Use of curly arrows to show bond-breaking
Pathways (mechanisms) for organic reactions involve both bond-breaking and bond-making. It is convenient to use curly arrows to show electron movement.
The cleavage of bond A–B below is referred to as heterolytic because one of the products has both electrons of the original bonding pair.
→ A+ + :B–
The cleavage of bond A–B below is referred to as homolytic because each product has one electron of the original bonding pair.
→ A· + ·B
The cleavage of bond A–B below is referred to as heterolytic because one of the products has both electrons of the original bonding pair.
→ A+ + :B–A curly arrow is used to signify movement of an electron pair from an atom or bond at the tail of the arrow towards an atom or bond at the head of the arrow. In the products of the electron movement above
A is positive (A+) due to owning one fewer electrons than in A-B where it was uncharged.
B is negative (B–) due to B owning one more electron than in A-B where it had no charge.
the overall charge is the same as the overall charge on reactants.
B is negative (B–) due to B owning one more electron than in A-B where it had no charge.
the overall charge is the same as the overall charge on reactants.
The cleavage of bond A–B below is referred to as homolytic because each product has one electron of the original bonding pair.
→ A· + ·BFishhooks (a curly arrow with a single prong at its head) signify the movement of a single electron from the atom or bond at the tail of the arrow to the atom at the head of the arrow.
The products are not charged because each owns the same number of electrons as they did in A–B.
Species with unpaired electrons such as A· are referred to as radicals.
The products are not charged because each owns the same number of electrons as they did in A–B.
Species with unpaired electrons such as A· are referred to as radicals.