NGP By An Aromatic Ring
In the case of a benzyl halide the reactivity is higher for the because the SN2 transition state enjoys a similar overlap effect to that in the allyl system.
An aromatic ring can assist in the formation of a carbocationic intermediate called a phenonium ion by delocalising the positive charge.
When the following tosylate reacts with acetic acid in solvolysis then rather than a simple SN2 reaction forming B, a 48:48:4 mixture of A, B and (C+D) was obtained .
The mechanism which forms A and B is shown below.
Read more about this topic: Neighbouring Group Participation
Famous quotes containing the words aromatic and/or ring:
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—Alexander Pope (1688–1744)
“I was exceedingly interested by this phenomenon, and already felt paid for my journey. It could hardly have thrilled me more if it had taken the form of letters, or of the human face. If I had met with this ring of light while groping in this forest alone, away from any fire, I should have been still more surprised. I little thought that there was such a light shining in the darkness of the wilderness for me.”
—Henry David Thoreau (1817–1862)