mechanism : electrophilic substitution of Benzene

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JanaALEVEL
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How do I know where to put the circled x here ?
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charco
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(Original post by JanaALEVEL)
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How do I know where to put the circled x here ?
Which circled X?
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JanaALEVEL
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(Original post by charco)
Which circled X?
In the red circle, + x
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Turtlebunny
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Are you referring as to where to put the positive charge?

The electrophilic aromatic substitution mechanism is an electrophilic attack followed by an alpha elimination. By alpha elimination I mean the hydrogen that is 'alpha' to the carbon with the positive charge on it is eliminated to restore aromaticity. In this context and in a lot of other Chemistry you may encounter alpha refers to the adjacent carbon 1 away from your positive charge/functional group/whatever. Knowing this, you know that the positive charge should be placed on the adjacent carbon to where you have your hydrogen and the electrophile you have added. The 3/4 completed ring is a notation to show a disruption of aromaticity and you draw this round the rest of the ring - it comes from the resonance structures when you move the positive charge around your intermediate.
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charco
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(Original post by JanaALEVEL)
In the red circle, + x
Maybe it's my old eyes, but I can only see a plus sign in the circled structure. The previous poster has given a perfect explanation.
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JanaALEVEL
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#6
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#6
(Original post by charco)
Maybe it's my old eyes, but I can only see a plus sign in the circled structure. The previous poster has given a perfect explanation.
Oh you were kidding (?)

Finding an x on the phone is much easier than finding a plus, and it surely does the job.

P.s, if you rotate the plus sign a little, you'll get an x
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