Dodecyl trimethyl ammonium bromide

Dodecyltrimethylammonium bromide n-Dodecyltrimethylammonium bromide. See Laurtrimonium bromide Dodecyl trimethyl ammonium chloride. See Laurtrimonium chloride 4-Dodecyl-N,N,N-... 

Note PEO = polyethylene oxide PVA = polyvinyl alcohol SDS = sodium dodecyl sulfate CTAB = cetyl trimethyl ammonium bromide. 

Surfactants such as cetyl trimethyl ammonium bromide (CTAB), Triton X-100 (TX-lOO) and sodium dodecyl sulphate (SDS) are the most commonly used. CTAB forms large micelles [24-26] with aggregation number 61, cmc 9.2 X 10 M, and a positive micellar Stem layer TX-lOO has aggregation number 139 with neutral OH groups on the Stern layer, and SDS forms negative micelles with cmc 8.3 x 10 M and aggregation number 131. The... 

SDS sodium dodecyl sulphate CTAB cetyl trimethyl ammonium bromide TX-lOO Triton X-100 Mb myoglobin... 

Analoge reduktive Demethylierungen lassen sich auch mit Natrium-boranat durchfuh-ren, z. B. N,N,N-Trimethyl-anilinium-jodid in Dimethyl-sulfoxid zu N,N-Dimethyl-anilin (96%) und Dodecyl-trimethyl-ammonium-bromid in Phosphorsaure-tris-[dimethylamid] (HMPT) zu 1-Dimethylamino-dodecan (65%)1. 

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) ... 

CTAB/DTAB = Cetyl/Dodecyl trimethyl ammonium bromide, DSB = Dodecyl sulfo betaine... 

FIGURE 7.11 Structure of a common anionic surfactant, sodium dodecyl sulfate (SDS), and, a cationic surfactant, dodecyl trimethyl ammonium bromide (DTAB) (from Refs. 56,57). 

CMCs of these polyfluorinated surfactants are of the order of 10 5 m.47 Plots of the observed H chemical shifts versus surfactant concentration of cetyl trimethyl ammonium chloride, cetyl pyridinium chloride, cetyl dimethyl phenyl ammonium chloride, cetyl dimethyl benzyl ammonium chloride, cetyl dimethy 1-2-phenyl ethyl ammonium chloride, and cetyl dimethyl-3-phenyl propyl ammonium chloride, are sigmoidal and were fitted to a model based on the mass action. The H chemical shift-based CMC values are in excellent agreement with those determined by the surface tension method.48 The micellization processes of dodecyl trimethyl ammonium halides (chloride and bromide) studied by calorimetric titration show different behaviors at 298 K. However, these disappear at 313 K, while the results measured by the chemical shift versus surfactant concentration do not show this difference.49 The CMC of 3-aminopropyl triethoxy silane in toluene is ca. 0.47m, measured by H and l3C chemical shifts.50 The CMC of optically active potassium A -n-dodecanoyl alaminate measured by H and l3C chemical shifts is lower (11-15 him) in D20 than that in a mixed solvent of 1,4-dioxane and D20 (19mM).-51 The H chemical shift shows that the CMC of resorcinol-type calix[4] phosphoric esters having four alkyl side-chains, [4]Ar 5P-R-n, is insensitive to the length of the side-chains, n.52 The CMC values of a family of surfactants, the sodium cyclohexyl alkanoates, with different lengths of the alkanoate side-chains, were obtained from 13C chemical-shift measurements. The results show that these amphiphiles have high CMCs (0.12-1.02 m).-53... 

Competitive displacement of spread (3-lactoglobulin from an air-water interface by (a) nonionic and (b) ionic surfactants. The collapse of the protein network is indicated by showing the change in area occupied by the protein at the interface as a function of surface pressure, (a) Data for A-Tween 20 (polyoxyethylene sorbitan monolaurate) and B-Tween 60 (polyoxyethylene sorbitan momostearate). (b) Data for A-cetyl-trimethyl-ammonium bromide (CTAB), B-lyso-phosphatidylcholinelauroyl (LPC-L), and -sodium dodecyl sulphate (SDS). 

Cationic Cetyl trimethyl ammonium bromide [CTAB]/w-alkanol w-Benzyl-w-dodecyl-w-bis(2-hydroxyethyl) ammonium chloride [BDB AC]/1 -hexanol [13-15] [16]... 

Fig. 1.4. Main types of surfactants a- nonionic on the basis of long-chain alcohol and ethylene oxide, b -anionic represented by sodium dodecyl sulphate, cationic represented by cetyl trimethyl ammonium bromide, d - betain surfactant represented by fatty acid amidopropyl dimethyl ammonio acetate, e - siloxane surfactant represented by N,N,N-trimethyl-3-(1.1.1.3.5.5.5-heptamethyl trisiloxane-3-yl) propylammonium bromide...

Figure 2.3 illustrates the results of studies on dodecyl trimethyl ammonium bromide (DTAB) at different additions of NaBr [75]. It is seen that with increasing salt concentration the shape of the curve varies and becomes displaced towards lower surfactant concentrations. The... 

Similar results were also obtained for dodecyl trimethyl ammonium bromide (C12TAB) with different additions of NaBr (cf Fig. 2.3). However, the shape of the surface tension isotherm becomes essentially different when the mean value of the ionic product c is used instead of the surfactant concentration c. The experimental isotherms of C12TAB plotted the mean... 

The Fig. 2.4 of Chapter 2 illustrates the surface tension of dodecyl trimethyl ammonium bromide (C12TAB) at different NaBr concentrations [79] as a function of the mean ionic... 

Fig. 3.70. Mixtures of sodium dodecyl sulphate (Na R ) and dodecyl trimethyl ammonium bromide (R Br ), at constant total concentration of 0.03 mmol/1, experiments according to [89], solid line - theory for adsorption of R R and desorption ofNaBr.

A simple analysis of this equation shows that the slope of the isotherm at usual values of P = 0.5 and vz/v - 0.5 should decrease drastically at the transition to the CMC. Eq. (5.144) was used later by Prokhorov and Rusanov for the evaluation of P from the surface tension of aqueous solutions of dodecyl trimethyl ammonium bromide (DTAB) [63]. The obtained value proved to be too high in comparison with the findings of independent methods. A possible reason of this discrepancy can be the assumptions used for the derivation of Eq. (5.144). Namely, the condition i = 1 can hold only at concentrations essentially exceeding the CMC. A... 

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... 

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