Extractive phase vanishing reactions with dichloromethane, perfluorohexanes, and dibromoethane: slow addition in a test tube.

[reaction: see text] Partition coefficient measurements and experiments with a dye show that a new fluorous "phase vanishing reaction" described by Jana and Verkade occurs by an extractive mechanism. This mechanism is contrasted with the original diffusive phase-vanishing reactions introduced by Ryu and co-workers.