In neutral and alkaline solutions

Amine oxides show either nonionic or cationic behavior in aqueous solution depending on pH. In acid solution the cationic form (R2N" OH) is observed (2) while in neutral and alkaline solution the nonionic form predorninates as the hydrate R NO H2O. The formation of an ionic species in the acidic pH range stabilizes the form generated by the most studied commercial amine oxide, dimethyldodecylamine oxide (6). 

Nickel alloys which rely on nobility for their corrosion resistance, viz. Ni-Cu and Ni-Mo alloys in acidic solution, do not usually pit in these circumstances. It should be noted, however, that the Ni-Cu alloy Monel 400 normally forms a protective oxide film in neutral and alkaline solutions, and this is of particular significance with regard to its corrosion resistance to... 

In neutral and alkaline solution, where the concentration of hydrogen ions is very low, the reaction switches to the reduction of water molecules ... 

The hydrogen evolution reaction (h.e.r.) is of particular importance in corrosion for a number of reasons. Firstly, the reduction of the HjO ion in acid solutions or the H2O molecule in neutral and alkaline solution is a common cathodic reaction for the corrosion of metals in acid, neutral and alkaline solutions the fact that iron will corrode in neutral water free from dissolved... 

A similar series of steps can be written for the h.e.r. in neutral and alkaline solutions, but the equations will then involve the water molecule, since the concentration of HjO in these solutions is too small for it to participate at a significant reaction rate. 

In neutral and alkaline solutions, the iso-Asp/Asp-peptide products were always formed in a ca. 3 1 ratio. In the Val-Xaa-Asn-Ser-Val series, the nature of the N-flanking residue had little effect on the rate of deamidation, regardless of size. However, the actual effect may have been partly masked by cleavage of the Asn-Ser bond (Sect. 6.3.2A), which proceeds at a rate ca. 10% that of deamidation. In the Val-Ser-Asn-Xaa-Val series, the nature of the C-flanking residue did have a major influence. As expected, the most unstable peptide was Val-Ser-Asn-Gly-Val (tll2 ca. 6 h at pH 7.3 and 60°). A second group of peptides had t1/2 values in the range of 25-75 h, which increased in the order Xaa=His[Pg.325]

In their reactions with organic compounds, OH is electrophilic and 0 is nucleophilic. Thus, OH behaves like H , readily adding to double bonds and aromatic rings, whereas O does not. Both forms of the radical abstract an H atom from C—H bonds and this can result in different products in neutral and alkaline solutions. This is exemplified by toluene, which reacts with OH and O as in reactions (50) and (51), respectively ... 

Th(IV) and U(IV) in neutral and alkaline solutions (the pH region of interest in performance assessment). Hence, the thermodynamic constants selected for the data base update (Hummel et al. 2002) do not refer to well-defined thorianite, Th02(cr), and uraninite, U02(cr), used in calorimetric measurements, but to the still poorly defined solids Th02(s) and U02(s) encountered in solubility studies at pH > 6 and pH > 5, respectively. Therefore, the thermodynamic constants selected in the data base update cannot be used to represent the widely varying solubilities of Th02 and U02 at pH < 5. 

The tetraphosphate anion is practically stable in neutral and alkaline solution at room temperature but at 65.9°C it is about half a power of ten less stable than the triphosphate anion over the whole pH range (61). Tetraphosphate has its maximum stability at 65.5°C at pH 10 and this is why it can be prepared from tetrametaphosphate at such temperatures. Its stability becomes smaller with decreasing pH. Apparently during the hydrolysis of an aqueous solution, which follows a first order law at constant pH, the tetraphosphate is cleaved initially exclusively at the end of the chain, to form mono- and tri-phosphate. 

AdoMet and AdoHcy are unstable in neutral and alkaline solution they must be kept acidified. 

Ascorbic acid is the main endogenous precursor of oxalic acid and in healthy persons up to 30% of urinary oxalate can originate from ascorbate. Ascorbate is extremely unstable in neutral and alkaline solutions and degrades to oxalate nonenzymatically [6]. Acidification to pH 1-2 is required to prevent deposition of insoluble Ca-oxalate. 

Although permonosulphuric acid is formed from acid-containing solutions of perdisulphuric acid, the latter is the more stable in neutral and alkaline solutions. 

Reduction of benzofuroxan (206)342 in neutral and alkaline solution first gives o-benzoquinonedioxime (207), which, as other oximes, is reduced with cleavage of the N—O bond to the diimine (208). The diimine then undergoes a two-electron reduction to o-phenylenediamine (209) or condenses with 209 to 2,3-diamino-9,l0-dihydrophenazine 210 [Eq. (120)]. 

A more recent paper by Cunningham and Schmir242 on the hydrolysis of 4-hydroxybutyranilide XL in neutral and alkaline solution suggests that intramolecular nucleophilic attack by the neighbouring hydroxyl group is followed by bifunctional catalysis by phosphate or bicarbonate buffers of the conversion of the tetrahedral intermediate to products. A quantitative comparison was made between the effects of buffer on the hydrolysis of 4-hydroxybutyranilide and on the hydrolysis of 2-phenyliminotetrahydrofuran, since both reactions proceed via identical intermediates. The mechanism suggested243 states that the cyclisation of the hydroxyanilide ion yields an addition intermediate whose anionic form may either cleave to products or revert to reactant and whose neutral form invariably gives aniline and butyrolactone, viz. 

A number of workers have investigated the oxidation of dextrins80 and starch81 with halogens in neutral and alkaline solutions and have reported the presence of significant amounts of anhydroglucuronic acid units in the products obtained, as determined by furfural formation. No attempt has been made, however, to develop a practical synthesis of D-glucuronic acid by this means. 

Microporous titanosilicate compounds have received significant consideration as ion exchangers ever since the introduction of ETS-4 and ETS-10 materials in 1989 [91,97-100], Some of these titanosilicates have proven to be good ion exchangers in neutral and alkaline solutions. For example, a potassium titanosilicate analogue of the mineral pharmacosiderite has been evaluated for the removal of cesium and strontium from various aqueous waste streams [91,101,102],... 

The complex is green (e = 306 M-1 cm.-1 at 700 nm.) and paramagnetic.4 7 From an x-ray crystallographic study,8 the 02 bridge is known to be cobalt atoms (Co—O—O angles 120°), and the 0—O distance is 1.32 A. The five atoms in the ring are very nearly coplanar. The complex is stable in acidic solutions, but in neutral and alkaline solutions it is reduced to the corresponding peroxo complex, with subsequent decomposition of the latter. Ferrous ion also reduces the complex, in the first place to the peroxo complex. 

Hydrogenolysis of carbon-sulfur bonds is a widely utilized reaction for removing sulfur from sulfur-containing organic compounds, and is known as desulfurization or hydrodesulfurization. Bougault et al. used Raney Ni for the first time for the desulfurization of aliphatic thioalcohols and disulfides in neutral and alkaline solution.126 Since then the reaction has been widely applied, for example, for organic syntheses, purification of solvents and substrates, structural studies, and determination of sulfur contents.127... 

Smith, F.G. and Kidd, D.J., 1949. Hematite-goethite relations in neutral and alkaline solutions under pressure. Am. Mineral., 34(5-6). 

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