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Chemistry help on benzene

Ok so I’m just wondering -
When benzene undergoes electrophilic substitution, how many pi electrons does the intermediate have (the positively charged ring)
I cane across a question on this and it says 4. I’m confused as I thought it’d be 5?
Original post by starrynight01
Ok so I’m just wondering -
When benzene undergoes electrophilic substitution, how many pi electrons does the intermediate have (the positively charged ring)
I cane across a question on this and it says 4. I’m confused as I thought it’d be 5?

Hi,

If you think about it with the kekule structure in mind, its a bit easier to imagine:
A bezene molecule has 6 pi electrons. When an electrophile joins onto the benzene ring, one of the double carbon bond becomes a single carbon bond, meaning that you only have 2 double carbon bonds left. Since each double carbon bond contains 2 pi electrons, there must be only 4 pi electrons present in the intermediate.

Hope this helps :smile:
Reply 2
Original post by Biolover2020
Hi,

If you think about it with the kekule structure in mind, its a bit easier to imagine:
A bezene molecule has 6 pi electrons. When an electrophile joins onto the benzene ring, one of the double carbon bond becomes a single carbon bond, meaning that you only have 2 double carbon bonds left. Since each double carbon bond contains 2 pi electrons, there must be only 4 pi electrons present in the intermediate.

Hope this helps :smile:


Ah that makes it easier to understand, thank you! I kept imagining it only attaching to one carbon so only one electron is lost but it makes sense now because the electrophile is +vely charged. Thank again!! :smile:
Original post by starrynight01
Ah that makes it easier to understand, thank you! I kept imagining it only attaching to one carbon so only one electron is lost but it makes sense now because the electrophile is +vely charged. Thank again!! :smile:

no problem :smile:

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