I want to know that why a carboxylic not form two layer with diluent and extractant in reactive extractant process for studying kinetic parameters. It forms double layer in equilibrium study but not in kinetic study.
TBP is miscible with diethyl ether, benzene, CS2 and not soluble in water. Thus, I would not be surprise if it is miscible with heptane also. You can check easily if TBP and heptane are indeed miscible. If yes, try to find alternative for either diluent or extractant. For sure, your choice should depend on the question you want to answer and the reason you need those kinetic parameters in the first place.