Anionic surfactants sulfonates

A.lkyl Sulfosuccinate Half Asters. These detergents are prepared by reaction of maleic anhydride and a primary fatty alcohol, followed by sulfonation with sodium bisulfite. A typical member of this group is disodium lauryl sulfosucciaate [26838-05-1]. Although not known as effective foamers, these surfactants can boost foams and act as stabilizers when used ia combination with other anionic surfactants. In combination with alkyl sulfates, they are said to reduce the irritation effects of the latter (6). 

Three generations of latices as characterized by the type of surfactant used in manufacture have been defined (53). The first generation includes latices made with conventional (/) anionic surfactants like fatty acid soaps, alkyl carboxylates, alkyl sulfates, and alkyl sulfonates (54) (2) nonionic surfactants like poly(ethylene oxide) or poly(vinyl alcohol) used to improve freeze—thaw and shear stabiUty and (J) cationic surfactants like amines, nitriles, and other nitrogen bases, rarely used because of incompatibiUty problems. Portiand cement latex modifiers are one example where cationic surfactants are used. Anionic surfactants yield smaller particles than nonionic surfactants (55). Often a combination of anionic surfactants or anionic and nonionic surfactants are used to provide improved stabiUty. The stabilizing abiUty of anionic fatty acid soaps diminishes at lower pH as the soaps revert to their acids. First-generation latices also suffer from the presence of soap on the polymer particles at the end of the polymerization. Steam and vacuum stripping methods are often used to remove the soap and unreacted monomer from the final product (56). 

The surfactants (qv) used in the emulsion polymerization of acryUc or methacrylic monomers are classified as anionic, cationic, or nonionic. Anionic surfactants, such as alkyl sulfates and alkylarene sulfonates and phosphates, or nonionic surfactants, such as alkyl or aryl polyoxyethylenes, are most common. Mixed anionic nonionic surfactant systems are also widely utilized. 

Surfactants evaluated in surfactant-enhanced alkaline flooding include internal olefin sulfonates (259,261), linear alkyl xylene sulfonates (262), petroleum sulfonates (262), alcohol ethoxysulfates (258,261,263), and alcohol ethoxylates/anionic surfactants (257). Water-thickening polymers, either xanthan or polyacrylamide, can reduce injected fluid mobiHty in alkaline flooding (264) and surfactant-enhanced alkaline flooding (259,263). The combined use of alkah, surfactant, and water-thickening polymer has been termed the alkaH—surfactant—polymer (ASP) process. Cross-linked polymers have been used to increase volumetric sweep efficiency of surfactant—polymer—alkaline agent formulations (265). 

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). 

Carboxylate, sulfonate, sulfate, and phosphate ate the polar, solubilizing groups found in most anionic surfactants. In dilute solutions of soft water, these groups ate combined with a 12—15 carbon chain hydrophobe for best surfactant properties. In neutral or acidic media, or in the presence of heavy-metal salts, eg, Ca, the carboxylate group loses most of its solubilizing power. 

Cationic, anionic, and amphoteric surfactants derive thek water solubiUty from thek ionic charge, whereas the nonionic hydrophile derives its water solubihty from highly polar terminal hydroxyl groups. Cationic surfactants perform well in polar substrates like styrenics and polyurethane. Examples of cationic surfactants ate quaternary ammonium chlorides, quaternary ammonium methosulfates, and quaternary ammonium nitrates (see QuARTERNARY AMMONIUM compounds). Anionic surfactants work well in PVC and styrenics. Examples of anionic surfactants ate fatty phosphate esters and alkyl sulfonates. 

Alkyl benzene sulfonates (ABS). Branched-chain anionic surfactants. Slow to biodegrade. Seldom used. 

Linear alkyl benzene sulfonates (LAS). Straight-chain anionic surfactants. Somewhat slow to biodegrade. Most common surfactants in use. 

Surface-active compounds, especially the anionic surfactants, are derived from fossil raw materials as well as from recent raw materials. The portion of the biomass on the production of anionic surfactants is about 75% if the soap, the quantitatively most important anionic surfactant, is included. Considering only the synthetic surfactants, the syndets, the portion of fossil raw materials in the production of these surfactants, is about 75%. Without the lignosulfonates (and the petroleum sulfonates) this portion is about 90%. Due to strong efforts... 

Further auxiliary agents for the production of anionic surfactants are the sulfation and sulfonation agents oleum, chlorosulfonic acid, C1-S02-0H, air-S03 mixtures, air-S02 mixtures, sultones (especially 1,3-propanesultone (CH2—CH2—CH2—SO2), and isethionic acid (2-hydroxyethanesulfonic O-------------------1... 

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. 

