Ammonium salts structure

Platinum, hexachloro-ammonium salt structure, 1,16 Platinum, tetraammine-amminctrichloroplatinate polymerization isomerism, 1,187 dichloride structure, l, 16... 

Vanadium. oxybis[oxybis(dioxygen)-ammonium salt structure, 1, 61... 

Alpha-sulfo-omega-(dodecyloxy )-poly(oxy-1,2-ethanediyl) ammonium salt Structural formula CHjfCHjfioCHjfOCHjCHjfjOSOjNH ... 

The first step of the reaction involves the formation of the S-C bond with the elimination of a molecule of ammonium salt. The fact that it has been possible to isolate the acyclic intermediate (176), R = Me or Ph, would confirm this hypothesis, particularly when the reaction is carried out for a short time in the cold in ethereal solution (27, 82). These intermediates (176) can be cyclized quantitatively on standing or on being treated by hydrochloric acid. However, no evidence has been advanced concerning their structures. 

Physostigmme an alkaloid obtained from a West African plant is used in the treatment of glaucoma Treatment of physostigmme with methyl iodide gives a quaternary ammonium salt What IS the structure of this salt" ... 

More recently, Johnson and Sutherland have used bridged monoazacrowns as host molecules for bis-ammonium salts. The intramolecular bis-crown diammonium complex formed when the size relationships are appropriate is shown below as structure 8. 

In other sections in this chapter, we have referred to a variety of macropolycyclic structures which are more elaborate than the simple three-stranded bicyclic cryptands. This includes bridged double-macrocycles " , in-out bicyclic amines and the macrotricyclic quaternary ammonium salts of Schmidtchen. In addition to these, there are two other types of compounds which deserve special note. The first of these is a stacked twin-ring cryptand, but it is a hybrid molecule rather than a double-cryptand . The species shown below as 20 is a crowned porphyrin, and was designed to provide a pair of metal cation binding sites similar to those which might be available in natural biological systems . 

It has long been known that quaternary ammonium salts can exert a curare-like action, and in recent years much attention has been given to the synthesis and pharmacological testing of such products work on this subject up to 1936 has been reviewed by Ing, and more recently a theoretical discussion of the relationship between structure and action in drugs of this type has been provided by Holmes, Jenden and Taylor.Chase, Lehmann and Yonkmann have compared the action of quaternary salts of quinine with that of -erythroidine hydrochloride and of dihydro- -erythroidine hydrobromide. Quinine ethochloride shows marked curariform action of short duration. ... 

Ion exchange on an acid column yields the crystalline dihydrate" H4P2O6.2H2O which is actually the hydroxonium salt of the dihydrogen hypophosphate anion [H30lJl(II0)P(0)2--P(0)2(0H)] " it is isostructural with the corresponding ammonium salt for which X-ray diffraction studies establish the staggered structure shown. 

The structure, and the mechanism of the chemical transformations, of the pseudo ammonium bases which can be obtained from heterocyclic quaternary ammonium salts has been one of the most discussed phenomena in theoretical organic chemistry since the first publication in this field by Claus and Himmelmann. These questions have still not been finally decided. 

II. The Structure of Bases Obtained from Heterocyclic Quaternary Ammonium Salts... 

In the case of the bases derived from quaternary heterocyclic ammonium salts, the carbinolamines (5) can react as cyclic aldehyde-ammonias with many reagents with which the amino-aldehyde (7) could react. However, reactions of the carbinolamines which are not characteristic of amino-aldehydes are also known. Carbinolamines can easily be reconverted into the quaternary salts by the action of dilute acids, and they form alkyl ethers very easily with alcohols. If these last reactions do not occur, then this is convincing evidence for the base possessing the amino-aldehyde structure. However, if these reactions do occur this does not provide unambiguous confirmation of the carbinolamine structure. They are also given by the bi-molecular ethers (8), and, in the case of a tautomeric equilibrium... 

Qiana, structure of, 836 Quantum mechanical model, 4-6 Quartet (NMR), 460 Quaternary ammonium salt. 917 Hofmann elimination and, 936-937... 

