distillation process where the distillate is the desired product it is conventional to control the column at a point near to the point that distillate is withdrawn from the column in the instant process the product draw off of purified acetone is of course grossly ratioed to the feed rate of crude acetone however for precise control of the temperature profile of the column the product draw off is adjusted to maintain a constant preselected temperature on a tray or plate in the region between the caustic feed point and the crude acetone feed points it will be understood that the preselected temperature is dependent on the pressure in the column at that tray and thus the preselected pressure compensated temperature is an indication of the composition profile at that point with the 60 tray column being utilized it has been found that there is sensitive interaction between the water and acetone profiles around the tenth tray and the product draw off rate steam input at 2 is ratioed to the vapor and liquid feeds in accordance with the relative amounts of vapor and liquid flows the product draw off at 8 is ratioed to the feed rates with the ratio adjusted by the pressure compensated temperature on the tenth tray in this manner essentially only acetone is in the overhead and the cumene can be forced to the bottom with water spent caustic and the aldol condensation products the process of the instant invention has resulted in the elimination of the oil sidedraw necessary in the previously discussed u s pat no 3 668 256 process this has contributed significantly to the simplification of.