What is the difference between a Lewis acid (base) and a nucleophile (electrophile)?
The essential difference is that the acidity/basicity is a thermodynamical
property, measured with the equilibrium constant
, while the electrophilicity/nucleophilicity is a cinetic property
, measured with the kinetic constant
. So, a strong lewis acid, for ex., can react slowly with a lewis base and so be a weak electrophile; or a strong electrophile, which reacts fast with a nucleophile, can have a low equilibrium constant and so be a weak lewis acid. Usually a strong lewis acid/base is also a strong electrophile/nucleophile, but it's not always so, for the reason I've written.