Nonionic ethers

The most extensive group of ether surfactants is that of polyethoxylated long-chain alcohols and related ethoxylated products considered, in view of their practical importance, in a separate section. Other ether nonionics of importance are polypropylene glycols, propoxylated alcohols, block-copolymers of ethylene oxide and propylene oxide, block-copolymers of ethylene oxide and butylene oxide [8, 16-20], block-copolymers having a hydrophobic polydimethylsiloxane moiety [19, 21], as well as alkyl polyglycerides, alkyl polyglycosides, derivatives of maltose and other saccarides. 

Addition of propylene oxide to 1,2-propylene glycol results in polypropylene glycol (PPG)  

Addition of glycidol (2,3-epoxypropanol-1) to long-chain alcohols in the presence of alkaline catalyst results in monoglycerine and polyglycerine ethers  

A present-day boom of interest to alkyl polyglycosides APG, known however for hundred years, is caused by several reasons finding of technologically acceptable and cost-effective ways of their synthesis, availability of renewable resources (starch, treacle and alcohols of natural origin), environmental compatibility, high surface activity, excellent usage and dermatological properties [4-6 24]. 

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Properties are highly dependent upon the polarity of the substituent. Water-solubility is obtained at a DS value of about 1 for nonionic ethers. If hydro-phobic ether groups predominate, the water solubility may disappear at a DS levels above 2 [5]. Methylcellulose is in fact soluble up to about 1.8, whereas ethylcellulose only up to 1.2—1.4 (not available commercially). Introducing polar groups (carboxyls, hydroxyls) of course strongly increases hydrophilicity. 

The effect of solutes is usually expressed as the depression in the gelation temperature or cloud point caused by a given concentration of additive or by the concentration of added solute tolerated by the polymer concentration. From the data available in many classical articles [1, 5-7,9,10,12], the cation tolerance for nonionic ethers seems to follow the order ... 

Evafanol . [NiccaUSA] Nonionic ether Qqie urethane polymer softening/and-static agent for nylon hosiery. 

A systematic study in rats, in which the absorption-enhancing effects of a number of surfactants were compared, was reported by Hirai et al (1981a,b). The promoting effect of several nonionic surfactants was paralleled by their ability to lyse red blood cells and to release protein from the nasal mucosa of rats. Bile salts, however, were found to be less lytic and damaging to the rat nasal mucosa than nonionic ether-type surfactants. Generally, a positive correlation was observed between the damaging effect on the biomembrane and the absorption-promoting effect of the surfactants. 

The values of the conformational exponent of nonionic ethers (a = 1) is indicative of expanded or freely-draining coils. The addition of electrolytes would cause the... 

In this section the influence of micelles of cetyltrimethylammonium bromide (CTAB), sodium dodecylsulfate (SDS) and dodecyl heptaoxyethylene ether (C12E7) on the Diels-Alder reaction of 5.1a-g with 5.2 in the absence of Lewis-add catalysts is described (see Scheme 5.1). Note that the dienophiles can be divided into nonionic (5.1a-e), anionic (5.If) and cationic (5.1g) species. A comparison of the effect of nonionic (C12E7), anionic (SDS) and cationic (CTAB) micelles on the rates of their reaction with 5.2 will assess of the importance of electrostatic interactions in micellar catalysis or inhibition. 

Anionic surfactants are the most commonly used class of surfactant. Anionic surfactants include sulfates such as sodium alkylsulfate and the homologous ethoxylated versions and sulfonates, eg, sodium alkylglycerol ether sulfonate and sodium cocoyl isethionate. Nonionic surfactants are commonly used at low levels ( 1 2%) to reduce soap scum formation of the product, especially in hard water. These nonionic surfactants are usually ethoxylated fatty materials, such as H0CH2CH20(CH2CH20) R. These are commonly based on triglycerides or fatty alcohols. Amphoteric surfactants, such as cocamidopropyl betaine and cocoamphoacetate, are more recent surfactants in the bar soap area and are typically used at low levels (<2%) as secondary surfactants. These materials can have a dramatic impact on both the lathering and mildness of products (26). 

Polyoxyethylene Surfactants. Polyoxyethylene-solubilized nonionics (ethoxylates) were iatroduced ia the United States as textile chemicals shordy before 1940. The solubiUty of these compounds derives from recurring ether linkages ia a polyoxyethylene chain... 

