why chlorobenzene and benzene do not react in friedel kraft?

Question

australopithecus · Answer

Essentially Benzene Carbon halogen bonds are stronger than regular carbon hydrogen bonds. Which likely makes the chlorines ability to act as a leaving group even after bond polerization by the lewis acid catalyst impossible under normal conditions. Although, they have performed this reaction with the inclusion of catalyists to make the reaction more favorable. I was going to write what was below but I felt like they did a better job on this site: "Carbon halogen bond is stronger in haloarene compare to haloalkanes due to resonance in haloarene, which impart partial double bond character to carbon halogen bond. Hence Carbon-halogen bond length is lesser in haloarene compare to haloalkane." http://chemistry.tutorvista.com/organic-chemistry/aryl-halide.html