Trimethyl hexadecyl ammonium bromide

Sonawane et al. [90] investigated the affect of ultrasound and nanoclay for the adsorption of phenol. Three types of nanoclay tetrabutyl ammonium chloride (TBAC), N-acetyl-N,N,N trimethyl ammonium bromide (CTAB) and hexadecyl trimethyl ammonium chloride (HDTMA), modified under sonication, were synthesized which showed healthier adsorption of phenol within only 10 min in waste water. The interlamellar spacing of all the three clay increased due to incorporation of long chain quaternary salts under cavitational effect. 

Figure 6.14 Flow curves for sodium kaolinite at pH 4. The two systems are differ only by the addition of hexadecyl trimethyl ammonium bromide (HDTAB)...

Numerical data are available from our earlier penetration work for a number of monolayer/surfactant systems. The simplest of these systems was selected for this initial analysis the penetration of cholesterol monolayers by hexadecyl-trimethyl-ammonium bromide (CTAB) J). Cholesterol monolayers at 298 K exhibit a single, highly incompressible, condensed phase with the transition to a gaseous phase occurring at a negligibly low surface pressure. CTAB does not appear to undergo surface hydrolysis (10) and the gaseous-to-expanded phase transition occurs at a low concentration (0.043 mmol kg ) and a low surface pressure (1.0 mN m l). 

Lundqvist, H., Eliasson, A.-Ch., Olofsson, G. (2002a) Binding of hexadecyl trimethyl-ammonium bromide to starch polysaccharides. Part I. Surface tension measurements. Carbohydrate Polymers, 49, 43-55. 

Figure 8.10a is an example of some data in which the effect of added salt is more than a competitive ion-binding phenomenon. The reaction involved is the decarboxylation of 6-nitrobenzisoxazole-3-carboxylate, catalyzed by hexadecyl trimethyl ammonium bromide micelles ... 

Ionescu et al.J measured the CMC of hexadecyl trimethyl ammonium bromide in water-dimethyl sulfoxide (DMSO) mixtures at 25 and 40°C ... 

Use these data to evaluate AG C for hexadecyl trimethyl ammonium bromide and to estimate (remember, only two temperatures were measured) AH%,c and AS C. Discuss the values obtained in light of infrared and NMR experiments, which indicate formation of the stoichiometric compound DMS0-2H20 at xDMSO = 0.33. 

Duynstee and Grunwald present some experimental data for Reaction (F) in the presence of hexadecyl trimethyl ammonium bromide (CTABr, C = cetyl) and sodium dodecyl sulfate (NaLS, L = lauryl). Sodium hydroxide was the source of OH" in all cases. A pseudo-first-order rate constant of 2.40 x 10-2 s-1 is observed for A CTABr. Use the following absorbance data to evaluate NaLS for this reaction ... 

The reaction of Problem 10 was studied at two different temperatures, and, from the temperature dependence of the rate constants, the authors determined AH% and ASJ, the enthalpy and entropy of activation, respectively. The following values of these parameters were obtained in pure water and in 0.01 M sodium dodecyl sulfate (NaLS) and 0.01 M hexadecyl trimethyl ammonium bromide (CTABr) ... 

As in the case of the concentration dependence of the chemical shift, the H and 13C band shapes of the surfactant resonance peaks are also concentration dependent. Analysis of H NMR band shapes for large aggregates of a cetyl trimethyl ammonium bromide-water system results in a CMC of 1.0 mM this is consistent with the value measured by other methods.57 The H NMR bands of alkyl trimethyl ammonium salicylate and hexadecyl pyridinium salicylate aqueous systems start to broaden at concentrations just above the CMC. The broadening continues up to a concentration above which the band shape is almost constant, as the concentration is further increased.-58 I3C NMR linewidth analysis of sodium octanoate in aqueous solution gives reasonable estimated CMC values.59... 

Salgaonkar, L.P. and Jayaram, R.V., Polyaniline film formation in hexadecyl trimethyl ammonium bromide admicelles on hydrous zirconia surface, J. Colloid Interf. Sci., 291. 92, 2005. 

In the case of surfactants it has been observed that sodium dodecylsulfate (SDS), Tergitol 7 [sodium 4-ethyl-1(3-ethylpentyl)octyl sulfate], and CTAB [hexadecyl(trimethyl)ammonium bromide] increase the solubility of Ss in water dramatically, provided the critical concentration for micelle formation is exceeded. For instance, 50 g 1 SDS enhance the solubility of Ss at 20 °C from 5 ng to 20 mg 1 i.e., by a factor of 4000. This enhanced solubility increases further with increasing temperature. It is believed that the surfactant molecules form micelles and that the Ss molecules dissolve in the hydro-phobic interior of these micelles in a similar fashion as in a liquid hydrocarbon solvent [16]. 

