Polyoxyethylene ethers

Masparov [53] and coworkers measured with lauryl alcohol ethoxylated with 6 mol EO a better detergency and wetting effect than with the corresponding polyoxyethylene ether carboxylic acid. 

Clothier, Jr., J. G. and Tomellini, S. A., Chiral separation of veraprimil and related componds using micellar electrokinetic capillary chromatography with mixed micells of bile salt and polyoxyethylene ethers,. Chromatogr. A, 712, 179,1996. 

ID and 2D 13C NMR were carried out in a series of novel nematogens by Bayle and co-workers to study the effects on the conformation and order due to the addition of lateral and/or terminal substituents.249 251 For example, lateral flexible substituents are found to adopt a mean conformation more or less parallel to the mesogenic core. As a result, lateral chains are less disordered than terminal chains. Nematogens containing polyoxyethylene ether (POE) chain as a lateral crown ether and terminal chain(s) have been... 

Formula A complex mixture of polyoxyethylene ethers of mixed partial oleic esters of sorbitol anhydrides Density 1.06-1.llOgml-1 Volatility High... 

This paper is largely confined to the alkyl and aryl polyoxyethylene ethers, as these form series variable in both hydrophobic and hydrophilic chain length, and hence HLB, with minimal structural variation. 

Studies with homologous series of alkyl and aryl polyoxyethylene ethers... 

The difficulty with HLB as an index of physicochemical properties is that it is not a unique value, as the data of Zaslavsky et al. (1) on the haemolytic activity of three alkyl mercaptan polyoxyethylene derivatives clearly show in Table 1. Nevertheless data on promotion of the absorption of drugs by series of nonionic surfactants, when plotted as a function of HLB do show patterns of behaviour which can assist in pin-pointing the necessary lipophilicity required for optimal biological activity. It is evident however, that structural specificity plays a part in interactions of nonionic surfactants with biomembranes as shown in Table 1. It is reasonable to assume that membranes with different lipophilicities will"require" surfactants of different HLB to achieve penetration and fluidization one of the difficulties in discerning this optimal value of HLB resides in the problems of analysis of data in the literature. For example, Hirai et al. (8 ) examined the effect of a large series of alkyl polyoxyethylene ethers (C4,C0, Cj2 and C 2 series) on the absorption of insulin through the nasal mucosa of rats. Some results are shown in Table II. 

The most common surfactants for analytical applications are nonionic (polyoxyethylene glycol monoethers, polyoxyethylene methyl- -alkyl ethers, t-octylphenoxy polyoxyethylene ethers, and polyoxyethylene sorbitan esters... 

Silica Nanoparticles. The base-catalyzed hydrolysis of silicon aikoxides in microemulsions produces nanoparticles (20-39). Aqueous ammonia has been used primarily as the base, with AOT and nonionic polyoxyethylene ethers as the main surfactants. Figure 2.2.6 presents a flow diagram for the synthesis of pure silica (23-32) the microemulsion is first prepared and then the alkoxide is added. As can be seen from Table 2.2.1, the microemulsions include the systems AOT/ isooctane/water/ammonia, AOT/toluene/water/ammonia, NP-5/cyclohexane/water/ ammonia, and NP-4/heptane/water/ammonia. Typical reaction times are l -5 days. Various modified silica nanoparticles have also been prepared, including hydropho-... 

A number of works investigated the interaction between niosomes and human skin. With niosomes prepared from Ci2 alcohol polyoxyethylene ether and cholesterol, vesicular structures of about 100 nm size have been observed between the first and second layers of human corneocytes 48 h after incubation as well as in the deeper strata of the skin [37], The authors concluded that the structures visualized in the deeper regions could be vesicles reorganized from individual molecules that penetrated the skin. In another study, electron micrographs illustrated that niosomes containing surfactants and cholesterol affected only the most superficial corneocytes. Moreover, two-photon fluorescence microscopy confirmed that fluorescent probe encapsulated in niosomes was confined to the intercellular spaces within the apical stratum corneum layers [56]. 

