The direct sulfonation of phenylalkanoic acids has been reported to result in nuclear sulfonation only. Phenylacetic acid has been sulfonated with concentrated sulfuric acid, chlorosulfonic acid3 and sulfur trioxide4 to give 0-and $-sulfophenylacetic acids. Analogous results have been obtained with p-phenylpropionic acid. 6 Recently, acetophenone has been sulfonated with dioxane sulfur trioxide to give w-acetophenonesulfonic acid in good ...
