Nucleophilic aromatic substitution?
Hello, can someone answer the question why a nucleophilic attack always occurs on a halogen?
Thanks, LG
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Doesn't have to be a halogen, but a leaving group that can take electrons, so to speak. Because the leaving group leaves the molecule formally as X^-. In the case of, for example, hydrogen, the H would have to go out as H^- and this will not happen.
The attack is also done by a nucleophile. Accordingly, a positively polarized center is advantageous as an attack point for the nucleophile. You don't have that with a CH bond.
Okay, thanks. Do you also happen to have certain conditions to prevail so that a nucleophilic aromatic substitution takes place? So especially warm or something. Compared to electrophilic aromatic substitution
This depends on your exact system, but in principle you need a good leaving group and a reduced electron density in the ring (eg by an electron-withdrawing group). The latter activates the ring. Without this, for example, an unsubstituted benzene will not react.