Cetyltrimethylammonium sulfate

The formyl group can be chemoselectively oxidized, in the presence of other oxidizable functionalities, in aqueous media containing an equivalent amount of surfactant. For example, 4-(methylthio)benzaldehyde is quantitatively oxidized [35] to 4-(methylthio)benzoic acid with TBHP in a basic aqueous medium in the presence of (CTA)2S04 (cetyltrimethylammonium sulfate). 

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. 

Abbreviations. aT = a-tocopherol, AC = aminocoumarin, ANS = l-anilino-8-naphthalenesulfonic acid, CTAB = cetyltrimethylammonium bromide, DPPC = dipalmitoylphosphatidylcholine, DPPH — l,l-diphenyl-2-picrylhydrazyl, DSHA = Ai-dansylhexadecylamine, GMO = glycerol monooleate, HC = hydrocoumarin, N,N -DOC = JV,JV -di(octadecyl)oxacarbocyanine, PC = phosphatidylcholine, p-CUO = pyrene caroboxaldehyde, SDES — sodium decyl sulfate, SDS — sodium dodecyl sulfate, STS = sodium tetradecyl sulfate. 

CTAB = cetyltrimethylammonium bromide DDAB = didodecyldimethylammonium bromide DEG = diethylene glycol DOE = dioctyl ether DPE = diphenyl ether DS = dodecyl sulfate EG — ethylene glycol EtOH = ethanol HAD = hexadecylamine HD = 1-hexadecene OD = 1-octadecene HDD = 1,2-hexadecanediol ... 

Shamsipur and Jalali described a simple and accurate pH metric method for the determination of two sparingly soluble (in water) antifungal agents miconazole and ketoconazole in micellar media [17]. Cetyltrimethylammonium bromide and sodium dodecyl sulfate micelles were used to solubilize these compounds. The application of this method to the analysis of pharmaceutical preparation of the related species gave satisfactory results. Simplicity and the absence of harmful organic solvents in this method make it possible to be used in the routine analyses. 

Cetyltrimethylammonium hydrogen sulfate (CTA HS04) Zwittcrionic /V-dodccyl-/V,/V -dimethyl-3 -ammonio- 1 20 100 5 93... 

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. 

The dimer of chloro(l,5-hexadiene)rhodium is an excellent catalyst for the room temperature hydrogenation of aromatic hydrocarbons at atmospheric pressure. The reaction is selective for the arene ring in the presence of ester, amide, ether and ketone functionalities (except acetophenone). The most useful phase transfer agents are tetrabutylammonium hydrogen sulfate and cetyltrimethylammonium bromide. The aqueous phase is a buffer of pH 7.6 (the constituents of the buffer are not critical). In all but one case the reaction is stereospecific giving cis products... 

The effects of micelles of cetyltrimethylammonium bromide (CTABr), tetradecyl-trimethylammonium bromide (TTABr) and sodium dodecyl sulfate (SDS) on the rates of alkaline hydrolysis of securinine (223) were studied at a constant [HO ] (0.05 m). An increase in the total concentrations of CTABr, TTABr and SDS from 0.0 to 0.2 M causes a decrease in the observed pseudo-first-order rate constants (kobs) by factors of ca 2.5, 3, and 7, respectively. The observed data are explained in terms of pseudophase and pseudophase ion-exchange (PIE) models of micelles. Cationic micelles of CTABr speed attack of hydroxide ion upon coumarin (224) twofold owing to a concentration effect. ... 

AA BAA CMC CPB CTAB DM SO IPC MVPQ PAA PDADMAB PEG PIPAA SDS SMA TEMED acrylamide methylene bisacrylamide critical micelle concentration cetylpyridinium bromide cetyltrimethylammonium bromide dimethylsulfoxide interpolymer complex methylvinylpiridine units quaternized by dimethyl sulfate poly(acrylamide) poly(diallyldimethylammonium bromide) polyethylene glycol) poly(isopropylacrylamide) sodium dodecyl sulfate sodium methacrylate tetramethylethylenediamine... 

