Chapter 18: Aryl and Vinylic Halides, Phenols Flashcards
1
Q
Aryl Halogen
A
- halogen attached directly to aromatic ring
2
Q
Vinyl Halogen
A
- halogen attached directly to DB
3
Q
Aryl and Vinyllic halogens DO NOT undergo ____
A
SN2 substitution
4
Q
Why is SN2 unfavorable for vinyllic halogens?
A
- high energy transition state
- rehybridization required
- also steric hindrance
5
Q
Why is SN2 unfavorable for aryl halogens?
A
- nucleophile would have to go through the ring to do backside attack
6
Q
Vinyl and Aryl halogens DO undergo _____
A
elimination reactions (at very high temperatures)
7
Q
For Aryl and Vinyl halogens ____ reactions don’t work very well either. Why?
A
- SN1
- carbocations have no resonance stabilization
- carbocation is in p-orbital perpendicular to others, so can’t resonate
8
Q
A
Phenol
9
Q
Acidity of phenol
A
- O-H quite acidic, because conjugate base is stabilized by resonance
10
Q
Phenols are good for ____
A
E.A.S
11
Q
A
- mild conditions w/o catalyst, brominates once
12
Q
A
- super fast, can’t stop at just one bromine addition
- because H2O deprotonates -OH
- conjugate base is very resonance stabilized
- because H2O deprotonates -OH
