Ether sulfate , alcohol

Cosurfactant requirements can be minimized usiag a surfactant having a short-branched hydrophobe or a branched-alkyl substituent on an aromatic group (232,234) and a long ethoxy group chain (234). Blends of surfactants optimized for seawater or reservoir brine salinity include linear alkyl xylene sulfonate—alcohol ether sulfate mixtures (235). 

Anhydrous sulfonic acids, particularly linear alkylben2enesulfonic acids, are typically stored ia stainless steel containers, preferably type 304 or 316 stainless steel. Use of other metals, such as mild steel, contaminates the acid with iron (qv), causiag a darkening of the acid over time (27). The materials are usually viscous oils which may be stored and handled at 30—35°C for up to two months (27). AH other detergent-grade sulfonic acids, eg, alcohol sulfates, alcohol ether sulfates, alpha-olefin sulfonates, and alpha-sulfomethyl esters, are not stored owiag to iastabiUty. These are neutrali2ed to the desired salt. 

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. 

Table 6 shows a comparison of commercially produced C, 4 LAS samples in a current North American light-duty liquid (LDL) formulation containing more than 20% LAS together with alcohol ether sulfate (AES), amide, and hydrotrope. The highest viscosity is observed with the high 2-phenyl/low DATS sample, whereas the high 2-phenyl/high DATS sample had the lowest viscosity. The DATS provides the dual function of surfactant and hydrotrope. 

FIG. 36 Synergistic mixture of alkane- (paraffin) sulfonates (PS) and fatty alcohol ether sulfates (FAES). Cleaning effect in miniplate test at 50°C, tap water (12° German hardness), 0.075 g of active surfactant mixture per liter. 

APG, alkyl polyglucoside FAA, fatty acid alkanolamide FAEO, fatty alcohol ethoxylate FAES, fatty alcohol ether sulfate FAGA, fatty acid glucamide FAS, fatty alcohol sulfate LAS, linear alkylbenzenesulfonate SAS, secondary alkanesulfonate. 

Synthetic fibers washing (Alkylphenol ethoxylates,) fatty alcohol ethoxylates, alkane (olefine)-sulfonates, fatty alcohol (ether) sulfates, end-group-blocked fatty alcohol ethoxylates... 

V. Analysis of Alcohol Sulfates and Alcohol Ether Sulfates 278... 

As esters of sulfuric acid, the hydrophilic group of alcohol sulfates and alcohol ether sulfates is the sulfate ion, which is linked to the hydrophobic tail through a C-O-S bond. This bond gives the molecule a relative instability as this linkage is prone to hydrolysis in acidic media. This establishes a basic difference from other key anionic surfactants such as alkyl and alkylbenzene-sulfonates, which have a C-S bond, completely stable in all normal conditions of use. The chemical structure of these sulfate molecules partially limits their conditions of use and their application areas but nevertheless they are found undoubtedly in the widest range of application types among anionic surfactants. 

Alcohols used in the manufacture of alcohol and alcohol ether sulfates are obtained either by chemical treatment of fats and oils or by petrochemical processes from natural gas or crude oil. In either case the hydrocarbon chain ranging from 8 to 18 carbon atoms corresponding to the composition of coconut oil is the most desirable. 

Although widely used in the past and still used in special cases, the industrial sulfation with chlorosulfonic acid presents several problems which have caused the decline of this technique in favor of the more advantageous sulfation method with sulfur trioxide. These problems consist of evolution of the highly corrosive hydrogen chloride, heat transfer characteristics of the reaction, and the comparatively high level of chloride ion in the sulfated product compared with alcohol and alcohol ether sulfates obtained with sulfur trioxide. 

FIG. 1 Kinetics of the hydrolysis of sodium hexyl sulfate and several alcohol ether sulfates. 1, Sodium hexyl ether (1 PrO) sulfate, K = 0.0075 min1 2, sodium octyl ether (1 PrO) sulfate, AT, - 0.0071 min 1 3, sodium octyl ether (1 EO) sulfate, AT, = 0.0051 min1 and 4, sodium hexyl sulfate, AT, = 0.0037 min1. 

The addition of ethylene oxide to the alcohol causes a decrease in the melting point of the corresponding salt of the alcohol ether sulfate in comparison with the same alcohol sulfate. Weil et al. [65] prepared pure hexadecyl and octadecyl ether alcohols from the corresponding alkyl bromide and glycols with... 

Table 3 shows the melting points of several alcohol and alcohol ether sulfates. 

Salts of monovalent metals of alcohol and alcohol ether sulfates are soluble in water, with the solubility dependend on the cation and the chain length. Ammonium salts are more soluble than sodium salts and these are more soluble than potassium salts. On the other hand, sulfates with short hydrophobic chains are more soluble than those with longer chains but the short-chain molecules have a solubilizing effect on the more insoluble longer chain molecules [68], The solubility of sodium salts of different alcohol sulfates is shown in Fig. 2 and the solubility of sodium and potassium salts of dodecyl sulfate is compared. 

TABLE 3 Melting Points of Alcohol and Alcohol Ether Sulfates... 

Ethoxylation of the base alcohol always improves the solubility of the sulfate. As an example, sodium hexadecyl ether (2 EO) sulfate gives a clear 10% solution in water at 40°C, which becomes a viscous gel at 30°C [59]. Alcohol ether sulfates are also more soluble in organic solvents than the corresponding alcohol sulfates. Sodium hexadecyl and octadecyl ether (2 EO) sulfates are soluble at 1% concentration in lubricating oil, at 2.5% in benzene and chloroform, and at 5% in tetrachloroethylene, whereas alcohol-ethoxylated sulfates with 10 mol of ethylene oxide are soluble at 5% in lubricating oil [59]. 

As the concentration is increased, the viscosity of the solution generally increases, although not linearly, and may eventually undergo a sudden decrease. This is due to changes in the internal geometry of the surfactant molecules. At relatively low concentrations the alcohol ether sulfate solution consists of spheri-... 

The viscosity of alcohol sulfate and alcohol ether sulfate solutions is sensitive to the amount of byproducts contained in the solution. Putnik and McGuire [76] developed an empirical equation [Eq. (10)] relating the kinematic viscosity of a sodium C12-C16 alcohol sulfate to the weight percentages of free oil (FO), sulfate ion (S04), and chloride ion (Cl) ... 

Alcohol ether sulfate solutions are easily thickened by the addition of electrolytes and other surfactants, particularly alkanolamides, and even highly di-... 

Recently, patented ethoxylation catalysts have become available that can significantly narrow the ethylene oxide distribution of the alcohol ethoxylates used to obtain alcohol ether sulfates. These products are termed peaked alcohol ether sulfates whereas all others are termed conventional alcohol ether sulfates. Peaked alcohol ether sulfate solutions thicken more than those with a conventional ethylene oxide distribution [78]. Peaked alcohol ether sulfate solutions also exhibit behaviors different from those of conventional sulfates [79]. Smith [78] studied the viscosities of 15% sodium dodecyl ether sulfate solutions of both families with NaCl content between 2% and 10% at 25°C using a Brookfield model DVII viscometer at a shear rate of 2 s 1. The results are shown in Fig. 5 where the very different viscosities achieved are clearly observed. 

Table 19 shows the efficiencies and effectiveness of several alcohol and alcohol ether sulfates and Tables 20 and 21 give some values of surface tensions. 

---