Abstract: A solvent that reversibly converts from a nonionic liquid mixture to an ionic liquid upon contact with a selected trigger, e.g., contact with CO2, is described. In preferred embodiments, the ionic solvent is readily converted back to the nonionic liquid mixture. The nonionic liquid mixture includes an amidine or guanidine or both, and water, alcohol, or a combination thereof. Single component amine solvents that reversibly convert between ionic and non-ionic states are also described. Some embodiments require increased pressure to convert; others convert at 1 atmosphere.

Abstract: Combinations of catalyst and compound are described that are suitable for use in a thermally regenerative fuel cell. Such combinations offer greater than 99% selectivity and accordingly they cycle through a reversible dehydrogenation process with substantially no loss due to byproduct formation. Combinations of secondary benzylic alcohols and Pd/SiO2 catalysts offer levels of by-products that are undetectable by NMR and GC analysis. With such TRFC, thermal energy can be converted into electric energy in a moving vehicle without the requirement of storage of H2, and its safety issues. Instead, a catalytic amount of H2 is cycled through the system and used to generate electric energy.

Abstract: A solvent that reversibly converts from a hydrophobic liquid form to hydrophilic liquid form upon contact with water and a selected trigger, e.g., contact with CO2, is described. The hydrophilic liquid form is readily converted back to the hydrophobic liquid form and water. The hydrophobic liquid is an amidine or amine. The hydrophilic liquid form comprises an amidinium salt or an ammonium salt.

Abstract: A solvent that reversibly converts from a nonionic liquid mixture to an ionic liquid upon contact with a selected trigger, e.g., contact with CO2, is described. In preferred embodiments, the ionic solvent is readily converted back to the nonionic liquid mixture. The nonionic liquid mixture includes an amidine or guanidine or both, and water, alcohol, or a combination thereof. Single component amine solvents that reversibly convert between ionic and non-ionic states are also described. Some embodiments require increased pressure to convert; others convert at 1 atmosphere.

Abstract: Reversibly switchable negatively charged surfactants are provided. The anionic surfactant is formed in aqueous solution by providing an absence of CO2 and is converted to a non-surfactant neutral state through exposure to CO2. The anionic switchable surfactants are useful to stabilize emulsions. In the neutral state they are useful to separate immiscible liquids. The surfactants find uses in polymerization, the oil industry, remediation of oil-contaminated soil and recapture of oil contaminant, and formation of solid particles such as plastics and nanoparticles.

Abstract: Reversible switchable surfactants are provided. A surfactant is the salt of an amidine or guanidine having at least one R group that is a hydrophobic moiety selected from the group consisting of higher aliphatic moiety, higher siloxyl moiety, higher aliphatic/siloxyl moiety, aliphatic/aryl moiety, siloxyl/aryl moiety, and aliphatic/siloxyl/aryl moiety. The other R groups are smaller moieties such as H, C1 to C4 aliphatic or the like. The surfactant is turned on by a gas that liberates hydrogen ions, such as, for example, carbon dioxide, which liberates hydrogen ions in the presence of water. The surfactant is turned off by exposure to a flushing gas and/or heating. When “on” the surfactants are useful to stabilize emulsions, and when “off” they are useful to separate immiscible liquids or a liquid and a solid. The surfactants find uses in polymerization and in the oil industry.

Abstract: Methods of enhancing the solubility of a fluorinated compound in an organic solvent are provided. In one embodiment, carbon dioxide gas pressure is applied to the solvent at a pressure effective to enhance the solubility of the fluorinated compound. The method may further include recrystallizing the fluorinated compound by reducing the pressure of the carbon dioxide gas. Also provided are methods of conducting a reaction using a fluorinated compound in an organic solvent. In one embodiment, the method comprises applying carbon dioxide pressure to an organic solvent comprising at least one substrate and a fluorinated catalyst, in an effective amount to solubilize the catalyst; and permitting the fluorinated catalyst to catalyze the reaction of the substrate to form a product. The catalyst is optionally separated from the reaction product and solvent after the reaction by the release of the pressure.