In an extensive study by Read et al. [93], 10 anionic surfactants were evaluated for their ability to remove pyritic sulfur and ash from ultrafine Illinois no. 5 coal by flotation processes. The authors observed that of the commercially available surfactants, sodium dodecyl sulfate was the most effective on either a weight or a molar basis, followed by a linear AOS (average molweight 272) and alkylpolyethoxylated sulfonates. Of the noncommercial surfactants tested, -(E -b-dodecene-b-suIfonate (f0) was the most effective and better than any commercial surfactant on a dosage/recovery basis. 

The amount of residual sulfonate ester remaining after hydrolysis can be determined by a procedure proposed by Martinsson and Nilsson [129], similar to that used to determine total residual saponifiables in neutral oils. Neutrals, including alkanes, alkenes, secondary alcohols, and sultones, as well as the sulfonate esters in the AOS, are isolated by extraction from an aqueous alcoholic solution with petroleum ether. The sulfonate esters are separated from the sultones by chromatography on a silica gel column. Each eluent fraction is subjected to saponification and measured as active matter by MBAS determination measuring the extinction of the trichloromethane solution at 642 nra. (a) Sultones. Connor et al. [130] first reported, in 1975, a very small amount of skin sensitizer, l-unsaturated-l,3-sultone, and 2-chloroalkane-l,3-sultone in the anionic surfactant produced by the sulfation of ethoxylated fatty alcohol. These compounds can also be found in some AOS products consequently, methods of detection are essential. 

Also the a-ester sulfonates are less important today. In the Federal Republic of Germany, for example, the total production of surfactants was about 700,000 t/a in 1993. For a more detailed analysis of different types of surfactants, use must be made of data collected before the unification of Germany. In 1988 the consumption of surfactants in detergents was about 227,500 t/a, the consumption of anionic surfactants was about 116,000 t/a and less than 1000 t/a of a-sulfo fatty acid esters [5] (the values refer to German Detergent Law). 

Compared with the fatty alcohol sulfates, which are also oleochemically produced anionic surfactants, the ester sulfonates have the advantage that their raw materials are on a low and therefore cost-effective level of fat refinement. The ester sulfonates are produced directly from the fatty acid esters by sulfona-tion, whereas the fatty alcohols, which are the source materials of the fatty alcohol sulfates, have to be formed by the catalytic high-pressure hydrogenation of fatty acids esters [9]. The fatty acid esters are obtained directly from the fats and oils by transesterification of the triglycerides with alcohols [10]. 

The acute toxicity of ester sulfonates is mainly related to the length of the carbon chain of the fatty acid. The acute fish toxicity of tallow-based ester sulfonates is relatively high (LC0 = 0.4-0.9 mg/L) compared with coconut-based ester sulfonates (LC0 — 46 mg/L) [113]. In spite of this relatively high fish toxicity of the long-chain ester sulfonates both acute and long-term toxic effects can be excluded for normal environmental conditions. For example, the sum of all anionic surfactants in German rivers is stable on a level far below... 

There are four reasons why S03/air raised from sulfur is becoming the predominant sulfonation agent for the manufacture of high-quality anionic surfactants ... 

There are four main sulfonation reactor configurations applied worldwide to produce all kinds of top quality anionic surfactants from sulfur-based S03/air as the sulfonating agent. All these systems have proven and documented experience ... 

In the production of anionic surfactants, the analytical procedures to be adopted for quality control and/or assessment are of particular importance. Their reliability as well as their time and chemical demand is a fundamental topic for the economy and success of the surfactant production cycle. To this end the most important analyses to be done on the various types of anionic surfactants are outlined in Tables 15-19. Mention must be made of potentiometric titration of the sulfonic acid (whatever the processed feedstock), which allows one to obtain reliable results over a very short time. 

A fluid loss additive for hard brine environments has been developed [1685], which consists of hydrocarbon, an anionic surfactant, an alcohol, a sulfonated asphalt, a biopolymer, and optionally an organophilic clay, a copolymer of N-vinyl-2-pyrrolidone and sodium-2-acrylamido-2-methylpropane sulfonate. Methylene-bis-acrylamide can be used as a crosslinker [1398]. Crosslinking imparts thermal stability and resistance to alkaline hydrolysis. 

Ammonium salts of alkenyl succinic half-amides have teen described for use as corrosion inhibitors in oil and gas production technology to combat corrosion by media containing CO2, H2S, and elemental sulfur [1366]. The inhibitor composition may contain a dispersing agent, such as a low molecular weight or polymeric anionic surfactant like an alkylsulfonic acid or an alkyl-aryl sulfonic acid. 

AOT is an anionic surfactant complexed to the counterion, usually sodium. The water molecules in the intramicellar water pool are either free or bound to the interface. The bound water can interact with various parts of the surfactant. These interactions include hydrogen-bonding interactions with oxygen molecules on the sulfonate and succinate groups, ion-dipole interactions with the anionic surfactant headgroup and counterion, dipole-dipole interactions with the succinate group, and dispersive forces with the hydrocarbon tails. 

