A series of allyl aryl sulfides has been shown to isomerize readily on treatment with base to the corresponding propenyl aryl sulfides. The structures have been established in most cases by catalytic reduction of both isomers to the n-propyl aryl sulfides, as well as by consideration of the infrared and ultraviolet spectra. The compounds studied are the allyl derivatives of thiodicylic and 3, 5-dichlorothiosalicylic acids, allyl 2-pyridyl sulfide and allyl ...