Surfactants benzethonium chloride

Summary The polycondensation of methyltrimethoxysilane in the presence of the surfactant benzethonium chloride shows the phenomenology of a polycondensation in microemulsion. These polyorganosiloxane micronetworks can be functionalized with azo groups which are capable of grafting reaction with vinylic monomers. The structure of the resulting core shell systems depends on the polarity of the organic solvent. In DMF moleculary dissolved star-like structures were observed. 

We report here on the polycondensation of methyltrimethoxysilane [4-7] in microemulsion in the presence of the surfactant benzethonium chloride (1) [8]. 

The preparation of functionahzed silicone nanoparticles using this approach was reported in the literature [14, 15]. Several compounds of chemical structure X-Si(OCHj)j, where X=H, CH3, CH=CH3, CH2-CH=CH2, (CH )3SH, (0113)3000011=0113 were used as precursors. The homo-and co-condensation was carried out in the aqueous phase in the presence of a cationic surfactant, benzethonium chloride. The process resulted in the formation of spherical particles with the size in a range of 3-20 nm. It was shown that they can be dispersed as individual particles in common organic solvents such as tetrahydrofuran, toluene or dichlorometh-ane. However, due to their high crosslinking density (T-units... 

An excellent approach to correcting for interference from colored substances is determination of a blank value, where the colorless cationic surfactant benzethonium chloride is substituted for the cationic dye (28,29). It is common to substitute other solvents for chloroform for the extraction of the blue ion pair, with methylene chloride being most common. Greater sensitivity is said to be provided by substitution with 1,2-dichloroethane (30). Other modifications to the method have been proposed in the interest of conserving reagents (31). 

The two-phase titration is based on the reaction of anionic surfactants with cations—normally large cationic surfactants—to form an ion pair. The preferred cationic is benzethonium chloride (Hyamine 1622, 1) because of the purity of the commercially available product. On neutralization of the ionic charges, the ion pair has nonpolar character and can be extracted continuously into the organic phase, e.g., chloroform, as it is formed. The reaction is monitored by addition of a water-soluble cationic dye, dimidium bromide (2), and a water-soluble anionic dye, disulfine blue (3). The cationic dye forms an extractable... 

Benzenoids, aroma chemicals, 3 241 Benzethonium chloride cosmetic surfactant, 7 835t disinfecting agent for aquaculture in U.S., 3 213t Benzidine, 9 270, 448... 

The quaternary surfactants benzalkonium chloride (BAG) and benzethonium chloride are preferred by many manu-fecturers because of their stabihty, excellent antimicrobial properties in acid formulation, and long shelf life. They exhibit toxic effects on both the tear film and the corneal epithelium and have long been known to increase drug penetration. The toxicity of these compounds may be increased by the degree of acidity of the formulation. 

For this reason, a drug product that is to be used multiple times (multidose) must contain a preservative to prevent bacterial growth. A list of preservatives that have been used in pharmaceutical formulations is shown in Table 2. However, most of these are not usually compatible with protein formulations. Some, such as the parabens, are not active in the presence of nonionic surfactants—excipients that are typically required in protein formulations.Others may not be acceptable for a particular route of administration. Benzalkonium chloride, a commonly used preservative in topical formulations, causes ototoxicity when applied to the ear. As with buffering species, the list of preservatives available to the formulation scientist quickly narrows to just a few compounds including benzyl alcohol, phenol, w-cresol, and benzethonium chloride. A benzyl alcohol-containing formulation of epoetin alfa has been shown to be stable, even when dispensed in plastic syringes. ... 

Benzethonium chloride IM, IV, ophthalmic, otic Anionic surfactants... 

The physical properties and applications of benzethonium chloride are similar to those of other cationic surfactants such as cetrimide. 

Benzethonium chloride is incompatible with soaps and other anionic surfactants and may be precipitated from solutions greater than 2% w/v concentration by the addition of mineral acids and some salt solutions. 

Liu (2007) introduced another method called soap extraction to quantify acid number. Because the anionic surfactant can be accurately determined by potentiometric titration (see Appendix A in Liu, 2007) with benzethonium chloride (hyamine 1622), it is reasonable to use this method to find the natural soap amount. Because this potentiometric titration is for the aqueous phase, the soap should be extracted into the aqueous phase as the first step. As an anionic surfactant, the natural soap may stay in the oleic phase and form Winsor type 11 microemulsion when the electrolyte strength is high. To extract the soap into the aqueous phase, NaOH is used to keep the pH high with low electrolyte strength. Also, isopropyl alcohol is added to make the system hydrophilic so that soap will partition into the aqueous phase. 

