"Chemometrics" applied to the optimization of the preparation of hydrotropes for detergents starting from BTX fraction of natural gas

Manufacturers of cleaning products use hydrotropes to increase the solubili ty of surfactants in concentrated liquid detergents, In contrast to benzene sulfonate, alkylbenzenesulonates with short chains (n < 4) are used as hydr otropes, In this paper, we present the results obtained from the preparatio n of toluenesulfonic and xylenesulfonic acids by selective sulfonation of t oluene and xylenes present in the BTX fraction (benzene, toluene, xylenes) of the Tunisian natural gas MISKAR deposit. Chemometrics were applied to de termine the optimal experimental conditions for the selective sulfonation o f toluene and xylenes, we use a 2(IV)(6-2) fractional factorial design in a ddition to several analytical methods (GC, HPLC, FTIR...), These conditions found to be: the use of concentrated sulfuric acid as sulfonating agent, t he azeotropic elimination of water during the reaction, a temperature of 11 0 degreesC, a duration of 9 hours and a molar ratio of sulfuric acid to tol uene plus xylenes of 0.8. The application of all of these experimental cond itions gives an aqueous phase with a composition that can be used very effe ctively as hydrotrope agent in liquid detergents. This conclusion was the o utcome from comparing the effect of our product on the clear point of a typ ical premium formulation of a liquid detergent to of sodium xylenesulfonate s, the most important hydrotope for light duty liquids.