Ammonium ion, with

Reduction of dinitrogen oxide to ammonia (which gives the ammonium ion with the acid) ... 

These equations say that the Kh of an amine multiplied by the of the corresponding ammonium ion is equal to Kw, the ion-product constant for water (1.00 x 10 14). Thus, if we know Ka for an ammonium ion, we also know for the corresponding amine base because /stronger base has an ammonium ion with a larger p... 

Two types of compounds, crystalline and amorphous, can be precipitated from tantalum or niobium solutions by an initial ammonia solution containing ammonium ions, with an interface at about pH = 10. Such solutions are used for the stripping of tantalum or niobium from TBP extracts. In the case of pure fluorotantalic or fluoroniobic acids that result from the stripping process with water, the interface occurs at a lower pH level. 

R.M. Liu, B. Sun, D.J. Liu, and A.L. Sun, Flow injection gas-diffusion amperometric determination of trace amounts of ammonium ions with a cupric hexacyanoferrate. Talanta 43, 1049-1054 (1996). 

The induced circular dichroism and Cotton effect have been investigated for quaternary ammonium ions with N anchored on an asymmetric C, when hosted in calix[n]arene molecules (215, n = 4, 6, 8)430. 

It is also possible to determine ammonium ions with microorganisms other than nitrifiers, e.g., with Bacillus subtilis, Pseudomonas aeruginosa, and... 

Riedel K, Huth J, Kiihn M, Liebs P (1990) Amperometric determination of ammonium ions with a microbial sensor. J Chem Tech Biotechnol 47 109-116... 

Results of X-ray analysis of complexes of alkali- and ammonium ions with valinomycin /36-37 and the macrotetrolide antibiotics 2 to 63H 42 support this reasoning. For this idealized situation the Equations IIA to IIC (Table II) reduce to 33... 

We can draw schematically the interaction of ammonium ions with the anionic site of acetylcholinesterase in Fig. 5 based upon Eq. 36 since the informations for the steric and hydrophobic effects of substituents do not change practically even if la is used for the analysis 26). 

The data for ammonium chloride and bromide, treated similarly, lead to values of about 6 to 8 kcal/mole for the extra energy of interaction of the ammonium ion with the surrounding chloride and bromide ions. In these crystals each ammonium ion is surrounded by eight halide ions at cube corners. It can form hydrogen bonds with four, at tetrahedron corners, at a time. There... 

Free Energies and Interionic Distances for the Association of Ammonium Ion with the Anionic Sites of Cholinesterases Calculations are based on Equation (10)... 

Table 3.17 shows the complexation free energies for various ammonium ions with three corand receptors. It is immediately apparent that NH4+ is bound more strongly than either of its alkylated analogues, and methylammonium is bound more strongly than f-butylammonium, with a particularly large difference between NH4+ and CH3NH3+ complexes of 3.95 and 3.96 (10 kj mol-1). 

The corresponding dependence of cation complex stability on the anion differs profoundly from that of most other cation receptors such as cyclophanes or calix-arenes [16]. For these cation complex stability decreases on changing the anion from picrate through iodide to tosylate, a dependence that has been attributed to ion-pair aggregation in non-polar solvents. Because the interaction of quaternary ammonium ions with tosylate or iodide in chloroform is considerably stronger than with picrate, cation complexes in the presence of the latter anion are usually more stable. Only when iodide or tosylate cooperatively contributes to cation binding, as in 3 or in some recently described calixarene derivatives [17], is reversal of this order observed. 

By using the ammonium ions with four alkyl groups larger than the methyl group, the other types of silicate anions with cage-like structures are formed. For example, in tetraethylammonium (N+(C2H3) ) silicate aqueous solutions, the prismatic hexameric silicate anion (SigO g, prismatic hexamer) is formed (13,14,17,18). 

Reymond, J.L. and Chen, Y.W. (1995) Catalytic, enantioselective aldol reaction using antibodies against a quaternary ammonium ion with a primary amine cofactor. Tetrahedron Letters, 36, 2575-2578. 

Modin, R., Schill, G. Quantitative determinations by ion-pair extraction 1 ion-pairs of quaternary ammonium ions with organic anions. Acta Phram. Sue. 1967,4, 301-326. 

The apparent basicity anomaly of alkylamines can now be understood in terms of two opposing influences, one base-strengthening (due to increasing alkylation of the amine), and the other base-weakening (because of reduced solvation of the ammonium ions with increasing alkylation). For solvation effects on the basicities of alkyl amines in solvents other than water, see reference [243]. 

Dichloramine is an intermediate in the chlorination of NH3 in acidic solntion that leads to NCI3 (see Section 8.2.3), but the best synthesis is the chlorination of ammonium ions with hypochloric acid (ratio NTt4+ HOCl = 1 2) in dilute aqueous solution at pH values around 4. NH2CI is an intermediate in this reaction since the chlorination of NH2CI is slower than the chlorination of NH3. 

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