## α-effect

https://doi.org/10.1351/goldbook.A00006
A positive @D01650@ of an α-nucleophile (a nucleophile bearing an unshared pair of electrons on an atom adjacent to the nucleophilic site) from a Brønsted-type plot of $$\text{log}k_{\text{nuc}}$$ vs. $$\text{p}K_{\text{a}}$$ constructed for a series of related normal nucleophiles. More generally, it is the influence of the atom bearing a lone pair of electrons on the reactivity at the adjacent site.
Note:
The use of the term has been extended to include the effect of any substituent on an adjacent reactive centre, for example in the case of the 'α-silicon effect'.