Liquids that consist of a mixture of an alcohol and either an amidine or a guanidine have been developed to switch from a low-polarity form to a high-polarity ionic liquid upon treatment with CO2 at atmospheric pressure. Treatment with N-2 and/or mild heat (50-60 degrees C) reverses the process. These liquids can be used as switchable solvents to dissolve and then precipitate a solute or to dissolve reagents for a chemical synthesis and then precipitate the product.