It depends on what reaction you're doing. Some reactions require specific solvents, others require the absence of certain solvents.
Grignard reactions, for example, require the presence of an ether to form the organomagnesium halide. You can replace diethyl ether with THF or
glyme, but not toluene or dichloromethane. Once you've made the RMgX, you can have toluene or benzene in the solvent mixture, but not an ester,
ketone, or alcohol.
If you're extracting something organic from aqueous solution, dichloromethane will generally work just as well, but alcohol or acetone won't (because
it mixes with the water). Toluene might work, but then it's hard to boil off the solvent to get your extract out. Ethyl acetate would work, unless
the aqueous solution is acidic or basic enough to hydrolyze the ester.
Hydrocarbons are generally interchangeable, unless the boiling points are a problem (if the reaction calls for refluxing the reaction in toluene,
using pentane instead won't get you anywhere. If you want your solvent to boil off easily, decalin isn't a good choice). Photolysis with UV will
work in an alkane solvent, but aromatics are opaque to UV.
Light alkanes such as pentane and hexane are crappy solvents, and often good antisolvents, for most mildly polar solutes.
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