Anionic surfactants ether carboxylates

Some special salts of ether carboxylic acids are also described. Chloro-hexidine salts are made by neutralization of chlorohexidine base by an ether carboxylic acid having antibacterial and surfactant properties [47]. Chitosan salts of ether carboxylic acids which are tolerant of anionics and can be used as hair conditioners are also mentioned [48]. 

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. 

The reaction product with monoethanolamine acts as a thickening agent [41,101] and with alcohols as an emollient [40]. Also reaction products with amino acids and oligo- or polypeptides for use in cosmetic formulations are known [43]. Sorbitan esters from ether carboxylates are described as emulsifiers or mild surfactants in cosmetic formulations [39] and alkyl ether carboxylic acid taurides as nonirritant anionic surfactants for cosmetic cleaners in particular [44]. Using unsaturated ether carboxylates it is possible to make viscous formulations based on combinations of unsaturated and saturated ether carboxylates [111]. Highly purified alkyl ether carboxylates based on alcohol ethoxylates with low free alcohol content have also been described [112]. 

Ether carboxylates are used not only in powdered detergents but in liquid laundry detergents for their hard water stability, lime soap dispersibility, and electrolyte stability they improve the suspension stability and rheology of the electrolyte builder [130,131]. Formulations based particularly on lauryl ether carboxylate + 4.5 EO combined with fatty acid salt and other anionic surfactants are described [132], sometimes in combination with quaternary compounds as softeners [133,163]. Ether carboxylates show improved cleaning properties as suds-controlling agents in formulations with ethoxylated alkylphenol or fatty alcohol, alkyl phosphate esters or alkoxylate phosphate esters, and water-soluble builders [134]. 

The use of alkyl ether carboxylates in manual dishwashing agents was described in 1966 [136]. Subsequently several patents mention combinations of alkyl ether carboxylates with aminoxides [137,142], betaines [138,139,142], different anionic surfactants [140], quaternary compounds [141], alkylpolyglucoside [142], and polyhydroxy fatty acid amide [143]. In all cases the ether carboxylates are used to improve mildness and to achieve good cleaning and lathering properties. 

Studies on mechanisms are described by Balzer [192]. In the case of anionics the residual oil in the injection zone is removed via displacement into the adjacent reservoirs ether carboxylates show their good adaptation to differences in temperature and salinity. Further it was found from interfacial tension measurements, adsorption and retention studies, and flooding tests that use of surfactant blends based on ether carboxylates and alkylbenzensulfonates resulted... 

In comparison with other anionics, little has been published concerning methods of analysis of ether carboxylates. Gerhardt et al. [238] investigated the analytical determination of ether carboxylic acids in reaction mixtures obtained by reaction of nonylphenol ethoxylates with sodium chloroacetate as well as by cyanoethylation by different methods. Several methods, used for other surfactants as well [239], can be used for ether carboxylates. 

In the negative FIA-MS spectra, the sulfate, phosphate and carboxylate of these anionic alkylphenol ether derivatives in parallel to the aliphatic ethoxy surfactants show equally spaced signals with Am/z 44. However, according to the ionisation method applied—APCI or ESI in the negative or positive mode—and also that observed in the ionisation process of AES, equally spaced signals came either from the anionic compounds themselves or from the alkylphenol ethers... 

Several other anionic surfactants are commercially available, such as sulfosuccinates, isethionates, and taurates, and these are sometimes used for special applications. The carboxylates and sulfates are sometimes modified by the incorporation of a few moles of ethylene oxide (referred to as ether carboxylates and ether sulfates, respectively). 

The major subgroups of anionic surfactants include the alkali carboxylates (soaps), sulfates, sulfonates, and to a smaller degree, phosphates. The esterification of alcohol with sulfuric acid yields probably the best-studied surfactant, sodium dodecylsulfate or SDS. SDS, a sulfate ester, is an extremely effective emulsifier because of its high-electrostatic repulsion. Other sulfates are, for example, sulfated esters from fatty acids, sulfated ethers, and sulfated fats and oils. Sulfonates stem from the reaction of sulfonic acid with suitable substrates. Members of the class of sulfonates are, for example, sulfonic acid salts or aliphatic sulfonates. Other anionic surfactants include substances such as carboxylated soaps and esters of phosphoric acid. 

Dodiflood Brands. [HoechstAG] Ether sulfonates, ether carboxylates anionic surfactants for enhanced oil recovery and miooemulsion flooding. 

Acylated amino acids are known as anionic surfactants for a long time. Besides ether carboxylates mentioned above, sarcosinates (N-methylgycinates) is the most known type of mild "cryptoanionic" surfactants synthesised by direct reaction between saturated or unsaturated fatty acid halides and sarcosine in aqueous alkali [10, 11,74] ... 

Chem. Descrip. Fatty alcohol polyglycol ether carboxylic acid Me Nature Anionic Uses Surfactant for industrial cleaning Properties Liq, HLB 12.5 93% cone. 

Chem. Descrip. Nonylphenol polyglycol ether carboxylate Ionic Nature Anionic Uses Surfactant for agric, formulations Hostapal 3634 Highly Cone. [Clariant/Functional Chems.)... 

TABLE 6 HPLC Analysis of Ether Carboxylate Anionic Surfactants... 

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