Hydroxide ions, generation

To abstract a proton is to remove only the proton. The substantial extent of dissociation in Equation (6.11) helps explain why aqueous ammonia is more properly called ammonium hydroxide , NH4OH. We generate the solvated hydroxide ion OH (aq) by abstracting a proton from water. The OH (aq) ion in Equation (6.11) is chemically and physically identical to the solvated hydroxide ion generated by dissolving NaOH or KOH in water. 

As we saw above, chlorine forms hypochlorous acid, HOCI. The hydroxide ions generated from urea react with the hypochlorous acid in a typical acid-base reaction,... 

A simple and effective way of incorporating such a cation-exchange material into the interfacial region would be to apply it to the metal surface as a final pretreatment process. This way the released hydrogen ions would be present in the immediate vicinity of the hydroxide ion generation sites. Therefore, the hydroxide ions could be promptly neutralized and the hydrolysis of the epoxy coating by strong alkali minimized 91>. 

There may also be cases in which charge transfer may appear to be but is not in fact really responsible for radical ion formation, so that seeking the two ion radicals corresponding to a charge-transfer complex is in vain. For example, reaction between tetracyano-ethylene and amines often leads to the TCNE - but no sign of the amine cation radical is obtained. When pyridine is used, a charge-transfer band is detectable in the ultraviolet (and is probably from an outer complex), but the reaction which leads to TCNE - is not electron donation by pyridine but the very complex reaction of hydroxide ion (generated by pyridine) with TCNE (Shine and... 

Bolh weak and strong acids can be titrated with a high degree of accuracy using hydroxide ions generated at a cathode by the reaction... 

Figure 14 Catalytic mechanisms proposed for the purple acid phosphatases (1) attack of a terminal hydroxide on the Fe on a monodentate phosphate ester substrate coordinated to the divalent metal site (2) attack of the bridging hydroxide on a bridging phosphate ester (3) attack of a hydroxide ion generated in the second coordination sphere of the Fe on a monodentate phosphate ester.

A synthesis of pontevedrine (52) has been accomplished. Irradiation of the bromo-pyridone (51) in the presence of oxygen and hydroxide ion generated... 

In this process, a cation-exchange membrane such as perfluorocarboxylic acid membrane is used to partition the anode from the cathode assembly. The cation-exchange membrane allows only the hydrated positive ions, the sodium and hydronium ions, into the cathode compartment. The membrane also prevents the hydroxide ions generated in the cathode or chlorine ions in the anode from migrating across. 

Under the influence of the electric held, the niunber of hydronium ions generated at the anode is the same as that of hydroxide ions generated at the cathode, so the flow of hydronium ions in one direction is in equilibrium with the flow of KOH into the other direction. Thus, the boundary layer between hydronium and potassium ions is spatially fixed. If the applied current and, consequently, the flow of hydronium ions to the cathode are changed, the flow of hydroxide ions to the anode is changed in the same way. Thus, the electrochemical split of water is the motor for this circulating pool of potassium ions. 

A known volume of seawater is acidified and the carbon dioxide produced is stripped out of the sample by an inert gas. The gas is bubbled through a reagent containing ethanol-amine, which reacts with the carbon dionde to produce hydroxyethylcarbamic add (Eq. (8-26)). The latter is coulometrically titrated by the hydroxide ions generated at the cathode (Eq. (8-27)), and the pH in the reagent solution is monitored colorimetrically through the indicator thymolphthalein. At the anode silver is oddised (Eq. (8-28)). The amount of electrons produced corresponds to the amount of carbon dioxide in the sample and can thus be converted into concentration by dividing by the sample volume. 

One of the major possible drawbacks is that EDI is susceptible to precipitation of bivalent metal hydroxides as a result of metal ions reacting with hydroxide ions generated within the EDI apparatus. The implementation of EDI in water treatment has been greatly limited by this drawback (Feng et al, 2007). Therefore, possible integrations of ED with other processes (other than EDI) are emerging (Abou-Shady et al, 2012 Nataraj et al, 2007 Tran et al, 2012). 

The hydroxide ion leaves in the second step of this E2 mechanism. This step might be r arded as unusual because we know that the hydroxide ion is not a good leaving group. However, in this case, the loss of a hydroxide ion generates a conjugated unsaturated aldehyde. The resonance stabilization of conjugated multiple bonds makes this step exothermic. 

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