Cetylpyridinium bromide surfactant

The method developed by Epton [212,213] became the universally accepted method for the analysis of active matter of anionic and cationic surfactants. Epton s method, also known as the two-phase titration, is based on the titration of the anionic surfactant with cetylpyridinium bromide, a cationic surfactant, in the presence of methylene blue as indicator. A solution of the anionic surfactant is mixed with the indicator dissolved in dilute sulfuric acid, followed by further addition of chloroform, and then it is titrated with the cationic surfactant. Methylene blue forms a complex with the anionic salt that is soluble in chloroform, giving the layer a blue color. As the titration proceeds there is a slow transference of color to the water layer until the equivalence point. At the equivalence point colors of the chloroform and water layers are visually the same. On successive additions of titrant the chloroform layer lightens in shade and finally becomes colorless. 

Surfactant (cetylpyridinium bromide [CPBr]) + hexanol + salt + water... 

The objects of our experimental study were the networks of PMAA with different degree of neutralization and also networks of copolymers of AA or methacrylamide with SMA. Cetylpyridinium bromide (CPB) was employed as the surfactant. 

Chloroalkanes.1 The conversion of primary alcohols to 1-chloroalkanes with aqueous hydrochloric acid is not useful because of mediocre yields (30-60%). The rate and yield of this reaction are improved considerably by use of a surfactant such as cetyltrimethylammonium bromide or cetylpyridinium bromide. 

In addition to divalent metal cations, trivalent and tetravalent cations (i.e. ln +, Ga +, Sb +, and Sn +) were also effective as linking agents to organize [Ge4Sio]" clusters to form hexagonally ordered mesostractures. In this case, cetylpyridinium bromide was nsed as the surfactant, and formamide served as the solvent. The mesophases made with Ga + and Sb + showed intense visible photoluminescence at77K. 

Ge4Sio]" and [Fe4S4CLi] clusters was synthesized from a formamide solution containing the surfactant cetylpyridinium bromide. ... 

The ratio of the slope above to the slope below the cmc provided an estimate of P [7]. The binding constant was also used to estimate the concentration of alcohol in the bulk phase. Time resolved fluorescence quenching of dimethylnaphthalene by cetylpyridinium bromide solubilized in the micelles was used to obtain estimates of the mean aggregation number of the surfactant in the mixed micelles. 

Other cationic surfactants, cetylpyridinium bromide (CP) [27], and Zephiramine [26] have been recommended for determining Ga in a ternary system with ECR. 

Two-phase titration is usually less sensitive to interference from other foreign (nonsurfactant) species. When applied to anionic surfactant systems, two-phase titration is primarily used for the analysis of alkyl sulfates and sulfonates. Typical titrants in these applications are solutions of cetylpyridinium bromide, cetyltrimethylammonium bromide, and benzyldimethylalkyl (C12 or C14) ammonium chloride. The most accurate results are, however, obtained with p-tert-octyl-phenoxy-ethoxy-ethyl-dimethyl-benzylammonium chloride, also known under the commercial name of Hyamine 1622. The structure of Hyamine 1622 is shown in Fig. 11-32,a. 

Figure 21.39. EMF from a surfactant-specific (cetylpyridinium bromide) electrode as a function of concentration for solutions in water and ethylene glycol (cf. Figure 21.40) (reproduced from ref. (196) by permission of The Royal Society of Chemistry)...

Chloramine T (CAT) oxidation of catechol in the presence and absence of surfactant cetylpyridinium bromide is first order in CAT, and the rate increases in the presence of surfactant. Rate laws have been reported for oxidation of pyruvic acid uncatalysed in acid medium and Os(VIII)-catalysed in alkaline medium. 

Figure 4a shows a characteristic SERS spectrum from cetylpyridinium bromide (CiePyBr). This measurement was recorded at — 0.2 V vs. SCE, i.e. at a positively charged surface. With alkylpyridinium belonging to a class of cationic surfactant, the anions of the electrolyte solution may build a bridge to facilitate the adsorption of a positively charged molecule onto a positive surface. 

Typical examples of giant worm-like micelles are cationic surfactants cetylpyridinium bromide (CPyB) or cetylpyridinium cloride (CPyC) [76-79] with added NaBr, NaCl,... 

The CAT oxidation of meta-nitrophenol in AcOH has been studied both in the presence and absence of cetylpyridinium bromide (CPBr). In the absence of the surfactant the reaction is first order in CAT and zero-order in the substrate. In the presence of the surfactant the reaction is fractional order in the substrate and the increases with the increasing concentrations of CAT. The is greatly accelerated by the surfactant. ... 

