Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: anything.john on May 07, 2008, 10:15:09 AM
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Why is methylbenzene more susceptible to an electrophilic attack than benzene?
What effect does the methyl group have on the electrons?
Is there a dipole effect?
Also,
Why is the 2-position on the methylbenzene ring attacked by electrophiles more readily than the 3-position? What effect does the methyl group has on this?
Thanks in advance :)
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This thread should have all the information you need. There are some links included in there as well.
http://www.chemicalforums.com/index.php?topic=26152.0
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methylbenzene (toluene) is more susceptible to electrophilic attack because the methyl group is an activating group and therefore makes the ring more electron rich, making it more desirable for electrophiles. activating groups also direct orth-para because the resonance structures of the cationic intermediate is more stable. I havent written them out in a while but i believe it is because the positive charge can be placed next to the methyl group, stabilizing it which means the intermediate will be lower in energy than if the electrophile were to be placed at the meta position.
it might be a good idea to draw all of the resonance structures of the intermediate after electrophilic attack but before restoration of aromaticity. place the electrophile at all three positions and see where the postive charge is most stable.
hope this helps
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it might be a good idea to draw all of the resonance structures of the intermediate after electrophilic attack but before restoration of aromaticity. place the electrophile at all three positions and see where the postive charge is most stable.
What he said.
Remember that you can also draw resonance for structures for hyperconjugation, for example:
(https://www.chemicalforums.com/proxy.php?request=http%3A%2F%2Fi28.tinypic.com%2Fizwz28.jpg&hash=bf199091970ac658b9aa3b4b132b249aef42c3a3)