Normal ammonium fluoride

Two well-known salts of ammonia (qv) are the normal ammonium fluoride [12125-01 -8] NH F, and ammonium bifluoride [1341 -49-7] NH4HF2 the latter is sometimes named ammonium acid, or hydrogen difluoride. Much of the commercial interest in the ammonium fluorides stems from their chemical reactivity as less ha2ardous substitutes for hydrofluoric acid. 

Synonyms neutral ammonium fluoride normal ammonium fluoride... 

Chemical Designations - Synonyms Neutral Ammonium Fluoride Chemical Formula NH F. Observable Characteristics - Physical State (as normally shipped) Solid Color White Odor None. Physical and Chemical Properties - Physical State at 15 X and I atm. Solid Molecular Weight 37.04 Boiling Point at I atm. Not pertinent (decomposes) Freezing Point Not pertinent Critical Temperature Not pertinent Critical Pressure Not pertinent ecific Gravity 1.32 at 25°C (solid) Vapor (Gas) Density Not pertinent Ratio of Specific Heats of Vapor (Gas) Not pertinent Latent Heat of Vaporization Not pertinent Heat cf Combustion Not pertinent Heat of Decomposition Not pertinent. 

The two components of ammonium fluoride behave in very much the same way as do donor and acceptor impurities in electronic semiconductors, leading to more or less complete compensation. This behaviour is illustrated, as far as static conductivity is concerned, by the careful study of Levi et al. (1963) in which the ratio of hydrogen fluoride to ammonia concentrations was varied over a wide range. The experimental results are shown in fig. 9.9 and illustrate the expected behaviour. This can be calculated by the normal chemical methods used for a solution containing a weak acid and a weak base but, to obtain reasonable agreement with experi-... 

The synthesis of polyhalide salts, R4NX , used in electrophilic substitution reactions, are described in Chapter 2 and H-bonded complexed salts with the free acid, R4NHX2, which are used for example in acid-catalysed cleavage reactions and in electrophilic addition reactions with alkenes, are often produced in situ [33], although the fluorides are obtained by modification of method I.I.I.B. [19, 34], The in situ formation of such salts can inhibit normal nucleophilic reactions [35, 36]. Quaternary ammonium chlorometallates have been synthesized from quaternary ammonium chlorides and transition metal chlorides, such as IrClj and PtCl4, and are highly efficient catalysts for phase-transfer reactions and for metal complex promoted reactions [37]. 

Examples of the Michael-type addition of carbanions, derived from activated methylene compounds, with electron-deficient alkenes under phase-transfer catalytic conditions have been reported [e.g. 1-17] (Table 6.16). Although the basic conditions are normally provided by sodium hydroxide or potassium carbonate, fluoride and cyanide salts have also been used [e.g. 1, 12-14]. Soliddiquid two-phase systems, with or without added organic solvent [e.g. 15-18] and polymer-supported catalysts [11] have been employed, as well as normal liquiddiquid conditions. The micellar ammonium catalysts have also been used, e.g. for the condensation of p-dicarbonyl compounds with but-3-en-2-one [19], and they are reported to be superior to tetra-n-butylammonium bromide at low base concentrations. 

Other ingredients that may be found in smokeless powders include camphor, carbazole, cresol, diethyleneglycoldinitrate (DEGDN), dimethylse-bacate, dinitrocresol, di-normal-propyl adipate, 2.4-dinitrodiphenylamine, PETN, TNT, RDX, acaroid resin, gum arabic, synthetic resins, aluminum, ammonium chlorate/oxalate/perchlorate, pentaerythritol dioleate, oxamide, lead carbonate/salicylate/stearate, magnesium oxide, sodium aluminum fluoride, sodium carbonate/bicarbonate, petrolatum, dioctylphthalate, stannic oxide, potassium cyrolate, triphenyl bismuth. 

Sufficient ammonium iron fluoride salt was added to the NH4Y to replace 55% of the framework A1 in the Y zeolite. The LZ-224 product contained 16.9 wt.% Fe203. The product was 48% dealuminated with an apparent value of 95% substitution of Fe into the dealuminated sites. This value is inflated due to the fact that iron Is also exchanged into the normal cation positions as well. The color of the LZ-224 product was brown, indicating the presence of the Fe cations. The normal cation equivalent,... 

Ammonium hydrogen fluoride, NH4F,HF.—Evaporation of a solution of the normal salt at a temperature between 36° and 40° C. expels ammonia, the primary salt crystallizing out. It can also be prepared by the action of ammonia on a solution of hydrogen fluoride, a small proportion of ammonium sulphide or carbonate being added.13 It forms colourless rhombic prisms, readily soluble in water,6 with a density of 1-21114 at 12° C. 

Fluoride was found to have a similar, but less pronounced, effect on the MW distribution of polymers made with Cr/silica. An example is shown in Figure 139. Cr/silica catalyst, with and without ammonium bifluoride, was activated at 400 °C and tested for polymerization activity. The addition of fluoride was again found to remove sites producing low-MW polymer. The difference curve is shown, obtained by subtracting the two parent curves after they were normalized by catalyst activity. The addition of fluoride to the catalyst caused a loss of low-MW polymer (centered at about 103 5 or 3200 g mol-1), and a gain of higher-MW... 

Volatile metal halides, usually chlorides and fluorides, also form the heart of several processes used to produce surface layers, rich in aluminium, chromium, or silicon, or combinations of these. In these processes, the workpiece to be coated is buried in a powder bed and heated to reaction temperature. The bed consists of a mixture of inert alumina filler, a master alloy powder that contains the aluminium, etc., and an activator such as ammonium chloride. Basically, at about 630°C, the activator volatilizes and the aluminium chloride vapour reacts with the master alloy to produce a volatile aluminium chloride, which then reacts with the workpiece surface to deposit aluminium. The deposited aluminium proceeds to diffuse into the surface layers of the workpiece to produce a diffusion coating. The process is driven basically by the difference in aluminium activity between the master alloy and the worlqtiece. These processes are well documented in principle, but their execution to provide reproducible and reliable results still involves considerable experience, or rule of thumb. These processes will be described in detail in Chapter 10. Finally, a chlorination treatment is used to remove tin from tin-plated steel. This uses a normally deleterious reaction to advantage and profit in the recovery of both tin and steel for recycling. Fluorination is used in the manufacture of polymers and fluorocarbon consequently, materials suitable for construction of these plants must be resistant to fluorine attack. 

Body fluids are complicated mixtures whose inorganic electrolyte composition in plasma and muscle cells is normally fairly constant, but which may show considerable variations in gastric and pancreatic juices, sweat, saliva and urine. Ion-selective electrodes are the only devices capable of measuring the important normal ions and dissolved gases in fluids and they have proved particularly useful for medical, biochemical and physiological investigations of calcium, potassium, sodium, ammonium, chloride and fluoride. To a lesser extent, the electrodes have been used for bromide, iodide, lead, carbon dioxide, enzymes, proteins and in metal—nucleotide systems. 

The advantage of discrete analyzers is that sample crossover in the system itself is the lowest possible. Volumes of 75 pi of reagent and sample volumes as large as 100 pi are sufficient. In an automated system with a throughput of 200 determinations per hour in the same sample 6 to 10 components (such as ammonium, alkalinity, aluminum, boron, bromide, calcium, chloride, chromium(VI), cyanide, fluoride, iron, magnesium, nitrate, nitrite, phosphate, etc.) can be determined. In discrete analyzers normally conventional spectrophotometric methods are used. These methods are prone to interference of the matrix of the sample. As a good concept for interference studies still is not available, interferences are as yet not sufficiently studied systematically even for routine analyses. 

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