In organic chemistry, an electrophilic addition reaction is an addition reaction where in chemical compound a pi bond is removed by the creation of two new covalent bonds. In electrophilic additions common substrates have a carbon-carbon double bond or triple bond.
Y-Z + C=C → Y-C-C-Z
The driving force for this reaction is the formation of an electrophile Y+ that forms a covalent bond with a electron-rich unsaturated system (-C=C-) (step 1). The positive charge on Y is transferred to the carbon - carbon bond.
step (1) Y+ + -C=C- → Y-C-C+-
In step 2 of an electrophilic addition the positively charged intermediate combines with (Z) that is electron-rich to form the second covalent bond.
step (2) Y-C-C+- + Z → Y-C-C-Z
Step 2 is also found in a SN1 reaction. The exact nature of the electrophile and the nature of the positively charged intermediate is not always clear and depends on reactants and reaction conditions.
Typical reactions are:
In all asymmetric addition reactions to carbon regioselectivity is important and often determined by Markovnikov's rule.
