Dodecylbenzene, sulfur trioxide

Exothermic Gas Absorption with Complex Reaction Sulfonation and Discoloration in the Absorption of Sulfur Trioxide in Dodecylbenzene... 

Mann and Moyes111 developed an approximate film theory to describe gas absorption and interfacial temperature behavior under very exothermic conditions. They used the theory to analyze their own experimental data for the sulfur trioxide dodecylbenzene system. They showed (both experimentally as well as theoretically) that in a highly exothermic reaction system the chemical absorption rate could be lower than the physical absorption rate because the depression of interfacial solubility can greatly reduce the absorption potential under reacting conditions. 

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. 

The dodecylbenzene mixtures are sulfonated with sulfur trioxide or air or oleum (sulfur trioxide in sulfuric acid) to produce the dodecylbenzenesulfonic acid products. Dodecylbenzenesulfonic acid is sold in concentrated form. Other single or multiple alkylated benzene or naphthalene sulfonic acids are similarly manufactured. 

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