A short history of ionic liquids—from molten salts to neoteric solvents

Ionic liquids, defined here as salts with melting temperatures below 100 °C, evolved from traditional high temperature molten salts. Some materials we would now recognize as ionic liquids were observed as far back as the mid 19th century. The quest for useful molten salts with lower melting temperatures led to inorganic chloroaluminates, to organic chloroaluminates, then to the water and air stable salts now being developed for green chemistry applications.