Switchable solvents are a unique class of solvents that were developed to facilitate both reaction and subsequent product separation. Their “built-in” separation ability for facile product recovery is paramount to achieving chemical processes that are both economically competitive and environmentally conscious. Two classes of switchable solvents are discussed: 1) piperylene sulfone—a volatile and recycle DMSO substitute and 2) one and two-component reversible ionic liquids—solvent systems that can be switched back and forth between molecular liquids and ionic liquids.