Benzethonium chloride (Hyamine 1622, [diisobutylphenoxyethoxyethyljdimethylbenzyl-ammonium chloride, (A,A-dimethyl-A-[2-[2-[4-(l,l,3,3-tetramethylbutyl)phenoxy]-ethoxy]-ethyl]-benzenemethanammonium chloride,) [121-54-0] M 448.1, m 164-166° (sinters at 120°, monohydrate). Crystallise it from boiling acetone after filtering or from CHCls/pet ether. The precipitate is filtered off, washed with diethyl ether and dried for 24hours in a vacuum desiccator. It is a cationic antiseptic surfactant which forms crystals also from a 1 9 MeOH/Et20 mixture. It foams in water. [Beilstein 12 IV 2187.]... 

The synergisms of mixtures of anionic-cationic surfactant systems can be used to form middle-phase micro emulsions without adding short-chain alcohols [109, 110]. The surfactants studied were sodium dihexyl sulphosuccinate and benzethonium chloride. The amount of sodium chloride required for the middle-phase microemulsion decreased dramatically as an equimolar anionic-cationic surfactant mixture was approached. Under optimum middle-phase microemulsion conditions, mixed anionic-cationic surfactant systems solubilised more oil than the anionic surfactant alone. Upadhyaya et al. [109] proposed a model for the interaction of branched-tail surfactants (Fig. 8.16). According to this model the anionic-cationic pair allows oil to penetrate between surfactant tails and increases the oil solubilisation capacity of the surfactant aggregate. Detergency studies were conducted to test the capacity of these mixed surfactant systems to remove oil from... 

For example, suppose a sample of 0.5878 g of an anionic surfactant was dissolved in water and diluted to 250 ml, and that 10 ml of the solution was titrated with exactly 0.004 mol/1 benzethonium chloride. Suppose the sample had been prepared in such a way that it could be assumed to be 100% pure for all practical purposes, and that the titration volume was 16.7 ml. Then ... 

The benzethonium chloride reacts first with the anionic surfactant in the water layer, producing a colourless salt which is extracted by the chloroform. 

If necessary, confirm the completeness of the deionisation as follows. Dissolve the residue from step 8 in chloroform and dilute to volume in a volumetric flask. Test a portion of this solution for the presence of whatever ionic surfactant predominated in the sample, e.g. by adding water and acid mixed indicator and titrating with benzethonium chloride. If the nonionic matter is not completely free of ionic surfactants, repeat the analysis using twice as much resin. 

Fatty acids and acyl sarcosines may be extracted with petroleum or diethyl ether from an acidified aqueous solution if no other surfactants are present, or with petroleum ether from acidified 50% ethanol if they are. The extract is evaporated and the residue weighed. Alkylether carboxylic acids cannot be quantitatively extracted with petroleum ether. They can be extracted from aqueous solution with chloroform, but they are best determined by two-phase titration with benzethonium chloride in akaline solution (bromophenol blue method) or direct potentiometric acid-base titration. 

An elegant form of the two-phase titration method for the determination of an anionic surfactant is the following. Benzethonium chloride (Hyamin 1622, Rohm and Haas) is used as a cationic surfactant, while a mixture of diimidium bromide (cationic) and disulfin blue VN (anionic) is used as the indicator. The anionic surfactant forms a pink complex with the cationic diimidium bromide, which dissolves in the chloroform. Upon titration with Hyamin 1622, a stronger complex is formed with the anionic surfactant. Hyamin 1622 thus displaces the diimidium bromide and the organic phase is decolorized, while the aqueous phase turns red. Excess Hyamin 1622 forms a blue salt with the anionic disulfin blue VN, which then dissolves in the organic phase. 

In this section is reviewed a selection of the available evidence on this topic. Typical of the confusion that still exists is the conclusion arrived at in one paper [77] in which tetracycline, sulphanilamide, isoniazid and salicylic acid were used as test drugs and sodium lauryl sulphate, benzethonium chloride, polysorbate 80 and sucrose mono- and di-stearates as the surfactants. A perfusion technique involving the rat small intestine was employed. It was found that (i) the ionic nature of the surfactants substantially influenced the absorption (ii) the rate of absorption of tetracycline was accelerated by the presence of sodium lauryl sulphate, benzethonium chloride or sucrose esters (iii) polysorbate 80 caused a marked reduction in the absorption of salicylic acid and tetracycline ... 

