In: Chemistry
What are the relative pKas of strong electrophiles vs. strong nucleophiles? Please explain the difference between electrophiles and nucleophiles.
A nucleophile provides a pair of electrons to form a new covalent bond. It can be also seen as a Broensted base. Stronger the base (higher pKa for the acid/base couple), stronger the nucleophile, e.g. this series of nucleophilicity –NH2 > HO- > F-, but it not true for this series Cl- > F- or HS- > HO-.
In an acid/base couple, the base is always a stronger nucleophile.
For strong bases/nucleophiles, pKa>14.
An electrophile accepts a pair of electrons to form a new covalent bond. It can’t be identified as Broensted acid or base.