CTAC, cetyltrimethylammonium chloride

In micelles of the surfactant cetyltrimethylammonium chloride (CTAC), the ratio of AA AB BB is <1 >98 <1 %. The CTAC micelles provide a cage effect, which greatly enhances the joining of the A and B radicals produced by the photolysis (Scheme 12.3). 

Preparing mixture solution A Distilled H20, NaOH and surfactant (cetyltrimethylammonium chloride, CTAC) were mixed together with stirring, then adding alumina source (if synthesis of Zr (Ti)-Si-Al material, here adding alumina source + Zr (Ti)... 

Thus, C14MV2- quenches the excited state of [Ru(bipy)3]2+ with a rate constant fcq = 8 x 10s mol-1 dm3 s-1 and this is unaffected by cetyltrimethylammonium chloride (CTAC), up to concentrations of 5 x 10-2 mol dm-3, indicating that mixed CTAC/C14MV2- micelles are not formed.139 In the absence of CTAC, kb in this system is 4x 109 mol-1 dm3 s-1, but flash photolysis showed that this drops to kb s2x 107 mol-1 dm3 s-1 in micellar solution. Thus, the more hydro-phobic radical cation, C14MV+, is solubilized by CTAC micelles, which, having a positive surface, do not allow approach of the oxidized [Ru(bipy)3]3C This then gives an efficiency of 30% for the redox reaction. This study was extended by the removal of the CTAC from solution and the introduction of a Pt catalyst protected by a positively charged polysoap.138 This work is described in Section 61.5.4.7.2. 

Another method for catalyst separation is the previously mentioned liquid/liquid technique which was studied by Gusevskaya with limonene, camphene, and myrcene in a toluene/biphasic system with Rh/TPPTS as the catalyst [47]. The addition of cationic cetyltrimethylammonium chloride (CTAC) was crucial to overcome the mass transport problems of this two-phase system. All three terpenes gave high conversions, between 71% and 96%, while the admixing of CTAC was positive in the case of myrcene and limone and negative for the reaction with camphene. 

Cetyltrimethylammonium chloride (CTAC) Cetyltrimethylammonium bromide (CTAB) Nonionic... 

Fig. 7. Molecular structure of the spin probe 4-(A, A -dimethyl-A -hexadecyl)-ammonium-2,2,6,6-tetramethyl piperidinyloxy iodide (CAT16) and the surfactant cetyltrimethylammonium chloride (CTAC).

Goldfarb et al. (65) discovered how to monitor the synthesis of MCM-41 in the liquid/solid phase by EPR spectroscopy using a nitroxide radical, 4-(A, A -dimethyl-A -hexadecyl)-ammonium-2,2,6,6-tetramethyl piperidinyloxy iodide (CAT16), as probe molecule. This nitroxide has a structure similar to that of cetyltrimethylammonium chloride (CTAC), which was used as surfactant in the synthesis of MCM-41 (Fig. 7). Thus, it was shown to be the best suited to monitor the formation process of MCM-41. Because the synthesis was performed at room temperature, commercial flat cells could be used for EPR measurements without the need for further heating. 

Parette, R., Cannon, F.S.. and Weeks, K., Removing low ppb level perchlorate, RDX, and HMX from groundwater with cetyltrimethylammonium chloride (CTAC) pre-loaded activated carbon. Water Res., 39, 4683, 2005. 

FT-EPR spectra of the ZnTPPS/DQ system in a solution of cetyltrimethylammonium chloride (CTAC), a cationic surfactant, are shown in figure B 1.16.21. As in the TXlOO solution, both donor and acceptor are... 

Figure C2.3.9. Product distribution of dissymmetrical ketone photolysis as influenced by cetyltrimethylammonium chloride (CTAC) micelles. The initial ketone, A(CO)B is photolysed to lose the carbonyl group and to produce three products, AA, AB and BB. These data are for benzyl (A) 4-methylbenzyl (B) ketone. Product AA is 1,2-diphenylethane, product BB is 1,2-ditolylethane and product AB is l-phenyl-2-tolyl-ethane. At low CTAC concentration, in the absence of micelles, a random distribution of products is obtained. In the presence of micelles, however, the AB product is heavily favoured. Adapted with permission from [57].

