Among the central reserach topics at Institute of Chemistry, University of Tartu is design and acidity measurements of superstrong acids – so-called superacids. Superacid is an acid that is more acidic than sulfuric acid (H2SO4), which is usually considered an epitome of a strong acid. Superacids and their derivatives already now have numerous applications in chemical technology and materials science. Just a couple of examples: a large share of the gasoline sold routinely at gasoline stations has been produced by processing with superacidic catalysts; salts of superacids are used in all Lithium ion batteries. Therefore it is fair to say that almost everyone of us daily uses items or materials that are in some way related to superacids. For their successful usage measurements of their strength are very important. Measuring the acid strength of a superacid is not easy.

The current status of this research at University of Tartu was summarized by an invited presentation on 20.01.2011 at Ludwig Maximilian University of Munich in a seminar specifically devoted to this topic. The image on the top left shows some of the strongest superacids ever envisaged by the humankind together with their predicted acidities in the gas phase. The image on the right displays the most acidic superacidity scale ever measured in a constant composition medium (See the original publication J. Org. Chem. 2011, 76, 391-395 for more details). This scale – built in 1,2-dichloroethane – lists the well-known mineral acids (sulfuric acid, hydrochloric acid, trifluoromethanesulfonic acid, perchloric acid, etc) as well as specifically designed superstrong acids (e.g. representatives of the cyanocarbon superacid family and trisulfonylmethane superacid family) and allows comparing their acidities (the stronger is the superacid, the lower it is positioned on the acidity scale).

For more information, please see the full presentation given at the seminar and the acid-base chemistry page at University of Tartu.

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