Rapid method for determination of unsulfonated oils

A primary limitation to alkylbenzene sulfonation processes has been the lack of a rapid method to sense the quality of sulfonation. This is especially true for a process using sulfur trioxide where both the level of sulfonating agent and time are critical: too little reagent results in high oils; too much reagent degrades product color; and a delay in the process also degrades color. Although steam distillation of oils from the neutralized sulfonate can be conducted in about one and one-half hours for commercial dodecylbenzene derivatives, far greater time is required for higher molecular weight homologs. Extraction of oils requires about one hour and more operator time than distillation. The use of ethylene glycol as the principal carrier solvent, along with a small amount of water, provides oil values within 10 min distillation time. It is also applicable to longer chain alkylbenzene. sulfonates besides those from dodecylbenzene. Subsequently, extracted oils are high, ca. 90%, in sulfone content. Glycol distilled oils plus subsequently extracted oils (sulfones) are slightly greater than oils obtained exclusively by extraction. It has been realized that some of the more volatile oils are lost during the usual extraction procedure. The glycol oils distillation method has been successfully used in plants for alkylbenzene sulfonic acid quality control.