Polyoxyethylene, oxidation

The polyoxyethylene group is obtained by addition of ethylene oxide to fatty alcohols, mostly with an alkalic catalyst such as NaOH or NaOCH3, giving a broad polyoxyethylene oxide distribution. For special applications the ethoxyl-ation can be catalyzed by Lewis acids [11] to achieve a narrow range distribution. Other narrow range catalysts can also be used to improve certain properties. 

Surfactants Sodium lauryl sulfate Polyoxyethylene oxide-9 ethers Solubilization of proteins/peptides Perturbation of membrane layers Extraction of membrane proteins and lipids... 

In the case of CnDMPOs, a class of non-ionic surfactants characterized by a small hydrophilic head, with reduced steric influence, even with a semipolar character [22], the more hydrophobic tail of C12DMPO enhances the hystheresis. With CiEjs the situation is more complicated the steric effect of polyoxyethylene oxide chains is not negligible, producing a significant antagonistic effect in the adsorption on the solid. 

The olfines contain acetylenic alcohol and acetylene diol. These compounds are basically acetylene-based polyoxyethylene oxide surfactants. Acetylenic alcohols themselves are highly volatile surfactants. An example of an acetylenic alcohol is propargyl alcohol, also known as propyn-l-ol. Acetylenic nonionic surfactants and their methods of synthesis have been described in detail (79). 

Three types of multiple emulsions may be distinguished [16] (Figure 12.11). This classification is based on the predominance of the multiple emulsion droplet type. Using isopropyl myristate as the oil phase, 5% Span 80 to prepare the primary W/O emulsion, and various surfactants to prepare the secondary emulsion, three main types of multiple emulsions were observed [16] Type A droplets contained on a large internal droplet, similar to that observed by Matsumoto et al. [17]. This type was produced when polyoxyethylene oxide (4) lauryl ether (Brij 30) was used as secondary emulsifier at 2%. Type B droplets contained several small internal droplets. These were prepared using 2% polyoxyethylene (16.5) nonylphenyl ether (Triton X-165). Type C drops entrapped a large number of small internal droplets. These were prepared using a 3 1 Span 80-Tween 80 mixture. 

Polysorha.tes. Polyoxyethylene sorbitan esters [9005-63-4] are formed from the reaction of sorbitol esters with ethylene oxide. These emulsifiers are almost always employed in combination with sorbitan esters and are used in the same appHcations (36). 

Ethoxyl tion. Base-cataly2ed ethoxylation of aUphatic alcohols, alkylphenols, and fatty acids can be broken down into two stages formation of a monoethoxy adduct and addition of ethylene oxide to the monoadduct to form the polyoxyethylene chain. The sequence of reactions is shown in equations 20—22 ... 

Number of ethylene oxide groups in esterified polyoxyethylene (POE). See Table 1. 

Ethoxylated Anhydrosorbitol Esters. Ethoxylation of sorbitan fatty acid esters leads to a series of more hydrophilic surfactants (Table 19). All hydroxyl groups of sorbitan can react with ethylene oxide. The stmcture of the principal component of a nominal polyoxyethylene (20) sorbitan monostearate illustrates the composition of these products, where w x y z = 20. 

Polyall lene Oxide Block Copolymers. The higher alkylene oxides derived from propjiene, butylene, styrene (qv), and cyclohexene react with active oxygens in a manner analogous to the reaction of ethylene oxide. Because the hydrophilic oxygen constitutes a smaller proportion of these molecules, the net effect is that the oxides, unlike ethylene oxide, are hydrophobic. The higher oxides are not used commercially as surfactant raw materials except for minor quantities that are employed as chain terminators in polyoxyethylene surfactants to lower the foaming tendency. The hydrophobic nature of propylene oxide units, —CH(CH2)CH20—, has been utilized in several ways in the manufacture of surfactants. Manufacture, properties, and uses of poly(oxyethylene- (9-oxypropylene) have been reviewed (98). 

In a typical case, ethylamine is allowed to react with ethylene oxide to produce N-ethyldiethanolamine (5). The latter is then treated with additional ethylene oxide to afford N,N-di(polyoxyethylene)ethylamine (6) where the sum a -t b is 3. This material is then stirred at room temperature for 3 h with toluenesulfonyl chloride and powdered sodium hydroxide in dioxane solution. After filtration and Kugelrohr distillation, N-eth-ylmonoaza-15-crown-5 is isolated in 75% yield as illustrated below in Eq. (4.7). 

In order to obtain anionic polyoxyethylene phosphate surfactants, either the terminal hydroxy group of a polyoxyethylated hydrophobic substance is reacted with a phosphorylating agent or a phosphate ester is oxalkylated. Most often aliphatic and aliphatic-aromatic alcohols are first treated with an alkylene oxide and afterward with one of the phosphorylating agents, such as P4OI0, POCl3, phosphoric acid, or polyphosphoric acid [39-48]. 

The stability characteristics of two different antiperspirant lotion systems were compared. Sample 1 represented an aqueous emulsion containing an aluminum salt. The internal phase consisted of stearyl alcohol and ethylene oxide reaction products, polyoxyethylene sorbitan monostearate and polyoxyethylene sorbitan tristearate. Methylcellulose was used as a stabilizer and bodying agent. Sample 2 represented a dispersion of magnesium aluminum silicate in an aqueous system containing aluminum ions. Because of its com-... 

The formation of peroxides and formaldehyde in the high-purity polyoxyethylene surfactants in toiletries has been shown to lead to contact dermatitis [31], Peroxides in hydrogenated castor oil can cause autoxidation of miconazole [32], Oxidative decomposition of the polyoxyethylene chains occurs at elevated temperature, leading to the formation of ethylene glycol, which may then be oxidized to formaldehyde. When polyethylene glycol and poloxamer were used to prepare solid dispersions of bendroflumethiazide, a potent, lipophilic diuretic drug, the drug reacted with the formaldehyde to produce hydroflumethiazide [33],... 

In many polymerizations cyclic material is produced by a concurrent backbiting reaction as linear polymer is formed. For example dioxan Is formed In the cationic polymerization of ethylene oxide to polyoxyethylene, and polyoxyethylene can be degraded to... 

There is no molecular interaction between nonionic surfactants with an ethylene-oxide chain, i.e. Genapol and ethoxylated nonylphenols. Indeed, research by Nishikido (6) on polyoxyethylene laurylethers (5 < E.O. number < 49) has shown the ideal behavior (p12 = 0) of their mixtures. Likewise, Xia (7) has found very low p12 values for mixtures of ethoxylated fatty alcohols. 

HTAC cationic micelles also markedly enhance the CL intensity of fluorescein (FL) in the oxidation of hydrogen peroxide catalyzed by horseradish peroxidase (HRP) [39], However, no CL enhancement was observed when anionic micelles of sodium dodecyl sulphate (SDS) or nonionic micelles of polyoxyethylene (23) dodecanol (Brij-35) were used (Fig. 9). CL enhancement is attributed to the electrostatic interaction of the anionic fluorescein with the HTAC micelles. The local concentration of fluorescein on the surface of the micelle increases the efficiency of the energy transferred from the singlet oxygen (which is produced in the peroxidation catalyzed by the HRP) to fluorescein. This chemiluminescent enhancement was applied to the determination of traces of hydrogen peroxide. The detection limit was three times smaller than that obtained in aqueous solution. 

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