This topic is dealt with in great detail by Uno and Tanaka [45-47]. Apart from the energies of repulsion and attraction due to adsorption of surfactants, adhesion may result from crystallization under the special conditions that obtain when particles are left behind after drainage of the bulk phase. Particles will be trapped by the surface tension of the liquid film (Fig. 9.18). As the particle dissolves there is supersaturation followed by deposition of the solid around the particle. According to Uno and Tanaka the solubility of the suspension particle increases at the particle-wall contact point due to the pressure exerted on the particle by the surface tension forces. Following deposition, evaporation of the continuous phase occurs as depicted in Fig. 9.18 [46]. Deposition due to cooling, to medium evaporation and to the adhesiveness of additives in the formulation can occur. The effect of polysorbate 80, benzethonium chloride, some anionic surfactants and poloxamers on the adhesion of chloramphenicol suspensions has... 

Volumetric methods are the traditional methods employed in routine controL specifically two-phase titration for anionic and cationic surfactant determination, and are characteristically highly sensitive. They are based on the reaction between an anionic surfactant and cationic surfactant (one of which is a sample surfactant and the other a titrant surfactant) in a two-phase system (chloroform-water). The endpoint is detected by a transfer-phase indicator, the most common of which is a mixture of dimidium bromide and disulfine blue although methylene blue (Epton method), which is the first indicator chronologically, is also applied. Two commonly used titrants are sodium lauryl sulfate for cationic surfactants and benzethonium chloride, currently named Hyamine 1622, for anionic surfactants. 

Sometimes, cationic surfactants have a preservative function in cosmetic formulations. For such formulations, Haruyama and Okaya (1995) proposed a method to separate cetylpyridinium, benzalkonium and benzethonium chloride. The three surfactants were simultaneously determined in lotions, creams, tonics and foams by reversed-phase and UV detection after pretreatment in the solid phase. Another technique, high-performance thin-layer chromatography (HPTLC) was used to analyse 30 preservatives in cosmetic products following a screening procedure. Two of them (cetylpyridinium and cetyltrimethylammo-nium chloride) were cationic surfactants (Imrag and Jnnker-Bnchheit, 1996). 

Volumetric methods used for hydrocarbon-type surfactants [1] are applicable to fluorinated surfactants, unless the solubility of the fluorinated surfactant imposes some limitations. Anionic fluorinated surfactants can be titrated potentiometri-cally with benzethonium chloride (Hyamine 1622), using a surfactant-selective [36] or a nitrate-selective electrode (Fig. 9.2). Cationic surfactants can be titrated... 

Active agent content of anionics is usually determined by titration with a cationic surfactant such as benzethonium chloride. Two-phase titration is suitable for assay of alkylaryl sulfonates alkyl sulfates and hydroxysulfates, alkanesulfonates, fatty alcohol ethoxysul-fates and alkyIphenolethoxysulfates and dialkyIsulfosuccinates (4,5). The results on ma-... 

Add to a 150-mL beaker a sample consisting of about 0.15 mmoles anionic surfactant in a volume of about 50 mL H2O. Titrate potentiometrically with benzethonium chloride solution at a rate of 0.5 mL/min until well past the inflection point of the curve. An automatic titrator with 5-mL buret assembly is used, equipped with a nitrate-selective electrode (HNU Systems model lSE-20-31-00, Orion model 93-07, or equivalent) and a Ag/AgCl reference electrode with ground-glass sleeve. 

A two-phase titration method for determining amine oxides in the presence of anionic surfactants calls for titration of the anionics first with benzethonium chloride at pH 9.5 using bromcresol green as indicator. A second aliquot of the sample is analyzed by adding exactly the amount of benzethonium chloride needed to complex the anionic surfactant. The amine oxide, with the ion pair of the anionic surfactant, is then extracted into chloroform at pH 9.5. The chloroform solution is mixed with water and titrated with alkyl-benzene sulfonate solution at pH 2 using methylene blue indicator (17). Another approach... 

About 200 mg surfactant is dissolved in 70 mL water in a 500-mL separatory funnel. To this are added 30 mL 20% sodium sulfate solution, 0.5 mL 2 M H2SO4, and 100 mL methylene chloride. A stoichiometric quantity (determined by a prior titration) of benzetho-nium chloride solution is added, and the separatory funnel is shaken 1 min. The methylene chloride phase is drawn off and the solvent is evaporated, leaving the benzethonium salt of the anionic. 

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