Alkylbenzene sulfonate alkyl-benzene

Alkylation of benzene using alpha olefins produces linear alkylbenzenes, which are further sulfonated and neutralized to linear alkylbenzene sulfonates (LABS). These compounds constitute, with alcohol ethoxy-sulfates and ethoxylates, the basic active ingredients for household detergents. Production of LABS is discussed in Chapter 10. 

Herlem et al463 have observed that asphaltene is dissolved in fluorosulfuric acid and the process is accompanied by strong redox reactions (SO2 and HF evolution). The products are mainly functionalized by SO3H groups, but SO2F groups were also detected by XPS. Indeed, model studies with benzene showed the formation of benzenesulfonic acid, diphenylsulfone, and benzenesulfonyl fluoride. For alkylbenzenes, sulfonation was not accompanied by cracking of the alkyl chain. 

Alkylbenzene sulfonates (R-C6H5-S03Na) are important surfactant compounds used in laundry detergents. Alkylbenzenes (made by the Friedel-Crafts alkylation of benzene using linear olefin molecules that have about twelve carbon atoms) are sulfonated, and the sulfonic acids are then neutralized with NaOH. 

The production of LAB involves the liquid-phase alkylation of benzene with linear monoolefins or alkyl chlorides. Liquid HF is used as catalyst for linear monoolefins. And the A1C13 is used as the catalyst for alkyl chlorides. Nowadays, acidic zeolite catalyst is used for olefin alkylation which generates less waste and reduces manufacture cost. The alkylate is then sulfonated to produce linear alkylbenzene sulfonate for biodegradable detergents. The manufacture of detergents is described in detail in Chapter 27. 

Perhaps the most widely used detergents are sodium salts of alkylbenzene-sulfonic acids. A long-chain alkyl group is attached to a benzene ring by the action... 

The synthetic detergents industry originated in the 1940s, when it was found that a new anionic surfactant type—alkylbenzene sulfonate—had detergent characteristics superior to those of natural soaps. The first surfactant of this kind was sodium dodecylbenzene sulfonate (SDBS). This material was produced by the Friedel-Crafts alkylation reaction of benzene with propylene tetramer (a mixture of Co olefin isomers), followed by sulfonation with oleum or sulfur trioxide and then neutralization, usually with sodium hydroxide. The alkylation was typically performed using homogenous acid catalysts, such as HF or sulfuric acid. 

A wide use of synthetic detergents (SD) began in the forties of the 20" century, after mastering the commercial production of anionics (alkyl sulfonates - Germany alkylbenzene sulfonates -USA, United Kingdom) and nonionics (ethoxylated alkyl benzenes - Germany). 

See TEA alkylbenzene sulfonate Alkylbenzenesulfonic acid. See Dodecylbenzenesulfonic acid Alkylbenzol CIO-13 distillation residues. See Benzene, mono-CI0-13-alkyl derive., distillation residues... 

Benzenesulfonic acid butyl amide. See N,N-Butyl benzene sulfonamide Benzenesulfonic acid, C10-16-alkyl derivs., compds. with triethanolamine. See TEA alkylbenzene sulfonate Benzenesulfonic acid, 3,3 -carbonylbis (4-hydroxy-6-methoxy-, disodium salt. See Benzophenone-9... 

The anionic surface-active compounds with the largest volume of production are the alkylbenzene sulfonates. Here, the possibility of an easy insertion of a sulfonic acid group into the benzene molecule is used to obtain inexpensive surfactants. Suitable starting materials are alkylbenzenes with an alkyl chain length of ca. 12 carbon atoms, obtained by the application of olefines or monochloroalkanes to the benzene ring. 

In the alkylbenzene sulfonates, with various points of attachment of the alkyl group to the benzene ring, experimental data indicate that the aromatic ring has substantial hydrophilic character, with the benzene ring contribution being equivalent to about 3.5 carbon atoms. 

Modem benzene-based surfactants have alkyl groups with 10 to 14 carbon atoms, since with fewer than 6 carbon atoms in the alkyl group the alkylbenzene sulfonates are not sufficiently surface active, and alkylbenzene sulfonates with 15 and more carbon atoms in the alkyl group are difficult to dissolve in water, although they are soluble in organic media. 

The dilemma in discussing environmental acceptability of petroleum sulfonates is (1) the dearth of environmental data on this class and (2) the diversity of chemical structures which makes biodegradation and toxicity information difficult to interpret. A logical approach is to look at the environmental properties of a prototypical structure that represents petroleum sulfonates, This structure would be an alkyl aryl sulfonate, and the best candidate is linear alkylbenzene sulfonate. Linear alkyl-benzene sulfonate (LAS) has been the focus of more environmental studies than any other surfactant, and it is a good surrogate for understanding the fate and effects of alkyl aryl sulfonates and petroleum sulfonates. 

Representative Electrophilic Aromatic Substitution Reactions of Benzene 457 Mechanistic Principles of Electrophilic Aromatic Substitution 458 Nitration of Benzene 459 Sulfonation of Benzene 461 Halogenation of Benzene 462 Biosynthetic Halogenation 464 Friedel-Crafts Alkylation of Benzene Friedel-Crafts Acylation of Benzene Synthesis of Alkylbenzenes by Acylation-Reduction 469 Rate and Regioselectivity in Electrophilic Aromatic Substitution 470 Rate and Regioselectivity in the Nitration ofToluene 472... 

Similar results were reported by Lundgren and coworkers for alkyl-benzene sulfonate mixtures, the type formula of which is also given in Fig. 1. For sodium alkylbenzene sulfonate, D = 11.4 X 10 cm.Vsec. (83), and the micellar weight calculated upon the assumption of spherical particles is approximately 15,000. Lundgren, Elam, and O Connell (82) assert that variation in the concentration of the detergent from 0.25 to 1.5% results in no detectable difference in electrophoretic behavior. Viscosity measurements (81, 83) reveal that the micelles are not highly asymmetric in dilute solution. 

The second source of sulfonic acid uses the following reaction scheme alkylation of benzene by a propylene oligomer then sulfonation of the alkylbenzene. 

The acidity of perfluorinated sulfonic acids can be increased further by complexa-tion with Lewis acid fluorides, such as SbF5, TaF5, and NbF5.183 They have been found to be effective catalysts for n-hexane, n-heptane isomerization, alkylation of benzene, and transalkylation of alkylbenzenes (see Chapter 5). 

Two of the reactions that are used in the industrial preparation of detergents are electrophilic aromatic substitution reactions. First, a large hydrocarbon group is attached to a benzene ring by a Friedel-Crafts alkylation reaction employing tetrapropene as the source of the carbocation electrophile. The resulting alkylbenzene is then sulfonated by reaction with sulfuric acid. Deprotonation of the sulfonic acid with sodium hydroxide produces the detergent. 

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