Hexadecyltrimethylammonium bromide CTAB

DNA from those sources rich in polysaccharides can be purified by the addition of CTAB (hexadecyltrimethylammonium bromide) before chloroform isoamyl alcohol extraction [6], After adjusting NaCl concentration to 0.7 M with 5 M NaCl in a DNA solution solution (ca. 0.05 mg/mL in TE), CTAB solution (10% CTAB in 0.7 M NaCl) is added so that the final concentration of CTAB is about 1%. The samples are incubated at 65°C for 10 minutes. It is important to keep the salt at a concentration of greater than 0.5 M so that the DNA does not precipitate as a CTAB-DNA complex. After the addition of an equal volume of chloroform-isoamyl alcohol (24 1 by volume) and gentle but complete mixing, the phases are separated by centrifugation for 10 minutes at 2000 x g. The interphase will appear as a white precipitate of CTAB-polysaccharides/protein complex. The aqueous phase containing DNA is transferred with a wide-bore pipette to a tube, and the CTAB chloroform-isoamyl alcohol extraction can be repeated until no cellular material is visible at the interphase. The DNA from the aqueous phase is precipitated with ethanol as described earlier, and any residual CTAB is washed with 70% ethanol washes. 

Malatesta 43 investigated the photochromism and thermochromism of spirooxazines in cationic (CTAB, hexadecyltrimethylammonium bromide) and nonionic (TX-100) micellar solutions, and in sodium bis-2-ethylhexylsulfosuccinate (AOT) toluene-water inverted micelles. The thermo- and photocolorability increased in TX-100 and CTAB micelles and decreased in inverted micelles. 

Average value obtained using 2,6-diphenyl-4-(2,4,6-triphenyl-l-pyridinio)phenoxide, 1-hexadecyl-4-[(oxocyclohexadienylidene)ethylidene]-l,4-dihydropyridine, l-hexadecyl-5-hydroxyquinoline and l-hexadecyl-6-hydroxyquinoline, average deviation <9 % calculated from [47d]. Abbreviations SDS = sodium dodecyl sulfate DBS = dodecyl benzenesulfonate CTAC = hexadecyltri-methylammonium chloride CTAB = hexadecyltrimethylammonium bromide DTAC = dodecyl-trimethylammonium chloride DTAB = dodecyltrimethylammonium bromide DHP = dihexadecyl phosphate DDDAB = didodecyldimethylammonium bromide DMPC = dimyristoylphosphati-dylcholine DPPC = dipalmitoylphosphatidylcholine POPC = l-palmitoyl-2-oleoylphosphati-dylcholine PCA = phosphatidic acid. 

Abbreviations CTAB = hexadecyltrimethylammonium bromide SHDTE = sodium hexadecyl-trioxyethylene sulfate SDS = sodium dodecyl sulfate DTAB = dodecyltrimethylammonium bromide TTAB = tetradecyltrimethylammonium bromide bpy = 2,2 -bipyridyl MV- = N,N -dimethyl-4,4 -bipyridinium Rh = octadecylrhodamine DMA = A, .V-dimethylaniline. 

Cetraria islandica extract Cetraria islandicus. See Iceland moss (Cetraria islandicus) extract Cetrimide BP, Cetrimide BP, Cetrimide Cetrimide. SeeCetrimonium bromide Cetrimonium bromide CAS 57-09-0 EINECS/ELINCS 200-311-3 Synonyms CETAB Cetrimide Cetyltrimethylammonium bromide CTAB Hexadecyltrimethylammonium bromide HTAB Trimethylcetylammonium bromide N,N,N-Trimethyl-1-hexadecanaminium... 

FIGURE 3.1 Some examples of common surfactant molecules, from top anionic surfactant SDS (sodium dodecyl sulfate, also commonly known as sodium lauryl sulfate) cationic surfactants CTAB (hexadecyltrimethylammonium bromide), DDAB (didecyidimethylammonium bromide) commercial nonionic detergent Triton X-100 and zwitterionic lipid DOPC (1,2-dioleoyl-sn-glycero-3-phosphocholine). 

