Cetyltrimethylammonium surfactant

Frasch, J. et al., In situ investigations on cetyltrimethylammonium surfactant/silicate systems precursors of organized mesoporous MCM-41-type siliceous materials, Langmuir, 16, 9049, 2000. 

It was found that the effect of solvents and various surfactants Triton X-100, Twin-80, Brij-35 sodium laurylsulfate, sodium cetylsulfate, cetylpyridinium chloride, cetyltrimethylammonium bromide on the luminescence intensity is insignificant. 

Kuczynski and Thorns also studied the formation of MV in CdS solution using a cationic surfactant, cetyltrimethylammonium bromide, as a stabiliasr. In the presence of ethylenediaminetetraacetate (EOTA), the MV " yield was greatly increased. EDTA and MV " form a complex with a resultant negative charge, which is electrostatically bound to the cationic CdS surface. The MV " formed is repelled by the positive charge of the cationic stabilizer, a fact which makes the charge separation efficient. 

Recently, the newly developed time-resolved quasielastic laser scattering (QELS) has been applied to follow the changes in the surface tension of the nonpolarized water nitrobenzene interface upon the injection of cetyltrimethylammonium bromide [34] and sodium dodecyl sulfate [35] around or beyond their critical micelle concentrations. As a matter of fact, the method is based on the determination of the frequency of the thermally excited capillary waves at liquid-liquid interfaces. Since the capillary wave frequency is a function of the surface tension, and the change in the surface tension reflects the ion surface concentration, the QELS method allows us to observe the dynamic changes of the ITIES, such as the formation of monolayers of various surfactants [34]. 

It follows from the above that the mechanism for electrical potential oscillation across the octanol membrane in the presence of SDS would most likely be as follows dodecyl sulfate ions diffuse into the octanol phase (State I). Ethanol in phase w2 must be available for the transfer energy of DS ions from phase w2 to phase o to decrease and thus, facilitates the transfer of DS ions across this interface. DS ions reach interface o/wl (State II) and are adsorbed on it. When surfactant concentration at the interface reaches a critical value, a surfactant layer is formed at the interface (State III), whereupon, potential at interface o/wl suddenly shifts to more negative values, corresponding to the lower potential of oscillation. With change in interfacial tension of the interface, the transfer and adsorption of surfactant ions is facilitated, with consequent fluctuation in interface o/ wl and convection of phases o and wl (State IV). Surfactant concentration at this interface consequently decreased. Potential at interface o/wl thus takes on more positive values, corresponding to the upper potential of oscillation. Potential oscillation is induced by the repetitive formation and destruction of the DS ion layer adsorbed on interface o/wl (States III and IV). This mechanism should also be applicable to oscillation with CTAB. Potential oscillation across the octanol membrane with CTAB is induced by the repetitive formation and destruction of the cetyltrimethylammonium ion layer adsorbed on interface o/wl. Potential oscillation is induced at interface o/wl and thus drugs were previously added to phase wl so as to cause changes in oscillation mode in the present study. 

Using cetyltrimethylammonium bromide (CTAB) as a surfactant, Krafft et al. have developed an efficient stoichiometric inter- and... 

The Henry (nitroaldol) reaction was reported under very mild reaction conditions, in aqueous media using a stoichiometric amount of a nitroalkane and an aldehyde, in NaOH 0.025 M and in the presence of cetyltrimethylammonium chloride (CTAC1) as cationic surfactant (Eq. 8.94) 240 Good to excellent yields of (i-nitroalkanol are obtained. Under these conditions several functionalities are preserved, and side-reactions such as retro-aldol reaction or dehydration of 2-nitroalcohols are avoided. 

Compared to inorganic materials, organic materials such as polymers, surfactant molecules and micelles also act as a capping material or soft template. Figure 5.15 shows TEM images of gold nanorods and nanoparticles synthesized by sonochemical reduction of Au(I) in the presence of cetyltrimethylammonium bromide,... 

The nitro-aldol reaction can also be carried out in water using NaOH in the presence of cetyltrimethylammonium chloride (CTAC1) as a cationic surfactant. CTAC1 (5 mmol) is added to a mixture of nitroalkane (50 mmol) and aldehyde (50 mmol) in NaOH 0.025 M (150 mL) at room temperature. The mixture is stirred for 2-3 h and worked up to give the product in 70-90% yield. Compared with the classical methods, this procedure has economical and environmental advantages (Eq. 3.16).27... 

In recent years, there has been increased recognition that water is an attractive medium for organic reactions from the environmental point of view. The Michael addition of various nitroalkanes to conjugated enones can be performed in NaOH (0.025 M) and in the presence of cetyltrimethylammonium chloride (CTAC1) as cationic surfactant in the absence of organic solvents (Eq. 4.109).146 The Michael addition of nitromethane to methyl acrylate is carried out in water using NaOH as a base to give the mono adduct (Table 4.2).147... 

Recently, a detailed study was reported for a molecularly ordered layered silicate surfactant mesophase [125, 126]. A subtle change in the surfactant which is used for the synthesis of such mesophases appears to induce dramatic modifications in the silica ordering. When cetyltrimethylammonium (C16NMe3+) cations are employed, then only two 29Si NMR resonances at —102 ppm (Q3) and... 

