Salts alkylammonium

Alkylammonium salts are typical cationic surfactants. The adsorption and the properties of the monolayers formed by these salts at water-air and water-oil interfaces have frequently been investigated [11, 24, 36, 37, 46, 63]. Mostly the adsorption of alkylammonium cations from the aqueous phase was studied. Special attention was paid to the relation between the structure of alkylammonium cations, their surface-active properties and the monolayer structure. Less attention was given to the influence of the anion nature of alkylammonium salt adsorption from the non-aqueous phase and competitive adsorption of counterions in cationic monolayers at the water-oil interface, although these problems are vital for understanding the mechanism of liquid ion-exchange extraction. 

The most detailed study of the interaction between inorganic ions and insoluble cationic monolayers was conducted by Goddard et al. [69-72]. A specific interaction was observed between anions and the monolayer of alkylammonium cations. Its value depends on the nature of the anion with the exception of the ion of fluorine. Only in the case when F is taken as a counterion, the dependence of the surface pressure on the area per molecule in the monolayer obeys the Davis equation of state for the charged monolayers. As the counterion radius decreases, the surface pressure on a given area 

The surface activity of the soluble cationic surfactants at the water-air and water-nonpolar oil interfaces is mainly determined by the structure of the hydrocarbon chains. The work of adsorption in the homologous series of alkylammonium salts obeys the Traube rule [24,46,63,76]. Shipunov studied adsorption in the homologous series of tetra-alkylammonium chlorides at the water-heptane interface. He established that the work of adsorption is proportional not to the number of methyl groups in the 

The nature of the anion also affects the surface activity of the water-soluble cationic surfactants. The surface activity of tetra-butylammonium salts at the water-air and water-hexane interfaces reduces in the order iodiode bromide chloride [77,78]. Boguslavsky et al. reported that the adsorption equihbrium constant and the adsorption at the water-octane interface are higher for tetra-alkylammonium bromides as compared to chlorides [76,79]. The influence of the counterions on the adsorption of alkylpyridinium salts at the water-air interface was studied. It was estab-hshed that the salts lowered the surface tension in the sequence perchlorate thiocyanate iodide bromide chloride [80-83]. The anion influence on the work of adsorption was found to increase with the growth of the concentration of the surface-active salt [83]. 

The anion series in the order of their influence on the surface activity of cationic surfactants and on the properties of insoluble monolayers coincide with the lyotropic series. The anion nature is manifested in the specific interaction with cationic surfactants with the formation of ionic pairs or in the anion penetration into the adsorption monolayers. Apparently, charge transfer complexes are frequently formed at the water-air and water-oil interfaces between the adsorbed cations and anions. Mukerjee and Ray estabhshed that these complexes exist in ionic pairs, between Br or J anions and dodecylpyridine ions in chloroform, and also on the micelle surface formed by the same cations in water [84-86]. The data on the ionic pair structure at the interface can be obtained by spectral study of monolayers and solutions of ionogenic surfactants in nonpolar solvents. According to Goddard, the investigation on the mixed monolayers formed by the surface-active anions and quaternary ammonium compounds will enable us to better understand the specific properties of the interaction between the adsorbed ions [72]. 

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The direction of electroosmotic flow and, therefore, the order of elution in CZE can be reversed. This is accomplished by adding an alkylammonium salt to the buffer solution. As shown in Figure 12.45, the positively charged end of the alkylammonium ion binds to the negatively charged silanate ions on the capillary s walls. The alkylammonium ion s tail is hydrophobic and associates with the tail of another alkylammonium ion. The result is a layer of positive charges to which anions in the buffer solution are attracted. The migration of these solvated anions toward... 

Catalyst Cation. The logarithms of extraction constants for symmetrical tetra- -alkylammonium salts (log rise by ca 0.54 per added C atom. Although absolute numerical values for extraction coefficients are vastly different in various solvents and for various anions, this relation holds as a first approximation for most solvent—water combinations tested and for many anions. It is important to note, however, that the lipophilicity of phenyl and benzyl groups carrying ammonium salts is much lower than the number of C atoms might suggest. Benzyl is extracted between / -propyl and -butyl. The extraction constants of tetra- -butylammonium salts are about 140 times larger than the constants for tetra- -propylammonium salts of the same anion in the same solvent—water system. 