A plot of the temperatures required for clouding versus surfactant concentration typically exhibits a minimum in the case of nonionic surfactants (or a maximum in the case of zwitterionics) in its coexistence curve, with the temperature and surfactant concentration at which the minimum (or maximum) occurs being referred to as the critical temperature and concentration, respectively. This type of behavior is also exhibited by other nonionic surfactants, that is, nonionic polymers, // - a I k y I s u I Any lalcoh o I s, hydroxymethyl or ethyl celluloses, dimethylalkylphosphine oxides, or, most commonly, alkyl (or aryl) polyoxyethylene ethers. Likewise, certain zwitterionic surfactant solutions can also exhibit critical behavior in which an upper rather than a lower consolute boundary is present. Previously, metal ions (in the form of metal chelate complexes) were extracted and enriched from aqueous media using such a cloud point extraction approach with nonionic surfactants. Extraction efficiencies in excess of 98% for such metal ion extraction techniques were achieved with enrichment factors in the range of 45-200. In addition to metal ion enrichments, this type of micellar cloud point extraction approach has been reported to be useful for the separation of hydrophobic from hydrophilic proteins, both originally present in an aqueous solution, and also for the preconcentration of the former type of proteins. 

Comforth JW et al (1955) Antituberculous effects of certain surface-active polyoxyethylene ethers Brit J Pharmacol 10 73-86... 

In view of their solubilizing effects and also their potential to change membrane permeability, surfactants have been considered as absorption enhancers, again mostly in animals. Polyoxyethylene ethers have been shown to enhance gastric or rectal absorption of linco-mycin, penicillin, cephalosporins, and fosfomycin in rats and rabbits. In rats, colonic absorption of interferon-alpha is increased from 3 to 8% by polyoxyethylene esters of oleic acid and oleic acid glycerides. 

Harvey, R.D. Barlow, D.J. Lawrence, M.J. Heenan, R.K. The effect of electrolyte on the morphology of vesicles composed of the dialkyl polyoxyethylene ether surfactant 2CigEi2. Chemistry and Physics of Lipids 2005,133, 27-36. 

A wide variety of this group of surfactants is commercially available. They include some of the Tritons (alkyl phenol additives, as far as they are non-ionic). Tweens (sorbitan fatty acid ester polyoxyethylene ethers). Spans (sorbitan fatty acid esters) and alkyl polyoxyethylenes (C Ej, where n and x stand for the number of CH2- or CH3-. and CHjO-groups in the hydrophobic and hydrophilic parts of the molecule, respectively). Given our interest in the fundamentals we shall emphasize only the last-mentioned group, and only when n and x are sharply defined emd the two moieties are either linear or branched in a defined way. Unless specified otherwise, there is an OH-group at the end of the E-chain. Notwithstanding the non-ionic nature of these molecules, micelles sometimes appear to cany a (low) charge probably caused by preferential uptake of ionic species. 

Many other polyoxyethylene ethers are commercially available and are also used as surfactants. In addition to their surfactant properties, the series of polyoxyethylene ethers with lauryl side chains, e.g. nonoxynol 10, are also widely used as spermicides. 

More interestingly, worm-like micelles without endings were spotted in 0.37 wt % CTAB solutions containing 3.0 wt % of NaBr electrolyte (see section 5.3). Micelles formed by 11-ferrocenylundecyl polyoxyethylene ether were positively stained with osmium tetroxide. The PEG-part then turned black and the ferrocene-undecane part turned out as white featureless spots. The result is again similar to negative staining as no defined osmium ring was detectable. 

Brij [ICI]. TM for a series of emulsifiers and wetting agents developed for use in emulsions of high alkalinity or acidity. They are polyoxyethylene ethers of higher aliphatic alcohols. Soluble in water and lower alcohols. Insoluble in coal tar hydrocarbons. 

Antituberculous effects of certain surface-active polyoxyethylene ethers, J. W. Cornforth, P. D Arcy Hart, G. A. Nicholls, R. J. W. Rees and J. A. Stock, Br. J. 

Nonionic polyoxyethylene ethers Anionic sodium laurylsulfate Cationic quaternary ammonium compounds Bile salts... 

The toxicity of ionic surfactants does restrict their use as drug-delivery vehicles, however. Nonionic surfactants are less toxic and therefore the neutral polyoxyethylene ethers or the combination of cholesterol with certain glyceryl-containing surfactants demonstrated to form vesicles is more interesting from a pharmaceutical point of view. The resultant nonionic vesicles have been termed niosomes (Hillery, 1998b). 

The enhancement of enantioselectivity cannot be an effect of solubility because water-soluble substrates gave enhanced activities but no enantioselectivity increase [54], Acylation of PPM ((2S,4S)-4-diphenylphosphino-2-diphenylphosphinomethyl-pyrrolidine) with the chlorocarbonic ester of alkyl polyoxyethylene ethers (Brij 4)... 

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