Howard [27] determined dissolved aluminium in seawater by the micelle-enhanced fluorescence of its lumogallion complex. Several surfactants (to enhance fluorescence and minimise interferences), used for the determination of aluminium at very low concentrations (below 0.5 pg/1) in seawaters, were compared. The surfactants tested in preliminary studies were anionic (sodium lauryl sulfate), non-ionic (Triton X-100, Nonidet P42, NOPCO, and Tergital XD), and cationic (cetyltrimethylammonium bromide). Based on the degree of fluorescence enhancement and ease of use, Triton X-100 was selected for further study. Sample solutions (25 ml) in polyethylene bottles were mixed with acetate buffer (pH 4.7, 2 ml) lumogallion solution (0.02%, 0.3 ml) and 1,10-phenanthroline (1.0 ml to mask interferences from iron). Samples were heated to 80 °C for 1.5 h, cooled, and shaken with neat surfactant (0.15 ml) before fluorescence measurements were made. This procedure had a detection limit at the 0.02 pg/1 level. The method was independent of salinity and could therefore be used for both freshwater and seawater samples. 

It is seen from Table 11.1 that surfactant cetyltrimethylammonium bromide (CTAB, RN MexBr ) exerts a positive catalytic effect on ethylbenzene autoxidation. The kinetic study of this phenomenon [21,27] showed that the acceleration was caused by the additional reaction of hydroperoxide with the bromide ion of CTAB to form free radicals [30],... 

Equation (1) is generally used to estimate the rate constant, kin the micellar pseudophase, but for inhibited bimolecular reactions it provides an indirect method for estimation of otherwise inaccessible rate constants in water. Oxidation of a ferrocene to the corresponding ferricinium ion by Fe3 + is speeded by anionic micelles of SDS and inhibited by cationic micelles of cetyltrimethylammonium bromide or nitrate (Bunton and Cerichelli, 1980). The variation of the rate constants with [surfactant] fits the quantitative treatment described on p. 225. Oxidation of ferrocene by ferricyanide ion in water is too fast to be easily followed kinetically, but the reaction is strongly inhibited by anionic micelles of SDS which bind ferrocene, but exclude ferricyanide ion. Thus reaction occurs essentially quantitatively in the aqueous pseudophase, and the overall rate depends upon the rate constant in water and the distribution of ferrocene between water and the micelles. It is easy therefore to calculate the rate constant in water from this micellar inhibition. 

See also Cetyltrimethylammonium bromide (CTAB) surface area antimicrobial used in cosmetics, 7 847 cosmetic surfactant, 7 834t Cetus, 11 12 Cetyl alcohol, 22 756 properties of commercial, 2 llt Cetyl bromide, physical properties of, 4 350t... 

Figure 4.23 Synthesis space diagram for a ternary system composed of tetraethylorthosilicate (TEOS), cetyltrimethylammonium bromide (CTAB), and sodium hydroxide (H, hexagonal phase [MCM-41] C, cubic phase [MCM-48] L, lamellar phase [MCM-50] H20/Si02 = 100, reaction temperature 100°C, reaction time 10 days). (Reprinted from Science, Vol. 267, A. Firouzi, D. Kumar, L.M. Bull, T. Besier, R Sieger, Q. Huo, S.A. Walker, J.A. Zasadzinski, C. Glinka, J. Nicol, D.l. Margolese, G.D. Stucky, B.F. Chmelka, Cooperative Organization of Inorganic-Surfactant and Biomimetic Assemblies, pp. 1138-1143. Copyright 1995. With permission of AAAS.)...

Figure 12.1 Schematic representation of a micelle (bottom) by aggregation of cetyltrimethylammonium bromide (C H NfCHUiBr-) surfactant molecules (top)...

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). 

Other commonly used surfactants are cetyltrimethylammonium bromide (CTAB), Brij, Tween, Triton X and Siloxane polyether copolymer (PSPEO) [53]. 

A wide choice of cationic surfactants such as CTAB (cetyltrimethylammonium bromide), CTAH (cetyltrimethylammonium hydroxide), TTAB (tetradecyltrimethylammonium bromide), TTAOH (tetradecyltrimethylammonium hydroxide), MTAB (myristyltrimethylammo-nium bromide), OFM (OFM Anion-BT, Waters, Milford, MA, USA), HDB (hexadimethrine bromide), and many others may be used to reverse the EOF. CTAH and TTAOH should be preferred to CTAB and TTAB to avoid interference from bromate contamination. The capillary coating is performed just by rinsing with the BGE containing this flow modifier or even with an additional rinse step with a solution containing this flow modifier. 

An interesting sonochemical synthesis of elongated copper nanoparticles (approx. 50 X 500 nm) has been described [164]. The principle of the method is the use of an organised medium of aqueous cetyltrimethylammonium p-toluenesulphonate as the supporting fluid for sonication. The resulting nanoparticles are produced from the sonication of copper hydrazine carboxylate in the interconnected threadlike micelles which act as a template. The nanoparticles are coated with a layer of the surfactant. In the absence of the detergent the particles were spherical (ca. 50 nm). 

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