adulter
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how do you know whether a group has an donating effect or withdrawing effect when determining which carbon in a double bond is the carbocation
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Lily2108
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(Original post by adulter)
how do you know whether a group has an donating effect or withdrawing effect when determining which carbon in a double bond is the carbocation
I think whichever Carbon atom ‘opens’ the double bond in the mechanism and bonds to the electrophile is not the carbocation, it’s always the other one, as this Carbon becomes electron-deficient and has a positive charge. Therefore the groups surroundings the Carbocation will have an electron-donating effect as they make the ion more stable.
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Kallisto
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Are you sure that we are not talking about electrophilic substitution?

In general EWG and EDG depends on the effects, chemists make differents for two: the positive inductive (+I) or mesomeric (+M) and the negative inductive (-I) or mesomeric (-M) effect. According to what kind of effects you have electrons are donating or withdrawing in a conjugated pi system. This conjugated system is nothing more than a bond with alternating single or double bond in a aromatic compound.

When you have a positive mesomeric or inductive effect, the electrons get attracted by the activating group. In this case it is an electron donating group.

When it is a negative inductive or mesomeric effect, the electrons get removed by the activating group. That is an electron withdrawing group then.

The link below show you all kinds of groups for both effects:

https://en.wikipedia.org/wiki/Electr...recting_groups
Last edited by Kallisto; 1 year ago
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