Alkylammonium chain lengths

FIG. 17 Immersional wetting enthalpies as a function of alkylammonium chain lengths in (O) methanol and ( ) toluene. 

Fig. XI-14. Effect of hydrocarbon chain length on the f potential of quartz in solutions of alkylammonium acetates and in solutions of ammonium acetate. (From Ref. 183.)...

Recently, the abilities of primary to tertiary alkylammonium ions with Me, Et, and -Bu groups to transport water to NB have been studied [48]. As the result of careful consideration of the ion-pair formation, it has been shown that the hydration numbers (w ) of the ammonium ions in NB, being little affected by the alkyl chain length, are simply dependent on the class of the ammonium ion % = 1.64, 1.04, 0.66, respectively, for the primary, secondary, and tertiary ammonium ions. 

Similarly, N-alkylammonium [28] and alkylphosphonium [29] salts form lamellar phases with smectic bilayer structures. In both cases. X-ray scattering also showed the isotropic liquid not to be completely disordered and still displaying similar features to the mesophase. Buscio et al. [28] showed that in N-alkylammonium chlorides the feature was not only much broader than that observed in the mesophase but increased in width with decreasing chain length. 

Similar to the imidazolium ILs, very low solubility of the ammonium ILs was observed in alkanes. Eor example, the solubility of butyl(2-hydroxyethyl) dimethylammonium bromide, [(Ci)2C4HOC2N]Br, exhibited a simple eutectic system with immiscibility in the liquid phase in the IL mole fraction range from XjL = 0.02 to 0.70 [53] the other ammonium salt, (benzyl)dimethyl-alkylammonium nitrate, [Be(Ci)2C N] [NOJ showed very small solubility in the liquid phase in hexadecane and it was slightly better in hexane (immiscibility from XjL = 10 to 0.90) [99] for the ammonium salt with an alkane substituent only, didecyldimethylammonium nitrate, [(Cio)2(Q)2N][N03], the solubility in the liquid phase was better in hexane (immiscibility from XjL = 10 to 0.50) than in hexadecane, where the immiscibility was observed in the whole IL mole frachon [100]. In all systems with imidazolium and ammonium salts, an increase in the alkyl chain length of the alkane (solvent) resulted in a decrease of solubility. 

The dichalcogenides of group VI do not readily form intercalates with organic molecules. But n-alkylammonium compounds can be prepared by ion-exchange reactions of the hydrated sodium intercalation compounds such as Na j(H20)o g M0S2. Alkylammonium compounds prepared by this route show lattice expansions that depend on the alkyl chain length, very similar to the MX2-n-alkylamine systems described above. This raises the fundamental question whether protonated amines are the actual intercalated species in both the cases, involving reduction of the host. In fact, this constitutes the basis of the new model for the intercalation reaction in MX2 proposed by Schollhorn (1980). 

In another paper Fendler et al.59) investigated again the CMC dependence of alkylammonium propionates on the number of carbon atoms in the alkyl group of the quaternary ammonium cation (Fig. 12). The same feature as mentioned with octylammonium carboxylates is observed, i.e., the constancy of the CMC values for these alkylammonium propionates in carbon tetrachloride, while in benzene a linear plot is obtained. The latter is taken to indicate the decreased solubility of the monomers with increasing alkyl chain length in benzene. Table 471 exhibits in addition... 

Figure 4.17. Surface tension increments of aqueous solutions of alkylammonium chlorides influence of the chain length. Temperature 25°C. (Redrawn from Tamakl )...

Polymers may adsorb readily on solid surfaces. Somasundaran et al. (1964) have investigated the effect of chain length on the adsorption of alkylammonium cations and of surfactant anions on oxide surfaces. These authors consider that the adsorption is influenced by the van der Waals energy of interaction or... 

Nesper and co-workers [219, 248] synthesized nanotubules of alkylammonium intercalated VO by hydrothermal means. The vanadium alkoxide precursor was hydrolyzed in the presence of hexadecylamine and the hydrolysis product (lamellar structured composite of the surfactant and the vanadium oxide) yielded VO, nanotubes along with the intercalated amine under hydrothermal conditions (Figure 8.27(a) and (b)). The interesting feature of this vanadium oxide nanotube is the presence of vanadium in the mixed valent state, thereby rendering it redox-active. The template could not be removed by calcination as the structural stability was lost above 250 °C. Nevertheless, it was possible to partially extract the surfactant under mildly acidic conditions. These workers have later shown that the alkylamine intercalated in the intertubular space could be exchanged with other alkylamines of varying chain lengths as well as a,co-diamines [248]. The distance... 

Lan and Pinnavaia [6] showed that hybrid organic-inorganic composites exhibited mechanical properties superior to those for their separate composites. Dependence of tensile strength and modulus of epoxy nano-clay composites on the chain length of the clay-intercalated alkylammonium ions is shown in Fig. 28. The presence of the organoclay substantially increased both the tensile strength and modulus relative to the pristine polymer. The mechanical properties increased with any exfoliation in the order ... 

Figure 34-8. The effect of hydrocarbon chain length on the flotation of quartz in alkylammonium acetate solutions.

Three-component formation was observed for pyrene- and naphtha-lene-/9-CD complexes in the presence of surfactants such as n-alkyl sulfates (chain length C4-C12), n-alkylammonium chlorides (Cj-Cg), and n-al-kyltrimethylammonium bromides (CiQ-Cig) [118]. The two complexes exhibit different behavior in the presence of surfactants. With respect to the value of the two-component system, increased association constants were found for pyrene (short-chain surfactants gave higher constants than long-chain). Lower association constants were found for / -CD-naph-thalene in the presence of surfactants. By following the time course of T-T absorption of the two aromatics in the presence of nitrite, it was found that their different behaviors were due to surfactant influence on the rate constants of formation (k+) and dissociation (k ) of the inclusion compound. For naphthalene, a reduction of k+ was observed in the presence of surfactants while k was unaffected. For pyrene, short-alkyl-... 

The N2 sorption isotherm measured for MCM-41 is distinctive, being a type IV isotherm, presenting an unusually sharp capillary condensation step (Fig. 9.17). MCM-41 type mesoporous silicas are highly porous, showing BET surface areas exceeding 1000 m g and pore volumes up to 1 cm g The pore sizes usually vary between 2 and 10 nm depending on the alkylammonium surfactant chain length, the presence of... 

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