Figure 4.21 shows the values for aqueous solutions of various alcohols—from methanol to butanol—which represent a continuous spectrum of values of the free energy of interaction. Very similar results were observed in the case of an aqueous solution of a classic anionic surfactant— sodium dodecyl sulfate (Figure 4.22). In this case, one is dealing with a fully reversible true equilibrium system. The same behavior was also observed for a cationic surfactant, cetylpyridinium bromide (CPB) (Figure 4.23), and to some extent, in a solution of a nonionic surfactant, polyoxyeth-ylated ether (Figure 4.24). In the latter case, however, the system is a nonequilibrium one there is a dependence of the measured pi value on time.

The early investigations on the so-called sphere-to-rodlike transitions were all concerned with the ionic surfactants SDS, cetylpyridinium bromide," tet-radecyltrimethylammonium chloride," and CTABr." The sphere-to-rodlike transition occurs in a broad range of concentrations. The concentration at which micellar transition occurs seems to be technique dependent. A micellar transition of CTABr has been reported in the concentration range from 0.05 to 0.34 mol/kg by using viscosity, Rayleigh light scattering, Br NMR, SAXS, and other tech-... 

There is now very strong evidence for a micellar phase in several aqueous cationic surfactant systems in the presence of added salt, such as cetyltri-methylanunonium bromide or chloride (CTAB or CTAC) with added KBr or sodium salicylate (NaSal), cetylpyridinium bromide (CPyBr) + KBr, ce-... 

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. 

Solutes. Toluene, although polarizable, was chosen as an apolar solute. Caffeine was chosen as a polar but nonionic solute. Four ionic solutes were tested benzyltrimethylammonium bromide (BTAB) is a cationic quaternary ammonium salt. Benzoic acid acts as an anionic solute at mobile phase pH values between 5.5 and 6.5 (the pK lies between 3.7 in CTAB solutions and 4.7 in SDS solutions)(4). Sodium paraoctylbenzene sulfonate (SOBS) (pK -0.8) and cetylpyridinium chloride (CPC) were chosen as ionic solutes having surfactant properties. Their hydrophobic "tails have the same lenghts as those of SDS and CTAB, respectively. 

Hexadecylpyridinium chloride, cetylpyridinium chloride n-Hexadecyltrimethylammonium bromide (hydroxide) or cetyltrimethylammonium bromide (hydroxide) Stoichiometric concentration of surfactant (detergent) Concentration of micellized surfactant generally [D ] = [D]-cwc... 

One factor in assessing the quality of surface waters is the amount of suspended solids or, "how muddy is it " For example the standard for many rivers and streams is 100 mg/L. If more than this occurs that segment of the stream is declared "impaired." Much of this solid material is colloidal and cannot be filtered under ordinary means. In water treatment plants, aluminum hydroxide is used to surface adsorb or simply trap the solids, and this floe then either settles out or is filtered by a gravel bed. It has been found that cationic surfactants will surface adsorb to most of the solids suspended in water, and this coating will attach to air bubbles passing th ough the system. Some surfactants proven effective are cetyldimethylethylammonium chloride, cetyldimethylbenzylammonium chloride, cetylpyridinium chloride, and ethylhexadecyldimethyl ammonium bromide. These are all antiseptics as well and are used in many mouthwashes. Only a few ppm are necessary (10 to 60) to provide clarification, and the LDjq s are in the range of 500 mg/kg. 

The kinetics of 2,4-dinitrophenyl-acetate hydrolysis catalyzed by polymers containing imidazole, carboxylic acid, oxidation groups and their complexes with surfactants, such as 1-cetylpyridinium chloride and cetylundecyldimethylammonium bromide, was determined by spectrophotometry [57]. Catalytic rate constants of the second-order-rate increase with a rise in the surfactant concentration until they reach a plateau at a polymer/surfactant ratio of 1 6. Anionic surfactant does not accelerate the polymer-catalyzed hydrolysis. The catalytic mechanism of a polymer/surfactant complex enables the penetration of the substrate into a pseudophase of a soluble complex. This leads to an increase of the ester concentration in the neighbourhood of a polymer imidazole fragment and accelerates the process. Such a pseudophase promotes the protonation of imidazole rings. 

An example of micellar oxidahon is a biomimetic system of cytochrome P450 investigated by Monh et al. [12], who foimd in the epoxidahon of styrene with NaOCl a significant influence of the type of surfactant cetylpyridinium chloride promoted the reachon more than cetyltrimethylammonium bromide. One explanahon could be a specific noncovalent interachon between catalyst, substrate and surfactant. 

In a similar study, Ebeltoft et al. mixed surfactants (sodium dodecyl sulfate, eetyltrimethylammonium bromide, or cetylpyridinium ehloride) with PSAA and studied the pressiue-area isotherms (70). All the surfaetants appeared to interact with the PSAA and in similar ways. It was concluded that PSAA monolayers are good models for emulsion-stabilizing monolayers in Norwegian crude oils. Monolayers of both PSAA and cmde oil interfacially active fractions responded similarly to the presence of ionic surfactants, indicating analogous dissolution mechanisms. 

---