Heterocarpus luciferase, 344, 363 Heterophotus, 338 Heterorbabdus, 336 Heteroteuthis, 334 Hexadecanal, 32, 35, 36 Hexadecyltrimethylammonium bromide, 61, 164, 277-299 See CTAB... 

Nanoparticles of the semicondnctor titanium dioxide have also been spread as mono-layers [164]. Nanoparticles of TiOi were formed by the arrested hydrolysis of titanium iso-propoxide. A very small amount of water was mixed with a chloroform/isopropanol solution of titanium isopropoxide with the surfactant hexadecyltrimethylammonium bromide (CTAB) and a catalyst. The particles produced were 1.8-2.2 nm in diameter. The stabilized particles were spread as monolayers. Successive cycles of II-A isotherms exhibited smaller areas for the initial pressnre rise, attributed to dissolution of excess surfactant into the subphase. And BAM observation showed the solid state of the films at 50 mN m was featureless and bright collapse then appeared as a series of stripes across the image. The area per particle determined from the isotherms decreased when sols were subjected to a heat treatment prior to spreading. This effect was believed to arise from a modification to the particle surface that made surfactant adsorption less favorable. 

The geometry and surface chemistry of the dendrimer assemblies can be varied through the addition of surfactants. These dendrimer/surfactant aggregates can be tuned to template the formation of the different phases of calcium carbonate [40]. In combination with hexadecyltrimethylammonium bromide (CTAB), small spherical aggregates were formed that induce the formation of vaterite. Over a period of five days, the vaterite was transformed into calcite. The use of the negatively charged surfactant, sodium dodecylsulfonate (SDS), result-... 

Acid detergent solution - add 100 g cetyl trimethylammonium bromide (CTAB), also called hexadecyltrimethylammonium bromide, technical grade, to 2.5 I of 1 M sulphuric acid, stir to dissolve and make up to 5 I... 

It is noteworthy that the indenyl complex RuCl(ri -C9H7)(PPh3)2l4 provides an efficient catalyst precursor for the anti-Markovnikov hydration of terminal alkynes in aqueous media, especially in micellar solutions with either anionic (sodium dode-cylsulfate (SDS)) or cationic (hexadecyltrimethylammonium bromide (CTAB)) surfactants [38]. This system can be applied to the hydration of propargylic alcohols to selectively produce P-hydroxyaldehydes, whereas RuCl(Cp)(PMe3)2 gives a,P-unsat-urated aldehydes (the Meyer Schuster rearrangement products)(Scheme 10.8) [39]. 

Hexadecyltrimethylammonium bromide (CTAB) [57-09-0] M 364.4. Recrystd once from acetone,... 

Hexadecyltrimethylammonium bromide (CTAB) [57-09-0] M 364.4. Recrystd once from acetone, acetone/water or acetone and <5% MeOH and dried under vacuum at 60°. Also crystd from absolute EtOH. [Dearden and Wooley JPC 91 2404 1987]... 

Fig. 2.20. Phase diagram (at 25 °C) from the work by Ekwall and co-workers (cf. Refs.8 86)) for the three-component system hexadecyltrimethylammonium bromide (CTAB) - hexanol -water. Li denotes a region with water-rich solutions L2 a region with hexanol-rich solutions D and E are lamellar and hexagonal liquid crystalline phases, respectively. In the figure are also schematically indicated the structures of normal (Lj region) and reversed (L2) micelles as well as of the liquid crystalline phases. (From Ref.9Sb...

For hexadecyltrimethylammonium bromide (CTAB) there is evidence of several types (X-ray diffraction83, conductance anisotropy192, flow birefringence193, ... 

