CETYL PYRIDINIUM

A surfactant solution is a mixture of DTAC (dodecyltrimethylammonium chloride) and CPC (cetyl pyridinium chloride) the respective CMCs of the pure surfactants are 2 X lO M and 9 x IO M (Ref. 140). Make a plot of the CMC for mixtures of these surfactants versus the mole fraction of DTAC. 

An example of the first type is the emulsion stabiliser as exemplified by sodium oleyl sulphate, cetyl pyridinium chloride and poly(ethylene oxide) derivatives. For a number of applications it is desirable that the latex be thickened before use, in which case thickening agents such as water-soluble cellulose ethers or certain alginates or methacrylates may be employed. Antifoams such as silicone oils are occasionally required. 

A buffer is used with a pH of 8.6 and then titrated with a solution of cetyl-pyridinium chloride (CPC). 

The less important positive CCAs are metal-free cationic molecules, such as the black dye nigrosine and the colorless quaternary compound cetyl pyridinium chloride.35,36... 

Avigad and Milner224 used a turbidimetric method based on the measurement of residual turbidity caused by complexing the acid polysaccharide with such quaternary ammonium detergents as cetyl-pyridinium bromide. The activity unit was expressed as the amount of enzyme bringing about a decrease of absorbance at 400 nm of 0.01/min. 

Tungsten-based catalysts including POMs show high efficiency of H202 utilization [17,18,78-100]. Ishii and coworkers [18] have reported effective H202-based epoxidation of alkenes catalyzed by H3PW12O40 combined with cetyl pyridinium chloride (CPC) as a phase-transfer agent ... 

Porte G, AppeU J, Poggi Y. Experimental investigations on the flexibility of elongated cetyl-pyridinium bromide micelles. J Phys Chem 1980 84 3105-3110. 

Figure 2. Adsorption isotherms of cetyl-pyridinium chloride on Ti02 (1 -r2) and Si02...

Commercially important surfactants based on heterocyclic structures are relatively few in number (B-80MI11510) the most important are the cationic compounds derived from imidazoline (48). Cetyl pyridinium halides (49) are used as germicides and sanitizing agents. Piperidinium (50) and morpholinium (51) compounds find application in hair conditioning formulations as antistatic agents. Substituted oxazolines (52) are a class of cationic dispersants and corrosion inhibitors. 

A nonpolar solubilizate such as hexane penetrates deeply into such a micelle, and is held in the nonpolar interior hydrocarbon environment, while a solubilizate such as an alcohol, which has both polar and nonpolar ends, usually penetrates less, with its polar end at or near the polar surface of the micelle. The vapor pressure of hexane in aqueous solution is diminished by the presence of sodium oleate m a manner analogous to that cited above for systems in nonpolar solvents. A 5% aqueous solution of potassium oleate dissolves more than twice the volume of propylene at a given pressure than does pure water. Dnnethylaminoazobenzene, a water-insoluble dye, is solubilized to the extent of 125 mg per liter by a 0.05 M aqueous solution of potassium myristate. Bile salts solubilize fatty acids, and this fact is considered important physiologically. Cetyl pyridinium chloride, a cationic salt, is also a solubilizing agent, and 100 ml of its A/10 solution solubilizes about 1 g of methyl ethyl-butyl either m aqueous solution. 

The effect of various surfactants, the cationics-eetyl trimethyl ammonium bromide (CTAB), and cetyl pyridinium chloride (CPC), the anionic-sodium lauryl sulfate (SLS), and the nonionic-polysorbate 80 (Tween 80), on the solubility and ionization constants of some sparingly soluble weak acids of pharmaceutical interest was studied (Gerakis et al., 1993). Benzoic acid (and its 3-methyl-, 3-nitro-, and 4-tert-butyl-derivatives), acetylsalicylic acid, naproxen, and iopanoic acid were chosen as model drugs. The cationics, CTAB and CPC, were found to considerably increase th< ionization constant of the weak acidS Ka ranged from-0.21 to-3.57), while the anionic, SLS, showed a negligible effect and the nonionic, Tween 80, generally decreased the ionization constants Solubility of the acids increased in aqueous micellar and in acidiLed micellar solutions. 

