Carboxylates alkyl ether

FIG. 1 Influence of pH on the surface tension of some alkyl ether carboxylic acids. (Concentration 1 g/1, Ring method.) (From Ref. 57.)... 

TABLE 1 CMC and Apparent Degree of Ionization of Some Alkyl Ether Carboxylates CnH2n+10(CH2CH20)xCH2C00Na... 

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. 

FIG. 3 Lime soap dispersing power of some alkyl ether carboxylates compared to other surfactants (DIN 53903). AEC, alkyl ether carboxylate AMEC, amidether carboxylate CAPB, cocamidoproplylbetaine OEC, oleyl ether carboxylate SLES, sodium lauryl ether sulfate. % surfactant soap = % surfactant calculated on the soap needed to disperse the lime soap. (From Refs. 61 and 64.)... 

TABLE 5 Alkali Stability of Some Alkyl Ether Carboxylic Acids... 

Note. For potassium water glass the sodium salts of the alkyl ether carboxylic acids were used. TPPP, tetrapotassium pyrophosphate PS, potassium water glass. 

TABLE 8 Foam Properties of Some Alkyl Ether Carboxylates According to Ross and Miles... 

TABLE 10 Alkyl Ether Carboxylates RO(CH2CH20)xCH2COOH Survey of Properties Related to the Length of the Fatty Chain... 

In a patent survey [76] about shampoos over the period 1968-1978 the so-called cryptoanionic alkyl ether carboxylate based on tridecyl alcohol with 6.5 mol EO has been mentioned for a conditioning shampoo in combination with an amphoteric and cationic surfactant [77]. Because of the low interference with cationic surfactants no negative effect on the conditioning properties has been found [78]. 

TABLE 11 Survey of Physicochemical Properties of Alkyl Ether Carboxylates Compared to Other Surfactants... 

In combination with alkyl ether sulfates, a synergistic decrease of the irritation level of the ether sulfates and an improvement of the foam stabilization has been described [57,67,78]. A good compromise between mildness and foam properties could be achieved with lauryl ether carboxylic acid sodium salt with 10 mol EO [57,67]. In several articles examples of the use of alkyl ether carboxylates as cosurfactant in mild shampoos as well as bath and shower products have been described [57,69,79]. 

Besides the alkyl ether carboxylates the amidether carboxylates are used as mild surfactants in cosmetic formulations [35-37,68,69,71,80]. As described by Meijer [68,69], the ether carboxylate mixture derived from the monoethanol-amide of coconut oil is a mild product in shampoos and showerbaths, and the stearylmonoethanolamidether carboxylate an oil-in-water emulsifier for creams and lotions. The NDELA content of these products is below the detection level of 10 ppb because of the use of monoethanolamine and the further chemical reactions after amidation. 

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]. 

Besides the usual alkyl ether carboxylates and amidether carboxylates some special types have been developed for use in cosmetic formulations. These are based on fatty alcohol propyl ether diols [113] and fatty alcohol diols [26]. 

Low-foaming liquid or powdered machine detergents are described using a surfactant system prepared from naturally based raw materials with good biodegradability and detergent properties [135]. These formulations are based on 5-30% alkylpolyglucoside, 5-30% alkyl ether carboxylate, 5-35% soap, and 0-3% of another surfactant. 

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. 

In 1991 the use of amidether carboxylate in combination with anionics like alkanesulfonate, alkylbenzolsulfonate, and alkyl ether sulfate to improve mildness and foam properties in the presence of soil was described [72]. Later a comparison study of the use of alkyl ether carboxylate, amidether carboxylate, and cocamidopropylbetaine in concentrated dishwashing formulations showed, in addition to the above-mentioned properties, the advantage of ether carboxylates in the construction of highly active formulations [144]. 

A special application of the ether carboxylic acid in metalworking has been described by Schuster [46] a boric acid ester has been produced by condensation of boric acid, alkanolamine, and alkyl ether carboxylic acid, eventually combined with a fatty acid. This condensation product gives less Ca soap precipitation, good anticorrosion effect, better removability of residues, and cleaner apparatus than the condensation product using only fatty acid. 

Separation of ionic and nonionic compounds of alkyl ether carboxylates can be done by reverse phase ion pair chromatography [241]. 

The mildness of alkyl ether carboxylates increases with increased length of the fatty chain or the EO degree [57,78,250] (see Table 12). 

Besides the case of the alkyl ether carboxylates, it has been found that amid-ether carboxylates show similar dermatological properties [68,79,80]. 

FIG. 7 Skin irritation according to the human patch test of alkyl ether carboxylic acids compared to other mild cosurfactants. CFTA-names 1, cocamidopropylbetaine 2, sodium PEG-6 cocamide carboxylate 3, sodium laureth-11 carboxylate 4, cocoamphocarboxypropionate 5, protein hydrolyzate 6, disodium laureth-3 sulfo-succinate SLES, sodium laureth sulfate. (From Ref. 68.)... 

Skubla [9] has designed a group contribution scheme which applies for various homologous series. His method relies on eq. 6.2.1 where both coefficients a0 and a have to be derived from group contributions and with respect to Nc. The model applies for n-alkanes, 1-alkenes, n-alkylcyclopentanes and n-alkylcyclohexanes, alkylbenzenes, 1-bromoalkanes, 1-alkanols, di-n-alkyl ethers, carboxylic acids and esters, 1-alkanethiols, 1-aminoalkanes, dialkylamines, alkaneamides, and some... 

Synonyms PEG-9 C12-15 alkyl ether carboxylic acid, cetyl ester PEG 450 Cl2-15 alkyl ether carboxylic acid, cetyl ester POE (9) Cl2-15 alkyl ether carboxylic acid, cetyl ester... 

Cl 1-15 pareth-7 carboxylic acid CAS 68954-90-5 (generic) 246159-57-9 Synonyms Pareth-15-7 carboxylic acid PEG-7 Cl 1-15 alkyl ether carboxylic acid POE (7)... 

Cl 1-15 alkyl ether carboxylic acid Classification Organic acid Formula R(OCH2CH2)nOCH2COOH, R rep. Cl 1-15 alkyl group, avg. n = 6... 

Synonyms PEG-8 Cl 2-13 alkyl ether carboxylic acid POE (8) C12-13 alkyl ether carboxylic acid... 

PEG-5 Cl2-15 alkyl ether. See Cl2-15 pareth-5 PEG-8 Cl 2-15 alkyl ether. See Cl 2-15 pareth-8 PEG-7 Cl 1-15 alkyl ether carboxylic acid. See Cl 1-15 pareth-7 carboxylic acid PEG-5 Cl2-13 alkyl ether carboxylic acid. See Cl2-13 pareth-5 carboxylic acid PEG-8 Cl2-13 alkyl ether carboxylic acid. See Cl 2-13 pareth-8 carboxylic acid PEG-7 Cl2-15 alkyl ether carboxylic acid. See C12-15 pareth-7 carboxylic acid PEG-8 C12-15 alkyl ether carboxylic acid. See C12-15 pareth-8 carboxylic acid PEG-8 C14-15 alkyl ether carboxylic acid PEG 400 C14-15 alkyl ether carboxylic acid. See C14-15 pareth-8 carboxylic acid PEG-9 C12-15 alkyl ether carboxylic acid, cetyl ester PEG 450 C12-15 alkyl ether carboxylic acid, cetyl ester. See Cetyl C12-15 pareth-9-carboxylate... 

C12-15-pareth-9-carboxylate PEG-7 C11-15 alkyl ether carboxylic acid, sodium salt. See Sodium C11-15 pareth-7 carboxyiate... 

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