Ishikawa, M., Morita, M., lhara, M. and Matsuda, Y., Electric double layer capacitor composed of activated carbon fiber cloth electrodes and solid polymer electrolytes containing alkylammonium salt, J. Electrochem. Soc., 1994, 141(7), 1730 1734. 

Whilst some organic compounds can be investigated in aqueous solution, it is frequently necessary to add an organic solvent to improve the solubility suitable water-miscible solvents include ethanol, methanol, ethane-1,2-diol, dioxan, acetonitrile and acetic (ethanoic) acid. In some cases a purely organic solvent must be used and anhydrous materials such as acetic acid, formamide and diethylamine have been employed suitable supporting electrolytes in these solvents include lithium perchlorate and tetra-alkylammonium salts R4NX (R = ethyl or butyl X = iodide or perchlorate). 

The sulfate radical anion is formed by thermal, photochemical or redox decomposition of persulfate salts (41, sec 3.3.2.6.1). Consequently, it is usually used in aqueous solution. However, crown ether complexes or alkylammonium salts may be used to generate the sulfate radical anion in organic solution (see 3.3.2.6.1). 

Using this approach, calculations can be made of volumetric, entropic and energy parameters taking account of the effect of overlapping cospheres. Some indication of the organization in the solution is also possible. The properties of a number of concentrated salt solutions have been analysed by this procedure, including simple 1 1 salts, alkaline earth salts and alkylammonium salts. 

Quaternary alkylammonium salts are generally water-soluble surfactants. The sol-gel-derived anion-sensing membranes encapsulating a quaternary alkylammonium salt, especially with high contents, are easy to deteriorate due to the exudation of the cationic site from the membrane to aqueous sample phases. Moreover, another issue concerning the dispersibility of ammonium salts in sol-gel-derived membranes may happen when high... 

The derivative-forming process in pyrolytic alkylation involves two sequential reactions deprotonation of the acidic substrate in aqueous solution by the strongly basic tetra-alkylammonium ion and the thermal decomposition of the quaternary M-alkylammonium salt formed to give a tertiary amine and alkyl derivative. For some weak acids both processes may occur virtually simultaneously in the injector oven of the gas chromatograph. 

In many other situations of donor-acceptor solutes in aprotic solvents, such as quaternary alkylammonium salts (R4NX), a UV absorption shift to higher wavelength has proved the occurrence of simple cation-anion ion... 

Solutions of the alkylammonium salts of Cl , Br , r in acetonitrile show no visible absorptions beyond 300 nm. The aromatic it-acceptor, tetracyanopy-razine (TCP) is characterized by strong absorptions in the 220-300 nm range and a shoulder at 350 nm. However, the electronic spectrum of a mixture of the bromide salt and TCP reveals a new absorption band at Xct = 400 nm... 

X-ray structural information on halide binding to neutral organic it-receptors is limited to a few recent reports [23,24,62,89-91 ]2. In fact, the slow diffusion of hexane into a dichloromethane solutions of tetracyanopyrazine containing the alkylammonium salts of either chloride, bromide or iodide affords yellow to red crystals with UV-Vis absorptions closely resembling the elec-... 

In a similar manner, the diffusion of hexane into dichloromethane solutions containing mixtures of the alkylammonium salts of bromide and the olefinic acceptors o-CA and TCNE result in the formation of brown-red crystals [23]. X-ray analysis reveals the (1 1) complex of bromide with o-CA, in which the anion is located over the center of the C - C bond of the acceptor moiety (Fig. 15b) and Br - C contacts are shortened by as much as 0.6 A relative to the sum of van der Waals radii (Table 3). In bromide complexes with TCNE, the location of the anion relative to the acceptor is variable. In fact, a 2 1 complex [(Br )2,TCNE] is isolated in which both anions reside over the olefinic bond when the tetraethylammonium salt of bromide is used. In comparison, if the tetrapropyl- or tetrabutylammonium salts of the same anion are employed, the (1 1) complexes [Br ,TCNE] are formed in which the bromide donors are shifted toward the cyano substituents (Fig. 15a). In both cases however, the short intermolecular separations that are characteris-... 

