two competing mechanisms (481) in the first, favored by alkaline conditions, ring fission occurs before desul-, furization, whereas in the second, favored by the use of neutral catalyst, the initial desulfurization is followed by fission of a C-N bond and formation of carbonyl derivatives by hydrolysis (Scheme 95). 

Adiponitrile undergoes the typical nitrile reactions, eg, hydrolysis to adipamide and adipic acid and alcoholysis to substituted amides and esters. The most important industrial reaction is the catalytic hydrogenation to hexamethylenediarnine. A variety of catalysts are used for this reduction including cobalt—nickel (46), cobalt manganese (47), cobalt boride (48), copper cobalt (49), and iron oxide (50), and Raney nickel (51). An extensive review on the hydrogenation of nitriles has been recendy pubUshed (10). 

Another synthesis of pyrogaHol is hydrolysis of cyclohexane-l,2,3-trione-l,3-dioxime derived from cyclohexanone and sodium nitrite (16). The dehydrogenation of cyclohexane-1,2,3-triol over platinum-group metal catalysts has been reported (17) (see Platinum-GROUP metals). Other catalysts, such as nickel, rhenium, and silver, have also been claimed for this reaction (18). 

Replacement of halides with deuterium gas in the presence of a surface catalyst is a less useful reaction, due mainly to the poor isotopic purity of the products. This reaction has been used, however, for the insertion of a deuterium atom at C-7 in various esters of 3j -hydroxy-A -steroids, since it gives less side products resulting from double bond migration. Thus, treatment of the 7a- or 7j5-bromo derivatives (206) with deuterium gas in the presence of 5% palladium-on-calcium carbonate, or Raney nickel catalyst, followed by alkaline hydrolysis, gives the corresponding 3j3-hydroxy-7( -di derivatives (207), the isotope content of which varies from 0.64 to 1.18 atoms of deuterium per mole. The isotope composition and the stereochemistry of the deuterium have not been rigorously established. 

In 1965, Breslow and Chipman discovered that zinc or nickel ion complexes of (E)-2-pyridinecarbaldehyde oxime (5) are remarkably active catalyst for the hydrolysis of 8-acetoxyquinoline 5-sulfonate l2). Some years later, Sigman and Jorgensen showed that the zinc ion complex of N-(2-hydroxyethyl)ethylenediamine (3) is very active in the transesterification from p-nitrophenyl picolinate (7)13). In the latter case, noteworthy is a change of the reaction mode at the aminolysis in the absence of zinc ion to the alcoholysis in the presence of zinc ion. Thus, the zinc ion in the complex greatly enhances the nucleophilic activity of the hydroxy group of 3. In search for more powerful complexes for the release of p-nitrophenol from 7, we examined the activities of the metal ion complexes of ligand 2-72 14,15). 

Delmas and his co-workers have done extensive work on pyroaurite-type materials which has recently been reviewed [73], In addition to precipitation methods, they have prepared the materials by mild oxidative hydrolysis of nickelates that were prepared by thermal methods similar to those used for the preparation of LiNiOz [74]. A cobalt-substituted material NaCoA ( Ni( A02) was prepared by the reaction of Na20, Co304 and NiO at 800 °C under a stream of oxygen. The material was then treated with a 10 molL-1 NaCIO +4 molL 1 KOH solution for 15h to form the oxidized y -oxyhydroxide. The pyroau-... 

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