Keynote Lecture
Quantification of Polar Organic Reactivity

The precision of quantum chemical calculations has reached a level that they can predict the thermodynamics of organic reactions in the gas phase with an accuracy sometimes even exceeding that of experimental methods. In contrast, calculations of reaction pathways in solution are still rather laborious and are predominantly used for investigating mechanisms of known reactions rather than for designing new synthetic transformations. For the latter purpose, linear free energy relationships are still indispensable tools. Thus, pK_a values¹ are often used for estimating relative nucleophilic reactivities and leaving group abilities (nucleofugalities) of certain species. A limitation of these so-called Brønsted correlations is the fact that pK_a values refer to interactions with the proton, while most reactions considered involve formation or cleavage of bonds to carbon. We have, therefore, developed a Lewis basicity scale² with respect to C-centered Lewis acids (carbocations and electron-poor p-systems) and discuss their correlations with nucleophilicities³ and nucleofugalities. Analogous relationships between Lewis acidities, electrophilicities, and electrofugalities will also be reported.⁴

1) For a comprehensive collection of pK_a values see: http://ibond.nankai.edu.cn/.

2) Mayr, H.; Ammer, J.; Baidya, M.; Maji, B.; Nigst, T. A.; Ofial, A. R.; Singer, T. Am. Chem. Soc.
2015, 137, 2580−2599.

3) For a collection of nucleophilicity and electrophilicity parameters see:
http://www.cup.lmu.de/oc/mayr/DBintro.html

4) Mayr, H.; Ofial, A. R. Chem. Res. 2016, 49, 952–965.