Aqueous solution of SWNTs was suspended with different types of surfactants a) anionic (SDS) (CH3(CH2)ii(S04) Na+), b) cationic (hexadecyltrimethylammonium bromide (CTAB) (CH3(CH2)i5N+(CH3)3Br) and c) and non-ionic (Tween-80) H(Et-0)n0(C4H602CH0HCH20 CO(Ci8H23). Surfactants SDS and CTAB were purchased from Serva , Tween-80 from Shuchard (Germany). 0.05 mg/mL nanotube dispersion with surfactant was mixed and then the suspension was sonicated for 40 minutes. A concentration of surfactants in water solution was 1%. Water was prepared by distillation and then passed through Multi-Q system. The deionized water has resistance 18 MO. 

The hydrolysis at 25 °C of p-nitrophcnyl picolinate (71) catalysed by the Cu(II) complex of 4-chloro-2,6-di(iV-hydroxyethylaminomethyl)phenol (72 R = CH2NH CH2CH2OH) was studied kinetically at different pH in the presence of three surfactants hexadecyltrimethylammonium bromide, sodium lauroylsarcosinate, and polyoxyethylene (23) lauryl ether.69 The Cu(II) complexes of two iV-alkyl-3,5-di(hydroxy-methyl)-1,2,4-triazoles (73 R = CioH2i, Ci2H2s) were better than the Ni(II) complexes as catalysts for the hydrolysis of p-nitrophcnyl picolinate (71) in CTAB micelles.70... 

Preheat 25 mL of hexadecyltrimethylammonium bromide (CTAB) isolation buffer... 

Figure 1. Observed rate constants vs. chain length for the basic hydrolysis of RCOsCo(NHs)s in an aqueous hexadecyltrimethylammonium bromide (CTAB) solution. Key O, this work.

Figure 2. Orientation of the RCOtCo(NH,)s complex at the interface of a microemulsion containing hexadecyltrimethylammonium bromide (CTAB).

Relatively small retardations of the rate of the base catalyzed hydrolysis of methyl-1-naphthoate by sodium dodecylsulfate (NaLS) and hexadecyltrimethylammonium bromide (CTAB) in 50 wt percent dioxane-water have been observed. These effects were attributed to micelle formation in this solvent system since plots of In where 2 and are the second order rate constants in the presence and absence of the organic salts, vs. the concentration of the salts were non-linear... 

The reactions of a phosphate triester, p-nitrophenyl diphenyl phosphate with hydroxide and fluoride ions has been demonstrated to be catalyzed strongly by cationic surfactants and inhibited by NaLS and a non-ionic surfactant (Bunton and Robinson, 1969a Bunton et al., 1969, 1970). Hexadecyltrimethylammonium bromide (CTAB) increased the second-order rate constant for the reaction ofp-nitrophenyl diphenyl phosphate with hydroxide ion by a maximum factor of approximately 11 and that with fluoride ion by a maximum factor of approximately 33 at CTAB concentrations of 3 x 10 m and 2 x 10 m respectively. At higher detergent concentrations the catalysis became progressively less pronounced (Fig. 11). This behavior does not fit equation (10) (Bunton and Robinson, 1969a). However, a number of other micelle-catalyzed reactions between anions and neutral molecules have been found to... 

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. 

Most of the work concerned with micellar catalysis of nucleophilic substitution refers to reactions of the Aac2 and SN2 types and will not be reviewed here. To date only a few systems have been examined in which a micellar medium affects the partitioning of solvolytic reactions between unimolecular and bimolecular mechanisms. The effects of cationic (hexadecyltrimethylammonium bromide = CTAB) and anionic (sodium lauryl sulfate = NaLS) micelles on competitive SN1 and SN2 reactions of a-phenylallyl butanoate 193) have been investigated189. The rate of formation of the phenylallyl cation 194) is retarded by both surfactants probably as a consequence of the decreased polarity of the micellar pseudo phase. The bimolec-... 

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