Fatty alcohol- (or alkyl-)ethoxylates, CoE, are considered to be better candidates for LLE based on their ability to induce rapid phase separation for Winsor II and III systems. (Winsor III systems consist of excess aqueous and organic phases, and a middle phase containing bicontinuous microemulsions.) However, C,E,-type surfactants alone cannot extract biomolecules, presumably because they have no net negative charge, in contrast to sorbitan esters [24,26,30,31]. But, when combined with an additional anionic surfactant such as AOT or sodium benzene dodecyl sulfonate (SDBS), or affinity surfactant, extraction readily occurs [30,31]. The second surfactant must be present beyond a minimum threshold value so that its interfacial concentration is sufficiently large to be seen by... 

CE has been used for the analysis of anionic surfactants [946,947] and can be considered as complementary to HPLC for the analysis of cationic surfactants with advantages of minimal solvent consumption, higher efficiency, easy cleaning and inexpensive replacement of columns and the ability of fast method development by changing the electrolyte composition. Also the separation of polystyrene sulfonates with polymeric additives by CE has been reported [948]. Moreover, CE has also been used for the analysis of polymeric water treatment additives, such as acrylic acid copolymer flocculants, phosphonates, low-MW acids and inorganic anions. The technique provides for analyst time-savings and has lower detection limits and improved quantification for determination of anionic polymers, compared to HPLC. 

Surfactants used as lubricants are added to polymer resins to improve the flow characteristics of the plastic during processing they also stabilise the cells of polyurethane foams during the foaming process. Surfactants are either nonionic (e.g. fatty amides and alcohols), cationic, anionic (dominating class e.g. alkylbenzene sulfonates), zwitterionic, hetero-element or polymeric (e.g. EO-PO block copolymers). Fluorinated anionic surfactants or super surfactants enable a variety of surfaces normally regarded as difficult to wet. These include PE and PP any product required to wet the surface of these polymers will benefit from inclusion of fluorosurfactants. Surfactants are frequently multicomponent formulations, based on petro- or oleochemicals. 

Both nonionic and anionic surfactants have been evaluated in this application (488,489) including internal olefin sulfonates (487, 490), linear alkylxylene sulfonates (490), petroleum sulfonates (491), alcohol ethoxysulfates (487,489,492). Ethoxylated alcohols have been added to some anionic surfactant formulations to improve interfacial properties (486). The use of water thickening polymers, either xanthan or polyacrylamide to reduce injected fluid mobility mobility has been proposed for both alkaline flooding (493) and surfactant enhanced alkaline flooding (492). Crosslinked polymers have been used to increase volumetric sweep efficiency of surfactant - polymer - alkaline agent formulations (493). 

As an anionic surfactant, a synthetic alkylate-base sulfonate containing about 60 % active material (Synacto 476) was used. To make it compatible with the injection water considered (composition in Table I) containing 1500 ppm Ca++ and Mg++ ions, a nonionic cosurfactant was combined with it, i.e. an unsaturated ethoxylated fatty alcohol with 8 ethylene oxide groups (Genapol). Their main characteristics and properties are listed in Table II. 

Bhat et al. [199] used complexation with the bis(ethylenediamine) copper (II) cation as the basis of a method for estimating anionic surfactants in fresh estuarine and seawater samples. The complex is extracted into chloroform, and copper is measured spectrophotometrically in the extract using l,2(pyridyl azo)-2-naphthol. Using the same extraction system these workers were able to improve the detection limit of the method to 5 pg/1 (as linear alkyl sulfonic acid) in fresh estuarine and seawater samples. 

From an analytical point of view, the use of anionic surfactants as enhancers of CL reactions is most limited. One of the most recent examples is the use of sodium dodecylbenzene sulfonate (SDBS) as a CL enhancer of the system Ru(hpy) - SO - KBr03 (bpy = 2,2 -bipyridyl) [60], The authors of this work propose the following mechanism for the chemiluminescent system ... 

In abroad sense, the model developed for the cobaloxime(II)-catalyzed reactions seems to be valid also for the autoxidation of the alkyl mercaptan to disulfides in the presence of cobalt(II) phthalocyanine tetra-sodium sulfonate in reverse micelles (142). It was assumed that the rate-determining electron transfer within the catalyst-substrate-dioxygen complex leads to the formation of the final products via the RS and O - radicals. The yield of the disulfide product was higher in water-oil microemulsions prepared from a cationic surfactant than in the presence of an anionic surfactant. This difference is probably due to the stabilization of the monomeric form of the catalyst in the former environment. 

---