On the nature of Parr functions to predict the most reactive sites along organic polar reactions

- The meaning of the empirically defined “Parr functions” (PF) descriptors is clarified.
- PF measure local electrophilic and local nucleophilic propensities.
- PF have been successfully applied to describe polar organic reactions.
- [Nα, Nβ] SP-DFT Fukui indices are associated to PF.