Dodecyltrimethylammonium bromid

Dodecyltrimethylammonium bromide [1119-94-4] M 308.4, m 246°(dec). Purified by repeated crystn from acetone. Washed with diethyl ether and dried in a vacuum oven at 60° [Dearden and Wooley J Phys Chem 91 2404 1987]. 

Hong et al. applied capillary EKC with dodecyltrimethylammonium-bromide/sodium dodecylsulfate (12.7/21.1 mM) vesicles to the separation of alkylphenones (Fig. 8A) and obtained better resolution than with sodium dodecylsulfate micelles (59). The logarithms of the retention factors for 20 neutral compounds of similar structures showed an excellent linear correlation with log Poct (R2 = 0.98). Similarly, Razak et al. (60) showed that the log capacity factors for interaction between neutral and positively charged analytes and cetyltrimethylammoniumbromide/sodium octylsulfate vesicles correlated linearly with the log Poa values. 

Contrary to hydrotropes, micelle-forming surfactants spontaneously self-aggregate cooperatively above the critical micelle concentration (cmc) even in the absence of solubilizate. Typical examples of micelle-forming surfactants include sodium dode-cylsulfate (SDS), dodecyltrimethylammonium bromide (DTAB), cetyltrimethyl-ammonium bromide (CTAB), and heptaoxyethylene dodecyl ether (C12E7) (Scheme 2). 

CZE-ELD, with a An microelectrode at —0.6 V vs. SCSE and a Pt wire as auxiliary electrode, using sodium borate buffer and dodecyltrimethylammonium bromide for dynamic coating of the capillary internal surface, can be applied for separation and determination of hydroperoxides in ultra-trace amounts. Thus, various hydroperoxides derived from linoleic acid undergo total dissociation to carboxylates in borate buffer however, due to their similar molecular masses, in order to resolve the ELD signals, it is necessary to add /3 -cyclodextrin (83) to form complexes with the analytes and reduce their mobility, in accordance with the value of the complexation equilibrium constants . 

DOC (dissolved organic carbon), 606, 607-8 Dodecyltrimethylammonium bromide, 744 Domino reactions, thiyl and selenyl radicals, 221-3, 224, 225, 226-7 DOPA (3,4-dihydroxyphenylalanine), 614, 615... 

Our group [124] has used pyrene and pyrene labeled poly(acrylic acid) as a fluorescent probe to investigate the interaction between poly(acrylic acid) (PAA) and dodecyltrimethylammonium bromide (DTAB) in water. We have measured the Is /1 ratio of pyrene as a function of DTAB in the presence of 1 g/L PAA. A sharp decrease in polarity is found well below the CMC of DTAB (1.3 X 10 M, Fig. 17). The onset of this polymer-induced association is referred to as the critical aggregation concentration. The CAC has been measured at various pH and NaCl levels (Fig. 18). It was observed that the... 

Fig. 23 Schematic representation of the formation of polymer surfactant complexes for the pyrene-labeled (polyacrylic acid)-dodecyltrimethylammonium bromide system for high (high pH) and low (low pH) degrees of ionization...

Actual transfer distance along the primary DNA ds Interduplex center-to-center separation Spermine tetrahydrochloride Dodecyltrimethylammonium bromide Octadecyltrimethylammonium bromide Poly-L-lysine hydrobromide Polyethylenimine hydrochloride Ionization energy... 

Dodecyltrimethylammonium bromide [1119-94-4] M 308.4. Purified by repeated crystn from... 

C, MoS-L-14C, MoS-L-12C respectively) with cetyltrimethylammonium bromide (C H42NBr), myristyltrimethylammonium bromide (C17H3,NBr) and dodecyltrimethylammonium bromide (C 5H34NBr) as the templates (designated QH NBr in general). 

A preliminary report (10) and a more detailed one (7) of the techniques employed are published elsewhere. Four cationic soaps are used as follows dodecyltrimethylammonium bromide (Ci2TABr,I) hexadecyl-trimethylammonium bromide H (Ci6TABr,II), hexadecylpyridinium chloride (Ci6PyCl,III), and hexadecyldimethylethylolammonium bromide (CioCholBr,IV). The last compound is related to choline bromide,... 

The relative adsorbability of sulfate against bromide ions of aqueous solution of dodecyltrimethylammonium bromide (0.0150 mole/liter) containing a small amount of sulfate ions (0.0000594 equiv./liter of Na235S04) was summarized in Table II. 

Table II. Relative Adsorbability of 33S042 Against Bromide at the Air-Solution Interface of an Aqueous Solution of Dodecyltrimethylammonium Bromide (0.0150 mole/liter) at 20°C.

S. Ozeki and S. Ikeda, The sphere-rod transition of micelles and the 2-step micellization of dodecyltrimethylammonium bromide in aqueous NaBr solutions, J. Colloid Interface Sci. 87 (1982) 424-435. 

Materials. Sodium dodecylsulfate (SDS) and fully deuterated sodium dodecylsulfate (SDS-d ) were obtained from Sigma and Cambridge Isotope Laboratories respectively, and used as received. The cationic surfactants, dodecyltrimethylammonium chloride (DTAC), dodecyltrimethylammonium bromide (DTAB), and didodecyldimethylammonium bromide (DDAB) were purchased from Eastman Kodak, and purified by repeated recrystallization from an ethanol/acetone solvent pair. Even so, a small amount of surface active impurity was observed in surface tension plots for DTAC. The tetradecyldimethylamine oxide (C14AO) was a commercial sample (Ammonyx MO) obtained from Stepan (Control No. 533-30027). This sample is primarily C14AO, but also contains other chain length components. Sodium chloride (NaCl) was obtained from EM Science and used as received. Water was purified by a three stage Bamstead water purification system. 

The effect of micellar solutions of sodium dodecanoate (laurate) and n-dodecyltrimethylammonium bromide on the rate of alkaline hydrolysis of p-nitrophenyl acetate, mono-p-nitrophenyl dodecanedioate, and p-nitrophenyl octanoate has been investigated by Menger and Portnoy... 

Fig. 6. Plots of for the hydrolysis of p-nitrophenyl acetate (A), mono-p-nltrophenyl dodecanedioate (B), and p-nitrophenyl ootanoate (C) at pH 9-59, I = 0-1 and 50° vs. sodium dodecanoate (laurate) concentration (on the left) and at pH 10-49, I = 0-2 and 50° vs. n-dodecyltrimethylammonium bromide (LTAB) concentration (on the right). Values of k,/, for the reaction of A -with sodium laurate have been divided by 2-0 to bring the curve on scale (Menger and Portnoy, 1967).

The effects of dodecyltrimethylammonium bromide and chloride, tetradecyltrimethylammonium bromide, CTAB, and NaLS on the dissociation constants of 20a and 20c were investigated by Mukerjee and Banerjee (1964), and the differences between the bulk and the micellar surface pK s of the indicators were interpreted in terms of the electrical potential difference and changes in the pX. Thus, the higher pK at the surface of the cationic micelles as compared to that in the bulk solution can be attributed to a lower effective dielectric constant at the micelle surface. 

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