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A pH Scale for the Protic Ionic Liquid Ethylammonium Nitrate
Author(s) -
Kanzaki Ryo,
Kodamatani Hitoshi,
Tomiyasu Takashi,
Watanabe Hikari,
Umebayashi Yasuhiro
Publication year - 2016
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201511328
Subject(s) - ionic liquid , chemistry , potentiometric titration , solvation , nitrate , titration , inorganic chemistry , base (topology) , ion , organic chemistry , catalysis , mathematical analysis , mathematics
To quantify the properties of protic ionic liquids (PILs) as acid–base reaction media, potentiometric titrations were carried out in a neat PIL, ethylammonium nitrate (EAN). A linear relationship was found between the 14 p K a values of 12 compounds in EAN and in water. In other words, the p K a value in EAN was found to be roughly one unit greater than that in water regardless of the charge and hydrophobicity of the compounds. It is possible that this could be explained by the stronger acidity of HNO 3 in EAN than that of H 3 O + in water and not by the difference in the solvation state of the ions. The pH value in EAN ranges from −1 to 9 on the pH scale based on the pH value in water.