Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: missk15 on February 02, 2010, 03:14:55 PM
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Hello everyone,
Okay so I am working on one of the practice questions and I have come across a problem. There is a benzene ring and it is substituted at one position with a 3 fused rings. THe middle fused ring is also a benzene but the other two are simply hexenes (sharing one double bond with benzene ring).. I have performed a friedel's craft reaction on this compound,, and i think the product should be alkyl-added onto the para position in the original benzene ring (or could it also be that alkyl group can go to the other benzene ring). Then the next part involves reacting it with excess NBS in CCl4 and BPO. Now i cant figure out if the NBS can brominate all the benzylic carbons (which means 5 bromines on the subsituted ring structure) and one on the alkyl we added with freidal's craft. Its bothering me that its in excess plus why would NBS purposely wont pick the substituted ring benzene :( I hope I'm making sense explaning it.. Thanks
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Okay i will simplify the question..
IF there are more than 1 benzylic carbons present in a compound, when we are treating it with excess NBS/BPO/CCl4, would all the benzylic carbons would get brominated? Or is there any preference for one over the other?
Thanks
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If all of them are equivalent, they will have an equal probability of being attacked. So, the problem will simply boil down to the amount of reagent you are using.
On the contrary, if each benzylic carbon produces a different reactive intermediate (free radical/carbocation/carbanion), then you also need to take into account its stability.
Please correct me if I am wrong