Water and diethyl ether are not miscible due to the polarity of the two substances. Water is a very polar substance and diethyl ether is non-polar, therefore the two are immiscible when combined. (solubility: 6. 9 g/100ml) (dichloromethane: 1. 33 g/m3; water: ~1. 00 g/m3) Since water bas a lower density than dichloromethane, i would expect dichloromethane to be situated on the bottom of the vessel and water to be in the upper layer. An optimal solvent for recrystallization will dissolve little of the compound when the solvent is cold, but should dissolve all of the compound when hot. The solvent must not react with the desired compound. The impurities should be very soluble in the cold solvent, or insoluble in the hot solvent. Tlc is a useful lab technique because it is quick, relatively inexpensive and only requires a very little amount of the sample, but gives very useful preliminary results.