Nitrate exchange reactions

Exchange of nitrate oxygen with water has been studied under conditions where it seems improbable that catalysis by nitrous acid contributes appreciably. The exchange is quite slow, and subject to chloride ion catalysis. The rate expression 

The energies of activation ( 1 and 2) re almost equal (22.1 and 21.8 kcal. mole respectively. The mechanism appears to involve S 2 reaction of H2O 

Oxygen exchange between hydrogen peroxide and nitrate ion probably involves nitrogen pentoxide, with formation of pernitric acid HOO.NO2. 

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Basic Extractants. Only long-chain quaternary ammonium salts, R3NCH3 X , ia which R represents Cg—0 2 groups and X nitrate or thiocyanate, are effectively used for REE separations (see Quaternary ammonium compounds). The extractant reacts with REE according to an anion-exchange reaction ... 

Another matter of concern in pyrotechnic formulations is the possibiHty of exchange reactions occurring between components. Addition of ammonium salts to compositions containing nitrate oxidizers can produce ammonium nitrate, a very hygroscopic material. The composition then becomes quite prone to pick up water and its performance deteriorates. The addition of an ammonium salt to a chlorate-based formulation can lead to the... 

In some cases only the first step is required, as with the formation of ethylam-monium nitrate. In many cases the desired cation is commercially available at reasonable cost, most commonly as a halide salt, thus requiring only the anion exchange reaction. Examples of these are the symmetrical tetraalkylammonium salts and trialkylsulfonium iodide. 

In nitrate media ( 6 Af), fluoride ion has a catalytic effect on the exchange reaction between Ce(IV) and Ce(III). Hornig and Libby have made a detailed study of this effect, over the range of added KF, 0 to 8.4 x 10 M, and have concluded that a pathway involving a monofluoro complex occurs, possibly involving a fluoride-bridged activated complex. 

Figure 3.12 Schematic representation of the dispersion of Zr02 particles and the extent to which the silica support is covered in three Zr02/Si02 catalysts prepared by impregnation with an aqueous zirconium nitrate solution, and one prepared via an exchange reaction of the support with zirconium ethoxide. The rectangles represent 100 nm2 of silica support area, and the circles represent a half-spherical particle of Zr02 seen from above. See Table 3.3 for corresponding numbers (adapted from Meijers et al. [33]).

Self-sustaining thermal decomposition of NPK fertilisers is apparently possible if crystalline potassium nitrate is present from a exchange reaction of ammonium nitrate [1], Almost pure fertiliser grades of ammonium nitrate are legally restricted in some countries because of its instability [2],... 

Pertechnetate in neutral and alkaline media can be extracted into solutions of tetra-alkylammonium iodides in benzene or chloroform. With tetra-n-heptylammo-nium iodide (7.5 x 10 M) in benzene distribution coefficients up to 18 can be obtained . A solution of fV-benzoyl-iV-phenylhydroxylamine (10 M) in chloroform can be used to extract pertechnetate from perchloric acid solution with a distribution coefficient of more than 200, if the concentration of HCIO is higher than 6 M The distribution of TcO between solutions of trilauryl-ammonium nitrate in o-xylene and aqueous solutions of nitrate has been measured. In 1 M (H, Li) NOj and 0.015 M trilaurylammonium nitrate the overall equilibrium constant has been found to be log K = 2.20 at 25 °C. The experiments support an ion exchange reaction . Pertechnetate can also be extracted with rhodamine-B hydrochloride into organic solvents. The extraction coefficient of Tc (VII) between nitrobenzene containing 0.005 %of rhodamine-B hydrochloride and aqueous alcoholic " Tc solution containing 0.0025 % of the hydrochloride, amounts to more than 5x10 at pH 4.7 . 

Base cations are mobilized by weathering and cation exchange reactions that neutralize acids in the watershed. They respond therefore indirectly to changes in sulphate and nitrate concentrations. In fact, if acid anion concentrations (mainly sulphate) decrease, base cations are also expected to decrease. However, in the last few years an increase of the occurrence of alkaline rain episodes (probably due to climatic effects) has been observed and it is likely that calcareous Saharan dust, rich in base cations, is responsible for it [27]. Accelerated weathering, resulting from recent climate warming may also contribute to higher base cation concentrations [28]. 

Kirkley MB, Gurney JJ, Otter ML, HiU SJ, Daniels LR (1991) The application of C-isotope measurements to the identification of the sources of C in diamonds. Appl Geochem 6 477 94 Kirshenbaum I, Smith JS, Crowell T, Graff J, McKee R (1947) Separation of the nitrogen isotopes by the exchange reaction between ammonia and solutions of ammonium nitrate. J Chem Phys 15 44(M46... 

Colorimetry. A variety of colorimetric techniques have been used to measure ions such as NH4, SO4-, and NO7 in ambient particles. For example, nitrate can be measured by reduction to nitrite using hydrazine in the presence of a copper catalyst, followed by its conversion to a colored azo dye, which can be measured by its absorbance at 524 nm (Mullin and Riley, 1955). Sulfate has been determined using an exchange reaction between sulfate and a barium-nitrosulfo-nazo(III) chelate in aqueous acetonitrile the chelate has an absorbance peak at 642 nm and hence the decrease in this peak can be followed as a measure of the amount of sulfate present that has exchanged with the chelate (Hoffer et al., 1979). Similarly, NH4 can be measured by the indophenol blue method (Weather-burn, 1967). 

The converse obviously applies to ammonium nitrate explosives, which must not contain any chlorates, since during storage a double exchange reaction may occur resulting in the formation of ammonium chlorate (p. 476, Vol. II), an unstable substance which decomposes spontaneously. A number of patents were taken out between 1880 and 1895, for explosives based on the use of ammonium chlorate or mixtures of ammonium nitrate with potassium or sodium chlorate. Many accidents which occurred through the spontaneous decomposition of these explosives proved the impossibility of using mixtures containing both chlorates and ammonium salts (Hantke [79]). 

From the middle of the nineteenth century potassium nitrate began to be manufactured from Chilian saltpetre containing 20-35% NaN03. The Chilian saltpetre was first refined to increase the content of NaN03 to 95% and afterwards subjected to the exchange reaction ... 

The hydrogen-isotope exchange reactions have already been discussed in previous sections. For various aromatic and heteroaromatic substrates, standard reaction rates in protodedeuteration and in nitration have been obtained. A plot of these shows a wide scatter. This means that there is no simple relation between these two measures for the susceptibility to electrophilic attack. No single reactivity index can be used as a measure to derive a unique order of the susceptibility of individual ring positions towards electrophilic attack (75TL1395). 

Ligand exchange reactions have been used to prepare mercury(II) trialkylarsine complexes.202 Reaction of AgN03-AsMe3 with mercury halides gave the mercury arsine and silver halide (equations 10 and 11). The silver nitrate complex was not characterized. 

This exchange reaction is conducted by the countercurrent flow of ammonia gas and ammonium nitrate solution (in water), The forward reaction is favored, resulting in the concentration of the nN in the ammonium nitrate in solution. The multistate conduct of this reaction that is necessary for effective operation is accomplished by arranging later stages in which the enriched ammonium nitrate solution is divided into two parts. One part is treated with caustic soda to displace the enriched NH3, which is then used in a second stage of the process with the other part of the NH4NO3 solution. Three or more stapes may thus be used, until the desired concentration of 15N has been effected. 

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