Sciencemadness Discussion Board

Benzene reagents

Julie - 4-4-2006 at 19:37

Will benzene react with Cl2 or FeCl3 when heat is applied? Or does it react with Br2 and CCl4? Thanks xoxo

BromicAcid - 4-4-2006 at 20:35

I notice that you ask if it will react with Cl<sub>2</sub> <i>or</i> FeCl<sub>3</sub> and to be honest I'm not sure to what extent benzene will react with chlorine just under the influence of heat without ferric chloride. I don't think anhydrous ferric chloride will react with benzene on its own either. For the second half, I don't know about that, is the CCl<sub>4</sub>/Br<sub>2</sub> system some known organic system for preforming halogenation reactions? I'm not trying to be sarcastic here, I just don't know about these things and strange things can happen in chemistry, it seems to me there would be no reaction in this case but I could be wrong. Anyway, just trying to answer your questions exactly as they were asked, feel free to revise your question if you didn't get the answer you were expecting.

blazter - 5-4-2006 at 04:49

In order to chlorinate benzene, you would need both Cl2 and FeCl3. Just as with a bromination, the halide forms a complex with the FeX3, making in this case [FeCl3]-Cl which is stronly electrophilic. This complex is then electrophilic enough to add onto the benzene ring, displacing a hydrogen. Just about any organic textbook worth anything should explain this, and show the intermediate steps.

DrP - 5-4-2006 at 05:29

Quote:

is the CCl4/Br2 system some known organic system for preforming halogenation reactions?


I've used CCl4 and heat to chlorinate polymers - these were styrene / methyl styrene types so a benzene ring is involved. Sorry though - i'm not sure about plain benzene.

[Edited on 6-4-2006 by DrP]