Also of importance for analytical and structural studies are the complexes with alkylammonium salts, widely used under selective conditions of critical electrolyte concentrations (see Section III). 

Certain long-chain alkylammonium salts, notably tricaprylmethyl-ammonium chloride (Aliquat 336-S) and tri-Ao-octylamine hydrochloride (TIOA) are liquids, sometimes referred to as liquid anion exchangers, which can form extractable ion pairs or aggregates with anionic metal complexes in the... 

Additives such as acids, bases or tetra-alkylammonium salts ... 

In the preceding section it was shown that the stability of crown-ether complexes with alkylammonium salts depends on the relationship between the structures of the crown ethers and the ammonium ions. How critically this relationship determines the complex stability will become clear in this section, which deals with the discrimination between the two enantiomers of racemic salts by chiral macrocyclic ligands. 

Palladium clusters [51], solubilized by tetra-n-alkylammonium salts, are effective in the Suzuki coupling of phenylborinic acid with bromoarenes to produce biaryls... 

Many examples of the phase-transfer catalysed epoxidation of a,(3-unsaturated carbonyl compounds using sodium hypochlorite have been reported [e.g. 7-10]. The addition of transition metal complexes also aids the reaction [11], but advantages in reaction time or yields are relatively insignificant, whereas the use of hexaethyl-guanidinium chloride, instead of a tetra-alkylammonium salt, enhances the rate of epoxidation while retaining the high yields (>95%) [10]. Intermediate (3-haloalkanols are readily converted into the oxiranes under basic conditions in the presence of benzyltriethylammonium chloride [12]. 

Bulky quaternary ammonium salts promote the ruthenium-catalysed oxidation of anilines by hydrogen peroxide to nitrobenzenes [25]. In the absence of the ammonium salt, the major product is the azoxybenzene, whereas lower molecular weight tetra-alkylammonium salts produce a mixture of products. 

Similarly, reactive oxide mixtures are also used to synthesize aluminophosphate molecular sieves, usually starting from phosphoric acid along with the addition of alumina and silica sources analogous to those used in zeolite synthesis with a notable exception alkylammonium salts and amines were ultilized in structure-direchng and space filling to the exclusion of alkali hydroxide solutions and alkali metal salts. 

As a rather strongly hydrophilic anion, nitrate requires an ISE membrane containing a strongly hydrophobic cation, as described on p. 169. This function was fulfilled in the first nitrate electrode from Orion Research by cation V [180] in nitro-p-cymene 5. The electrode can be used in the pH range 4-7. In other commercial electrodes, the ion-exchanger ion is a tetra-alkylammonium salt, for example in the electrode from Coming Co., substance XIII in solvent 6 [27]. An ISE with a renewable membrane surface was found to be very useful (see section 4.1 and fig. 4.4), in which the ion-exchanger solution contains the nitrate of crystal violet VII dissolved in nitrobenzene [191]. The NOj ISE also responds to nitrites that can be removed by addition of aminosulphonic acid. 

Chiral ligands XXXII and XXXIII are marked by slight but clear selectivity in ISEs with respect to chiral antipodes in tetra-alkylammonium salts [175, 209]. 

It is interesting to observe that alkylammonium salts, alkylarylsnlfonic acids, hydroxyoximes, aUcylphosphoric acids, and alkylhydroxamic acids, as well as nentral extractants such as crown ethers and tributyl phosphate, all form water-organic interfaces saturated with extractant molecules when their bulk organic concentration is larger than 10" M. 

Stoichiometric triflates [(R4TTF)+ CF3S03 ] are convenient precursors for the conversion depicted. On the addition of alkylammonium salt in acetonitrile solution, either stoichiometric (n = 0) or non-stoichiometric (n A 0) material [(RjTTF +i) X ] can be obtained. These targeted salts precipitate in a very pure state. 

The nitration of nitramine (153) with nitronium tetrafluoroborate, followed by neutralization of the resulting dinitraminic acid with ammonia, also generates ammonium dinitramide (152). Neutralization of this reaction with alkylamines, instead of ammonia, yields the corresponding alkylammonium salts of dinitramide. The nitration of ammonia with dinitrogen pentoxide (15 %) or nitronium salts like the tetrafluoroborate (25 %) yield ammonium dinitramide (152) through the initial formation of nitramine. 

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