A detailed study of the structure of the aggregates of the ionic surfactants in polyelectrolyte networks was presented in Refs. [66,68]. The dynamics of the changes in the microenvironment of the fluorescent probe, pyrene, in slightly crosslinked networks of poly(diallyldimethylammonium bromide) (PDADMAB) during diffusion of sodium dodecyl sulfate (SDS) in the gel phase has been investigated by means of fluorescence spectroscopy. In Ref. [66], an analogous investigation was reported for complexes formal by the sodium salt of PMAA with cetyltrimethylammonium bromide (CTAB). 

Therefore, inhibiting cluster formation is a possible way to avoid the problem of suppressed electron transfer. There are several methods to reduce cluster formation, e.g., by capping the surface with surfactants like lauryl-sulfate or cetyltrimethylammonium chloride, or by incorporating the fullerene derivatives into the cavity of -y-cyclodextrines [182-185,187], Transient absorption spectroscopy show that excitation to the singlet-excited state and intersystem crossing to the triplet are not effected by surfacting or incorporating fullerene derivatives... 

Normally, the CMCs of macrosurfactants have been reported in the concentration range from 10-9 to 10-4mol x L 1 [136,139] whereas common surfactants such as sodium dodecyl sulfate (SDS) or another as cetyltrimethylammonium bromide (CTAB) exhibit CMCs on the order of 1(T3 to 1 mol x L-1 [140], The CMC might be absent for macrosurfactants [141],... 

Micellar effects were found to be variable and dependent on the type of micelle employed. Cationic micelles, such as cetyltrimethylammonium bromide, inhibited hydration. Anionic micelles formed from sodium lauryl sulfate (NaLS) produced a small amount of catalysis at low concentration, exp actually passing through a maximum at [NaLS] < the critical micelle concentration (cmc). On the other hand, micelles formed from monopotassium -dodecyl phosphate in unbuffered water give impressive catalysis relative to water itself. Detailed discussion of these effects is given in Reference 80. 

The surfactant-aided Lewis acid catalysis was first demonstrated in the model reaction shown in Table 13.1 [22]. While the reaction proceeded sluggishly in the presence of 10 mol% scandimn triflate (ScfOTOs) in water, a remarkable enhancement of the reactivity was observed when the reaction was carried out in the presence of 10 mol% Sc(OTf)3 in an aqueous solution of sodium dodecyl sulfate (SDS, 20 mol%, 35 mM), and the corresponding aldol adduct was obtained in high yield. It was found that the type of surfactant influenced the yield, and that Triton X-100, a non-ionic surfactant, was also effective in the aldol reaction (but required longer reaction time), while only a trace amount of the adduct was detected when using a representative cationic surfactant, cetyltrimethylammonium bromide (CTAB). The effectiveness of the anionic surfactant is attributed to high local concentration of scandium cation on the surfaces of dispersed organic phases, which are surroimded by the surfactant molecules. 

The complex [ RhCl(l,5-COD) 2] and a phase transfer catalyst (cetyltrimethylammonium bromide or tetrabutylammonium hydrogen sulfate) also reduce aromatic hydrocarbons under hydrogen. ... 

Aggregation to form micelles usually occurs over a very narrow concentration range as the total concentration is raised, and is associated with an abrupt change in the turbidity of the solution. The concentration of the surfactant that corresponds to the point at which micelles first form in the solution (critical micelle concentration, cmc) usually decreases with increase in the hydrocarbon chain length. The cmc for sodium dodecyl sulfate (SDS), a 12-carbon anionic surfactant, is 8.1 mM and the cmc for hexadecyltrimethylammonium bromide [cetyltrimethylammonium bromide (CTAB)], a 16-carbon cationic surfactant, is 0.92 mM. In general, the number of surfactant monomers per micelle, i.e., its aggregation number, can vary from less than 10 to more than 100. 

Ionic lipids Lauryl sulfate, dodecyl-2-pyrrolidone, Wdodecyl azacycloheptan-2-one (Azone), ACdodecyl-A, A -dimethyl betaine, calcium dodecylbenzene sulfonate, dioctyl sodium sulfosuccinate, dodecyl A, ACdimethylamino (acetate or proprionate), and cetyltrimethylammonium bromide... 

---