Die Hydrolyse von Trichlormethyl-benzol zu Benzoesaure wird wesentlich beschleunigt, wenn man in Ge-genwart von 0,01 M Hexadecyl-trimethyl-ammonium-bromid als Phasentransfer-Katalysator arbeitet169. 

Almost the same behaviour was found for a higher homologue of this series - octadecyl trimethyl ammonium bromide [70]. A satisfactory agreement between the molecular areas at the CMC evaluated from neutron reflection and surface tension data was obtained too. Two other homologues of this series, dodecyl and hexadecyl trimethyl ammonium bromide, were investigated in [71, 72]. Labelling of blocks of two or four atoms in the surfactant molecules allowed the authors to determine the structure of the adsorbed layer at the CMC. It was shown that the inner part of the carbon chain adjacent to the head group is oriented closer to the... 

N-laurylsarcosine and is made by mixing the CTAB (hexadecyl trimethyl ammonium bromide) and sarcosine together to form a paste before adding the rest of the solution. The EDTA is added last and the buffer is autoclaved. 

The initial important experiments in this area are due to Yoshikawa and Matsubara [26], The interface involves the upper layer containing 2-nitropropane/l-nitropropane and picric acid while the lower layer contains CTAB (hexadecyl trimethyl ammonium bromide). Oscillatory variations of pH in the aqueous phase and electric potential oscillations between organic and aqueous phases were observed. 

Given the following chemical structures, predict the probable location of each of the following compounds if solubilized in aqueous micellar solutions of (a) sodium dodecyl sulfate, (b) n-hexadecyl-trimethyl ammonium bromide, (c) polyoxyethylene(7)dodecylphenol ... 

Kawasumi etal (1997) modified the montmorillonite clay by octadecyl-amine surfactant via cation exchange process [19]. Shi and Gan (2007) used cetryl trimethyl ammonium bromide for modifying the montmorillonite [20]. Clay can also be modified using hexadecyl trimethyl bromide [21]. 

Experimentally the most accessible hydrophilic surface is the silica surface, although it is by no means simple. Except at very low concentrations, where there may be coulombic interactions between the charged surfactant and charged surface, adsorption of surfactants is generally expected to be dominated by the hydrophobic effect, which will cause the surfactant to adsorb in a bilayer or related structure. In principle, neutron reflection can identify a bilayer structure either from its overall thickness or from the surface coverage. In practice, for the two surfactants that have so far been most systematically studied by neutron reflection, the non-ionic surfactant Ci2Eg [17, 18] and the cationic surfactant hexadecyl trimethyl ammonium bromide. 

Mixed micelles of the N-acyl-L-histidine (25) and hexadecyl trimethyl ammonium bromide are effective stereoselective catalysts for the deacylation of the enantiomeric 4-nitrophenyl fV-acyl-phenylalanines (26). Increasing the chain length of the acyl group in (25) increases both the reaction rate and the enantiomer rate ratio. ... 

Figure 9 Dimensionless apparent molecular weight Mapp times the concentration c of giant surfactant micelles of hexadecyl trimethyl ammonium bromide in brine, obtained by means of light scattering measurements at a temperature of 306 K. Circles experimental data of Buhler and coworkers [50]. Line renormalization group theory for self-assembled flexible chains fitted to the data [51,52], Also indicated by the dashed lines are the predictions of scaling theory in the dilute and semidilute regimes [1,53], which agree well with results of Monte Carlo simulation [52],...

Use of surfactants is an effective way for dispersing CNTs [39]. Reports show that the outer most nanotubes in a bundle are treated more than the innermost tubes and the nanotube remains predominantly btmdled even after surfactant treatment. But mechanical methods like ultrasonication can debundle the nanotubes by steric or electrostatic repulsions [40]. On sonication the high local shear will unravel the outer carbon nanotubes in a bundle and expose other sites for additional surfactant adsorption, thus the surfactant molecules gradually exfoliate the bundle in an unzippering mechanism [41]. Some of the common surfactants used for the dispersion of carbon nanotubes are sodium dodecyl benzene sulfonate (SDBS) [42], dodecyl trimethyl ammonium bromide (DTAB) [43], hexadecyl trimethyl ammonium bromide (CTAB) [44], octylphenol ethoxylate (Triton X-100) [45] and sodium dodecyl sulfate (SDS) [46]. Covalent modification is another way to solubilize the CNTs in different solvents and to improve the interaction with the matrix in composites [47]. 

Dorrance et al have presented a series of papers reporting results of observations of both monomer and excimer fluorescence of pyrene within micelles of the cationic surfactants, decyl-, dodecyl-, tetradecyl- and hexadecyl trimethyl-ammonium bromide [116,119-121]. The concept is presented of a shell within which the planar pyrene molecules diffuse by essentially two-dimensional slippage through the hydrocarbon chains. The measurement of the temperature dependence of the rate of excimer formation in micelles containing two pyrene molecules revealed [121] that this mobility shell did not occupy the whole... 

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