Ammonia proton

The Bronsted definitions of acids and bases are more general than the Arrhenius definitions they also apply to species in nonaqueous solvents and even to gas-phase reactions. For example, when pure acetic acid is added to liquid ammonia, proton transfer takes place and the following equilibrium is reached ... 

To express the relative strengths of an acid and its conjugate base (a conjugate acid-base pair ), we consider the special case of the ammonia proton transfer equilibrium, reaction C, for which the basicity constant was given earlier (Kb = [NH4+l[OH ]/ NH3]). Now let s consider the proton transfer equilibrium of ammonia s conjugate acid, NH4+, in water ... 

The occurrence of proton transfer reactions between Z)3+ ions and CHa, C2H, and NDZ, between methanium ions and NH, C2HG, CzD , and partially deuterated methanes, and between ammonium ions and ND has been demonstrated in irradiated mixtures of D2 and various reactants near 1 atm. pressure. The methanium ion-methane sequence proceeds without thermal activation between —78° and 25°C. The rate constants for the methanium ion-methane and ammonium ion-ammonia proton transfer reactions are 3.3 X 10 11 cc./molecule-sec. and 1.8 X 70 10 cc./molecule-sec., respectively, assuming equal neutralization rate constants for methanium and ammonium ions (7.6 X 10 4 cc./molecule-sec.). The methanium ion-methane and ammonium ion-ammonia sequences exhibit chain character. Ethanium ions do not undergo proton transfer with ethane. Propanium ions appear to dissociate even at total pressures near 1 atm. 

N(amine)/Co ratio which decreases from 2.7 to 0.7 as the solution pH is increased from 4 to 10. The N(amine)/Co ratio represents an upper limit for ammonia coordinated to cobalt Ill) for the adsorbed complex, since it is likely that ammonia coordinated to cobalt Ill) and ammonia sorbed on Na-birnessite would have very similar N Is binding energies, and thus, could not be easily distinguished. The greater surface concentration of protonated amine compared to non-protonated amine at low pHs indicates that the solution pH plays a role in determining the extent of ammonia protonation. However,... 

The label am indicates a species dissolved in liquid ammonia.) Protons can be transferred from acids to bases even in the gas phase, in the absence of a solvent. For example, hydrogen chloride and ammonia gases react by proton transfer when they mingle together. They produce a fine powder of ammonium chloride often seen coating surfaces in chemical laboratories ... 

Consider the ammonia proton transfer equilibrium, reaction C, for which [NH4+][OH ] b INH,]... 

DeNOx reaction involves a strongly adsorbed NH3 species and a gaseous or weakly adsorbed NO species, but differ in their identification of the nature of the adsorbed reactive ammonia (protonated ammonia vs. molecularly coordinated ammonia), of the active sites (Br0nsted vs. Lewis sites) and of the associated reaction intermediates [16,17]. Concerning the mechanism of SO2 oxidation over DeNOxing catalysts, few systematic studies have been reported up to now. Svachula et al. [18] have proposed a redox reaction mechanism based on the assumption of surface vanadyl sulfates as the active sites, in line with the consolidated picture of active sites in commercial sulfuric acid catalysts [19]. Such a mechanism can explain the observed effects of operating conditions, feed composition, and catalyst design parameters on the SO2 SO3 reaction over metal-oxide-based SCR catalysts. 

Anodic oxidation of primary amines at platinum or carbon electrodes is not of significant preparative interest. The common products in acetonitrile are the aldehydes VI, NH4, nitrogen from the oxidation of ammonia, protonated starting material, and hydrocarbons... 

Alkali metals arc usually dissolved or suspended in liquid ammonia or low molecular weight aliphatic amines, hexamethylphosphoric triamide or alcohols. Often these reductions are carried out in the presence of a cosolvent, such as diethyl ether, tetrahydrofuran or 1,2-dimethoxyethane, in order to increase the solubility of the ketone in the reaction mixture. Ethanol (pKa 15.9), 2-propanol (pKa 16.5), 2-methyl-2-propanol (p a 18), water (pK 15.7) and ammonium chloride (pKa 9.2) arc the usual proton donors. Thus, ammonium chloride is the strongest acid that can be incorporated into liquid ammonia. Proton donors are present in the reaction medium from the beginning, added concurrently with the ketone, or are added during product isolation (" aprotic reduction ). 

Base accepts a proton from water (Figure 18.8B). In an aqueous solution of ammonia, proton transfer also occurs. An H from H2O attaches to the N atom s lone pair, forming NH4. Having transferred an H", the H2O becomes an OH ion ... 

Moreover, some driving force will be provided if the [A-acceptor] is either especially stable (like the ethyl 9-anthroate case) or removed from equilibrium by ammonia protonation (like the naphthalene case). 

Solution Since the reaction is carried out in liquid ammonia, proton transfer from the solvent (ammonia) is the possible termination reaction. The relevant carbanions are... 

NH4 ions formed as a result of ammonia protonation by acidic hydroxyls ... 

Ammonia is removed by a IM H2SO4 water solution scrubber the liquid solution entering from the top of the tower (a SCDS column settled as packed column mass transfer simulation model) is continuously fed by a make-up quantity corresponding to the amount needed for the ammonia removal. At the bottom of the column gaseous ammonia enters at T = 95°C, it dissolves into the acid solution, diffuses and rapidly reacts with the H+ ions via ammonia protonation following thermodynamics of electrolyte non-random two liquid (Electrolyte NRTL) approach. 

Due to the valency IV of titanium, its substitution for Si does not cause any charge unbalance. Accordingly, no Brpnsted acidity is formed on Ti silicalite, as deduced, for example, by the lack of ammonia protonation [73], although an enhancement of the acidity of the silanols does possibly occur (Figure 9.4). Some debate exists on whether framework Ti" + ions can actually act as Lewis acid sites at the gas-solid interface. According to Manoilova et al. [258] CO... 

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