, a concerted reaction
is a chemical reaction
in which all bond breaking and bond making occurs in a single step. Reactive intermediates
or other unstable high energy intermediates are not involved. Concerted reaction rates
tend not to depend on solvent polarity
ruling out large buildup of charge
in the transition state
reactions are concerted reactions.
In the SN2 reaction a concerted reaction also takes place. Because the reaction rate is bimolecular there are two molecular species controlling the rate of the reaction. Because the rate is dependent on two molecules the reaction does not have any intermediate steps, only a transition state. This means that all the bond making and bond breaking takes place in a single step. In order for the reaction to occur both molecules must be situated correctly. Therefore, the reaction is said to be concerted because it occurs in one step.
- Carey, Francis A.; Sundberg, Richard J.; (1984). Advanced Organic Chemistry Part A Structure and Mechanisms (2nd ed.). New York N.Y.: Plenum Press. ISBN 0-306-41198-9.