G. Porte and J. Appell, Growth and size distributions of cetyl pyridinium bromide micelles in high ionic strength aqueous solutions, J. Phys. Chem. 85 (1981) 2511-2519. 

One other industrial application of cationic drag reducing additives is found in oil and gas production where cetyltrimethylammonium salicylate and cetyl pyridinium salicylate have been found simultaneously to reduce drag and inhibit corrosion of tubular steel injection lines [86]. 

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... 

Polymerized Microemulsion Systems. A microemulsion of styrene and divinylbenzene with CTAB + hexanol may readily be made, and subsequently polymerized to form a polymerized microemulsion (5,6,7). This system exhibits two sites of solubilisation for photosystems such as pyrene, one in the surfactant skin layer, and the other in the polymerized styrene-divinylbenzene core. Photochemical reactions induced in the surfactant skin are very similar to those observed in micelles and are not immediately of concern to us at this stage. However, photochemical reactions induced in the rigid polymerized core are of interest, as they essentially confine reactants to a small region of space where movement is restricted as compared to a fluid non-polymerised microemulsion or a micelle. Thus, diffusion is minimised, and it may be possible to investigate reactions which occur over a distance rather than reactions which occur by diffusion. In order to eliminate reactions in the surfactant skin a microemulsion can be constructed which contains cetyl pyridinium chloride in place of CTAB. The pyrene that resides in the surfactant skin layer is immediately quenched by the pyridinium group following excitation. 

In the Pt-doped hexagonal mesophase formed from CPCI (cetyl pyridinium chloride), platinum ions are adsorbed at the surface of the surfactant cylinders. They are reduced radiolytically into a metal layer as a nanotube of around 10 nm diameter and a few hundred nm long (Fig. 3f). Extraction of all these nanostructures is achieved by dissolution of the soft template using alcohol. This possible easy extraction constitutes a marked advantage over the synthesis in hard templates, such as mesoporous silica or carbon nanotubes, the dissolution of which is more hazardous for the metal nanostructures. 

Chemicals. N,N-dimethyldodecylamine-N-oxide (DDAO) and cetyl trimethyl-ammonium bromide (CTAB) were purchased from Fluka Chemical Corp. Cetyl pyridinium chloride (CPC) and polyoxyethylene nonyl phenyl ether, with an average degree of polymerization of 10 (NP(EO)2q) were obtained from Hexacel Corp. and... 

Experimental, calculated and estimated values of Henry s constant Ki (/um) and differential heat of adsorption Qa (kJ/mol) for n-hexane adsorbed on montmorillonite modified by cetyl-pyridinium (1.1 mol/kg) at 393 K... 

A solution of a basic compound, such as Fixanol, which is essentially cetyl pyridinium bromide and cetyl trimethylammonium bromide, is added to the acid dye sample solution to precipitate the acid dye. The end point of the titration is reached when the colour of a drop of the titrated solution on filter paper is different from that of the precipitate. The drawback of this method is that the end point determination is difficult, which could lead to titration errors. A few repeated titrations may reduce the error level. 

Cation-active substances are also used to increase the wet-fastness of direct dyes. An example of such a product is Fixanol C, which is cetyl pyridinium bromide ... 

A comprehensive study of coated anion-exchange resins provides some valuable insights [20]. Of several coating materials tested, cetyl pyridinium chloride (CPI) was found to be the most satisfactory. Static coating was employed with 1-3 x I0 M CPCI in 3 % (v/v) acetonitrile-97 % water. Coating of a polyacrylate resin (Rohm Haas XAD-8) gave sharper chromatographic peaks for anions than the more hydro-phobic PS-DVB resin (Hamilton PRP-1). 

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