ABSTRACT
Alkylbenzene sulfonates and alkylnaphthalene sulfonates act as hydrotropes to modify solubilities, viscosities, and other properties of surfactants and surfactant formulations. Sodium toluenesulfonate (STS) and sodium xylene sulfonate (SXS) are the best-known hydrotropes, however, alkylnaphthalene sulfonates also possess hydrotropic properties. Hydrotropicity is the amount of different hydrotropes required to achieve clear solutions. The amount of different hydrotropes, for example, SXS, STS, sodium cumene sulfonate (SCS), and others, in light-duty liquid (LDL) detergent formulations is given in Figure 14.1. There seems to be no trend; different hydrotropes are (more or less) similarly ef cient in different formulations.
