Synthetic studies have been conducted on di- and trisulfonates of diphenylalkanes which may be the enhanced oil recovery (EOR) agents in commercial alkylbenzenesulfonates. Nine di- and trisulfonates of diphenylalkanes have been made and none has much EOR activity as the active fractions of commercial alkylbenzenesulfonates. Texas 2 (sulfonate of 5-(p-ethylphenyl) dodecane) has good EOR activity but Texas 2 has low solubility in brine. Structure modifications of Texas 2 led to compounds with less EOR activity than Texas 2 has. Removal of the para ethyl group from Texas gave a compound with no EOR activity as did the shortening of the longer alkyl group from 12 to 8 carbons. Replacing the ethyl group of Texas 2 with hydroxy and subsequent sulfonation yielded a sparingly brine soluble product with low EOR activity. Preliminary infrared and nuclear magnetic resonance studies of the methyl esters of EOR activity fractions of commercial alkylbenzenesulfonates (NBS and N5B) indicate that the active fractions are mixtures of p-alkylbenzenesulfonates.