Kekule (1866, vol. II, p. 716) realized that the diazo compounds were structurally analogous to their most important derivatives, the azo compounds, and he therefore described their constitution with the formula C6H5-N = N-X. The fact that the diazo compounds are much less stable than the azo species was thought to detract from Kelule s formulation. Blomstrand (1869, 1875) proposed the structure C6H5 — N — X and, in analogy to the ammonium salts, the name azoammonium . 

Determination of the influence of crystal structure and reactant environment on deammination and dehydration processes is complicated by the several solid phase transformations that are a characteristic feature of many ammonium salts. Sublimation and/or melting may also occur. Deammination and dehydration steps are generally reversible. At high temperatures, however, particularly in the presence of a residual oxide... 

Small amounts (<3.5%) of ammonium salts markedly accelerate [970] the dehydration of Na2HP04 12 H20 to Na2P207. This is attributed to an increase in the concentration of delocalized protons in the structure, as a consequence of the proton donor properties of NH4, and this promotes dehydration. 

Ammonium salts of the zeolites differ from most of the compounds containing this cation discussed above, in that the anion is a stable network of A104 and Si04 tetrahedra with acid groups situated within the regular channels and pore structure. The removal of ammonia (and water) from such structures has been of interest owing to the catalytic activity of the decomposition product. It is believed [1006] that the first step in deammination is proton transfer (as in the decomposition of many other ammonium salts) from NH4 to the (Al, Si)04 network with —OH production. This reaction is 90% complete by 673 K [1007] and water is lost by condensation of the —OH groups (773—1173 K). The rate of ammonia evolution and the nature of the residual product depend to some extent on reactant disposition [1006,1008]. 

Trimerization to isocyanurates (Scheme 4.14) is commonly used as a method for modifying the physical properties of both raw materials and polymeric products. For example, trimerization of aliphatic isocyanates is used to increase monomer functionality and reduce volatility (Section 4.2.2). This is especially important in raw materials for coatings applications where higher functionality is needed for crosslinking and decreased volatility is essential to reduce VOCs. Another application is rigid isocyanurate foams for insulation and structural support (Section 4.1.1) where trimerization is utilized to increase thermal stability and reduce combustibility and smoke formation. Effective trimer catalysts include potassium salts of carboxylic acids and quaternary ammonium salts for aliphatic isocyanates and Mannich bases for aromatic isocyanates. 

The higher solubility of several quaternary ammonium salts of glyphosate in polar aprotic organic solvents such as acetonitrile was discovered (2), which permitted their reaction in solution with various alkyl halides. For example, GLY(n-Bu4N)2H reacted with either o-xylylene dichloride or 1,5-dibromopentane to produce the interesting quaternary glyphosate derivatives 81 and 82, whose structures have been confirmed by x-ray analysis (2). 

The XRD patterns of alkaline or ammonium salts of H3PW12O40 or H4SiWi2O40 were typical of the cubic structure. No additionnal XRD peak was observed indicating the absence of other phases. The same unit cell was measured for the different Cs salts of H3PW12O40 (ao = 1.184 nm) and for the Cs salt of H4SiWi204o ( ag = 1.178 nm), in agreement with the value reported in the literature for the neutral salts [9,11] whatever be the Cs content. 

Results indicate that the effectiveness of quaternary ammonium salt polymers in stabilizing swelling clays and mineral fine particles is dependent on monomer chemical structure and polymer molecular weight. Long flexible pendant sidechains containing quaternary nitrogen atoms appear to be required for these polymers to function as mineral fine particle stabilizers. 

Tetrachlorooxotechnetate(V) results from action of cone. HC1 on perteeh-netate at ambient temperatures and is preferably isolated as the tetrabutyl-ammonium salt [19]. Tetrabromooxotechnetate(V) was similarly obtained with hydrobromic add at 0 °C [8]. The molecular structures of both compounds are reported in [20,21]. The analogous iodo complex, tetraiodooxotechnetate(V), was synthesized by ligand exchange of the chloro compound with sodium iodide in acetone [22]. However, it suffers from considerable decomposition during isolation. 

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