Properties. Ethyl cellulose [9004-57-3] (EC) is a nonionic, organo-soluble, thermoplastic cellulose ether, having an ethyl DS in the range of 2.2-2.7. Actually, EC is water-soluble at DS 1.2, but only those products that are thermoplastic and soluble in organic solvents are of commercial importance, because of thek abiUty to form tough, stable films. Above a DS of about 2.5, EC is soluble in many nonpolar solvents. 

Properties. Hydroxypropylcellulose [9004-64-2] (HPC) is a thermoplastic, nonionic cellulose ether that is soluble in water and in many organic solvents. HPC combines organic solvent solubiUty, thermoplasticity, and surface activity with the aqueous thickening and stabilising properties characteristic of other water-soluble ceUulosic polymers described herein. Like the methylceUuloses, HPC exhibits a low critical solution temperature in water. 

Liquid Third Phase. A third Hquid with coUoidal stmcture has been a known component in emulsions since the 1970s (22) for nonionic surfactants of the poly(ethylene glycol) alkylaryl ether type. It allows low energy emulsification (23) using the strong temperature dependence of the coUoidal association stmctures in the water—surfactant—hydrocarbon systems. 

Chemical Designations - Synonyms Ethoxylated dodecyl alcohol, Ethoxylated lauryl alcohol, Poly(oxyethyl)dodecyl ether, Poly(oxyethyl) lauryl ether, Tergitol Nonionic TMN Chemical Formula CijHu0(CH2CH20) CHi CH OH n=6-10 (average). 

Chemical Designations - Synonyms Ethoxylated pentadecyl alcohol, Poly(oxyethyl) pentadecyl ether, Terrgitol nonionic 45-S-lO Chemical Formula C]3H3i0(CH2CH20) CH2CH20H n=10 (average). Observable Characteristics - Physical State (as normally shipped) Liquid Color Colorless Odor Mild, pleasant. 

Chemical Designations - Synonyms Ethoxylated myristyl alcohol, Ethoxylated tetradecyl alcohol, Poly(oxyethil) myristyl ether, Poly(oxyethil) tetradecyl ether, tergtol Nonionic 45-S-lO Chemical Formula C,41X2,0 (CH2CH20) CH2CH20H n=5 (average). 

Poloxamers are used primarily in aqueous solution and may be quantified in the aqueous phase by the use of compleximetric methods. However, a major limitation is that these techniques are essentially only capable of quantifying alkylene oxide groups and are by no means selective for poloxamers. The basis of these methods is the formation of a complex between a metal ion and the oxygen atoms that form the ether linkages. Reaction of this complex with an anion leads to the formation of a salt that, after precipitation or extraction, may be used for quantitation. A method reported to be rapid, simple, and consistently reproducible [18] involves a two-phase titration, which eliminates interferences from anionic surfactants. The poloxamer is complexed with potassium ions in an alkaline aqueous solution and extracted into dichloromethane as an ion pair with the titrant, tet-rakis (4-fluorophenyl) borate. The end point is defined by a color change resulting from the complexation of the indicator, Victoria Blue B, with excess titrant. The Wickbold [19] method, widely used to determine nonionic surfactants, has been applied to poloxamer type surfactants 120]. Essentially the method involves the formation in the presence of barium ions of a complex be-... 

Higher molecular primary unbranched or low-branched alcohols are used not only for the synthesis of nonionic but also of anionic surfactants, like fatty alcohol sulfates or ether sulfates. These alcohols are produced by catalytic high-pressure hydrogenation of the methyl esters of fatty acids, obtained by a transesterification reaction of fats or fatty oils with methanol or by different procedures, like hydroformylation or the Alfol process, starting from petroleum chemical raw materials. 

Ethylene oxide is an important intermediate chemical not only for the production of nonionic surfactants like fatty alcohol ethoxylates, alkylphenol ethoxy lates, or propylene oxide/ethylene oxide block copolymers, but also for manufacturing of anionic surfactants like alcohol ether sulfates. 

Subacute and chronic toxicity of alcohol and alcohol ether sulfates has been extensively tested in several animals and sometimes humans. The duration of the tests was in some cases as long as 2 years. When administered below the toxic amount no specific damages were observed in any of the species tested [333]. No severe side effects were observed in the study by Swisher, carried out with volunteers who ingested considerable amounts of anionic and nonionic surfactants over long periods [348]. Similarly, the effects produced by the intake of daily doses of 1 g of alcohol sulfate per person over 8 weeks [349],... 

