Why is diethyl ether used to extract an organic product from water at the end of a reaction?

The normal boiling point of diethyl ether is #34.6# #""^@C#; that of water's you know...............Typically at the end of a reaction, we dump in water to #"quench"# the reaction, i.e. to stop it cooking. The product is #"partitioned"# between the 2 phases: the organic product passes into the ethereal phase, and the inorganic byproducts are retained by the aqueous phase, so this is a good preliminary separation step.

Now ether is quite a volatile solvent. If it is placed under suction (i.e. on a rotary evaporator), you can strip all the ether off quite rapidly. You are left with the crude product, which can be recrystallized or distilled.

Had you tried to strip off water, you would be there for hours........Moreover, most organic materials have quite good solubility in ether solution. Once in the separating funnel, the organic phase can be #"washed"# with other reagents, i.e. acids, brines, to purify the product. Of course, you must also dry the organic phase.........but this is easily accomplished with anhydrous magnesium sulfate or something similar.