Sulfonation of alkylbenzene

Sulfonation of LAB. The sulfonation of alkylbenzenes leads to sulfonic acid tyre product, which is then neutralized with a base such as sodium hydroxide to produce sodium alkylbenzene sulfonate. The sulfonation reaction is highly exothermic and instantaneous. An efficient reactor heat removal system is used to prevent the decomposition of the resultant sulfonic acid. The sulfonation reaction takes place by using oleum (SO3H2SO4) or sulfur trioxide (SO3). Although, the oleum sulfonation requires relatively inexpensive equipment, the oleum process has major disadvantages compared to sulfur trioxide. The need for spent acid stream disposal and the potential corrosion owing to sulfuric acid generation increased the problems related to oleum process [1]. 

The gaseous air or SO3 sulfonation process leads to high yields of sulfonic acid (95 to 98 percent). This process comprises three major steps. The sulfonation of alkylbenzene with air or SO3 forms the alkylbenzene sulfonic acid and anhydride. The latter is decomposed into the alkylbenzene sulfonic acid by hydration. The neutralization of the sulfonic acid into the corresponding sodium salt represents the last chemical step in the process of formation of detergents [1]. 

Production of aikyibenzene suifonates [1, 2]. The alkylbenzene sulfonates, used as liquid surfactants in making the detergent slurry, are produced by the sulfonation of linear alkylates followed by the neutralization step with a caustic solution containing sodium hydroxide (NaOH). The process of sulfonation of alkylbenzenes with oleum takes... 

Sulfonation of alkylbenzene, 23-25 Sulfur dioxide, optimum temperature for oxidation of 8-9... 

Figure 5.38 shows the flow diagram for the sulfonation of alkylbenzene with sulfur trioxide. 

Today thin-film reactors are used not only for preparing ester sulfonates but for the sulfonation of alkylbenzenes or for the sulfonation of long-chain alcohols. The principle of this technique is that both reactants are fed to the equipment in a concurrent stream. Sulfur trioxide reacts with the organic component to form sulfonic acid, which continues through the reactor and is finally removed from the residual inert gas using a cyclone-type separator. 

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

Emulsion polymerization is widely used to produce polymers in the form of emulsions, such as paints and floor polishes. It also used to polymerize many water insoluble vinyl monomers, such as styrene and vinyl chloride. In emulsion polymerization, an agent emulsifies the monomers. Emulsifying agents should have a finite solubility. They are either ionic, as in the case of alkylbenzene sulfonates, or nonionic, like polyvinyl alcohol. 

The following section describes as an example the sulfonation of toluene to />-toluenesulfonic acid. Concerning the formation of byproducts, see page 81. Figure 24 gives an overview of the process [162]. The maunufacture of p-toluenesulfonic acid follows continuously by the conversion of alkylbenzene with 96-100% sulfuric acid in the mixing vessel Rl. The formed water is re-... 

Neutralization of the sulfonation product from a-olefins is more complex than neutralization of the corresponding products of alkylbenzenes. This is because the S03-a-olefin acid product contains about 50% free sulfonic acid, the rest being C(l,3) and D(l,4) sultones, assuming that with acid aging the 0(1,2) sultones have disappeared. In the case of a-olefins an excess of caustic (1.5-2.0% excess) must be added to neutralize both the sulfonic acid initially present and that formed on subsequent hydrolysis of the C(l,3) and D(l,4) sultones. The sultones (ring-structured esters) cannot be converted to their proper salts by a simple neutralization but need a hydrolysis step. 

The thermal degradation of alkylbenzene sulfonates in alkaline media is important because of the application at elevated temperatures. The half-lives, with respect to thermal degradation, of several commercially available sulfonates were estimated at hundreds to thousands of years at 204° C. The degradation mechanism was predominately a clipping of the alkyl chain to yield an alkylbenzene sulfonate with the phenyl group attached to the a-carbon however, desulfonation also occurred [1624]. 

R. D. Shupe and T. D. Baugh. Thermal stability and degradation mechanism of alkylbenzene sulfonates in alkaline media. J Colloid Interface Sci, 145(l) 235-254, August 1991. 

SPECTROMETRY—VII. ANIONIC SURFACTANTS LC-MS OF ALKYLBENZENE SULFONATES AND RELATED COMPOUNDS... 

The presence of some surfactants or their by-products in the aquatic environment has been considered as a potential marker of pollution [45, 325]. Thus, the presence of alkylbenzene sulfonates in groundwater has been used as an indicator of the age of the groundwater [358]. Linear alkylbenzenes can act as tracers of domestic waste in the marine environment [34,35,359,360] and trial-kylamines as indicators of urban sewage in sludge, coastal waters, and sediments [17,33,45,325, 327, 346,361]. Analysis, identification, and characterization of surfactants are extensively reviewed and discussed by Aboul-Kassim and Simoneit [314], while pollution problems associated with these compounds are reviewed by Aboul-Kassim and Simoneit [356]. 

Sulfonation of Benzene and Alkylbenzenes. Since the main utilization of ben-zenesulfonic acid was its transformation to phenol, the importance of the sulfonation of benzene has diminished. The process, however, is still occasionally utilized since it is a simple and economical procedure even on a small scale. Excess sulfuric acid or oleum is used at 110-150°C to produce benzenesulfonic acid.97,102 Sulfonation of toluene under similar conditions yields a mixture of isomeric toluenesul-fonic acids rich in the para isomer. This mixture is transformed directly to cresols by alkali fusion. 

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). 

Studying the formylation of alkylbenzenes in HS03F-SbF5, Tanaka et al436 have observed both formylation and sulfonation. However, in the presence of HSO3F, that is at low acidity level, only sulfonyl compounds were obtained [Eq. (5.167)], whereas increasing acidity (with added SbF5) resulted in the formation of products of formylation. 

The high nonionic formulation gives better performance with sebum soils, whereas excellent performance on certain oily soils can be obtained through the use of alkylbenzene sulfonates at the high sulfonate to nonionic ratio. 

Sulfonation is economically important because alkylbenzene sulfonates are widely used as detergents. Sulfonation of an alkylbenzene (R = unbranched C10-C14) gives an alkylbenzenesulfonic acid, which is neutralized with base to give an alkylbenzene sulfonate detergent. Detergents are covered in more detail in Section 25-4. 

Alkylbenzene. Alkylbenzene is an intermediate for the production of alkylbenzene sulfonate. Alkylbenzene consists of a mixture of phenyl substituted n-alkanes of 9 to 14 carbon atoms. Prior to 1965, alkylbenzene was synthesized from propylene tetramer, obtained by oligomerization of propylene. The resulting hard alkylate was a highly branched chain compound. However, the slow biodegradability of propylene tetramer-based materials soon became apparent and by 1965, most of the detergent industry had switched over to linear alkylbenzene. Extensive research has demonstrated... 

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