TABLE 8. Relative Quantum Yields (4>n) of the Blue Fluorescence of Acridine (0.12 mM) in Solutions of Spherical Micelles of Dodecyltrimethylanunonium Chloride (DTAC), Tetradecylanunonium Chloride (TTAC), and Cetyltrimethylammonium Chloride (CTAC) at pH = 12"... 

Thus, CuMV quenches the excited state of [Ruibipyfs] with a rate constant k = 8 X 10 mol dm s and this is unaffected by cetyltrimethylammonium chloride (CTAC), up to concentrations of 5 x 10 mol dm , indicating that mixed CTAC/CuMV micelles are not... 

The general features of micelles and reversed micelles (polar head buried in, with the hydrophilic tail pointing out to a low dielectric medium) can enhance the separation of photoproducts in different fashions. One of the best known examples is the effect of the surfactant cetyltrimethylammonium chloride (CTAC) on the photoreduction of by... 

Amino-4//-(l]benzopyrans are produced in good yields under aqueous conditions in a one-pot reaction of an aldehyde, malononitrile and a phenol catalysed by cetyltrimethylammonium chloride (CTAC) (Scheme 12) <01T1395>. 

The shape and size of self-assembled micellar systems depend on the conditions for a given system. Changes can be induced, e.g., by addition of cosurfactant or salt or by high surfactant concentrations. An aqueous solution of cetyltrimethylammonium chloride (CTAC) exhibits a transition from spherical micelles to elongated cylinders upon addition of chlorate anions, which is shown, for instance, by a strong increase in viscosity [25]. This system was experimentally studied by TRLQ, with results in good agreement with theory, as shown in Fig. 4. 

Anions will be separated by cationic micellar phases. Kirkbright and Mullins obtained the elution order T> N03 > Br > N02 > lOj with a 0.14 M cetyltrimethylammonium chloride (CTAC) micellar mobile phase and a C18 Spherisorb column [29]. This is the usual eluotropic order obtained with strong basic anion exclmngers. They showed that the ion retention decreased with the increase of both the ionic strength, p, and the surfactant concentration. Plots of 1/k vs. and 1/k vs. [CTAC] were linear. The first linear relationship is typical of ion-exchange mechanisms, the second plot means that the anion-micelle interaction obeys the Armstrong-Nome model for molecule-micelle partition. 

Cationic sm-factants such as tetradecyltrimethyl-ammonium bromide (TTAB), cetyltrimethylammoni-um bromide (CTAB), and cetyltrimethylammonium chloride (CTAC) have also been useful for MEKC analysis. Most cationic sm-factants have an alkyltri-methylammonium group, and their counterions are halides. The addition of cationic surfactants to the backgroimd electrolytes (BGE) caused the reversal of electroosmotic flow (EOF) owing to a positively charged capillary wall on account of the adsorption of cationic sm-factants. As a result of the reversed EOF, the polarity of the electrodes has to be reversed in order to detect the analytes. 

A low concentration of an ionic surfactant in the capillary electrolyte can also be used to modify the migration behavior of sample ions. A cationic surfactant such as cetyltrimethylammonium chloride (CTAC) is often used for anion separations, and SDS is often used when cations are to be separated. Kenata et al. [11] found that CTAC decreased the effective electrophoretic mobilities of several inorganic anions as the result of two processes ... 

Celade and De Schryver applied the same model to the fluorescence quenching in SDS micelles by neutral molecules [45,46] and in inverted micelles by halogene anions [47]. The intermicellar exchange of the counterions (iodine ions) was studied for cetyltrimethylammonium chloride (CTAC) micelles [48] and the value kg=9A X10 dm mole" s was obtained. 

Figure 12.8. Pyrene in a cetyltrimethylammonium chloride (CTAC) micelle at [CTAC] = 0.010 mol dm. A, [pyrene] = 7.5 x 10 mol dm B, 5.2 x 10 mol dm C, 1.0 x lO"" mol dm D, 2.08 x lO"" mol dm" , experimental points from transition experiment for monomer decay. Inset longer wavelength emission from the pyreme excimer obtained by steady-state experiment normalized to emission for A." ...

Bunton provided the first report on the effect of micelles formed by the cationic detergent cetyltrimethylammonium chloride (CTAC) and those formed by the anionic detergent sodium dodecyl sulfate (SDS) on the nucleophilic attack of the phosphate triester p-nitrophenyl diphenylphosphate by fluoride and hydroxide ions. In agreement with work on other reactions... 

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