The conversion of the nonionic to the ether carboxylate depends, among other things, on... 

Ether carboxylates with two alkyl chains are produced by reacting nonionics with dichloroaceticacid and a 50% solution of NaOH in water under vacuum at temperatures between 115°C and 120°C [28]. Compounds of the type... 

Gerhardt et al. [34] described three possible ways to prepare alkylphenol-polyglycol ether carboxylates, namely, the method with NaOH and SMCA, the method by oxidation by means of oxygen, and the method whereby the nonionic reacts with acrylonitrile followed by hydrolyses with hydrochloric acid. The synthesis with acrylonitrile forms in contrast to the other two methods, carboxyethylated compounds with the general formula... 

The ether carboxylic acids are weakly dissociated [49], exhibiting nonionic behavior at low pH and anionic behavior at high pH. Due to this dual nonionic and anionic character a good emulsification effect can be achieved [66]. For many applications a high carboxymethylation of 80-90% is preferred [64] to obtain the wanted properties. 

The surface-active properties of ether carboxylates have been compared with soaps as well as with those of nonionic and anionic surfactants in addition, the influence of fatty chain and degree of ethoxylation has been investigated. 

Van Paassen [57], Stroink [61], and Meijer [64] described the influence of fatty chain, ethoxylation degree, and pH on the surface tension. It can be concluded that the ether carboxylates behave at low pH as nonionic surfactants with a lower surface tension than at higher pH, where they behave more as anionic surfactants (Fig. 1). Furthermore a higher EO chain or a shorter fatty chain increases the surface tension. 

It has been found that the CMC values are higher and the micelle aggregation numbers smaller than those of the corresponding nonionic surfactants. The CMC increases with increasing EO chain, which is, according to the authors, opposite to the results for sodium alkyl ether sulfate. 

From the apparent ionization degree it was concluded that the EO chain probably behaves as part of the headgroup. As with Aalbers [49], a low surface charge of the sodium alkyl ether carboxylate micelles was mentioned. The micelle aggregation number N increases with the C chain much more than for the corresponding nonionic surfactants. In the case of C8 there was no influence of temperature. A small decrease was found with increasing EO, but much smaller than in the case of nonionics. 

Later their use in the pretreatment of cotton was described, i.e., mercerizing [169], boiling off [8,170], and bleaching [170,171], For wool washing and wool treatment ether carboxylates have also been mentioned the detergent effect is better than that of the corresponding nonionics, a pleasant feeling is achieved and there is no corrosion on metal [172],... 

Ether carboxylates have also been used in formulations with ethoxylated amines, ethoxylated and propoxylated nonionics, or ethoxylated castor oil and alkanolamides for one-bath dyeing or printing with cationic and anionic or disperse dyes [176],... 

Besides the use of anionics such as sulfonates and nonionics such as alkyl-phenol ethoxylates, in 1977 the use of ether carboxylates was also described [183] in terms of its excellent temperature, electrolyte, and hard water stability and low interfacial tension, especially in case of the C12-C14 ether carboxylic acid with 4.5 mol EO. 

Adsorption and retention studies of surfactants to sand in high-salinity reservoirs showed no differences between nonionics and ether carboxylates [185— 187] low retention and a positive behavior for good oil recovery has been found. 

Solubilization studies on crude oil by ether carboxylates combined with nonionics have been conducted in the presence of varying amounts of CaCl2 [194]. Good solubility can be obtained when the micellar size is 100 nm and is strongly dependent on the CaCl2 concentration. 

Results described in the literature have resulted in several patents, such as one for the improvement of the transport of viscous crude oil by microemulsions based on ether carboxylates [195], or combination with ether sulfate and nonionics [196], or several anionics, amphoterics, and nonionics [197] increased oil recovery with ether carboxylates and ethersulfonates [198] increased inversion temperature of the emulsion above the reservoir temperature by ether carboxylates [199], or systems based on ether carboxylate and sulfonate [200] or polyglucosylsorbitol fatty acid ester [201] and eventually cosolvents which are not susceptible for temperature changes. Ether carboxylates also show an improvement when used in a C02 drive process [202] or at recovery by steam flooding [203]. 

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