Description: Covers electrophilic aromatic substitution (EAS) reactions in detail.
It includes many, many resonance exercises that show why:
Total Problems: 11
Use curved arrows to draw a mechanism for the generic electrophilic aromatic substitution (EAS) reaction below.
Indicate the eletrophile formed by each set of reagents/conditions below.
Phenol can be prepared from benzene and hydrogen peroxide in the presence of a really strong acid. Propose a mechanism for this reaction.
Let's draw resonance forms to see why some groups are EDG or EWG. (I've started you off)
Where are the positive or negative charges placed in EDG/EWG? (ortho/meta/para) Why would this affect EAS reactions?
Note: EDG = electron donating group, EWG = electron withdrawing group
-OR is an EDG and an ortho-para director. Let's draw an EAS reaction's cyclohexadienyl cation intermediates to demonstrate why this is true. I've started you off.
What's good about ortho/para? What's bad about meta?
-NO2 is an EWG and a meta director. Let's draw an EAS reaction's cyclohexadienyl cation intermediates to demonstrate why this is true. I've started you off.
What's good about meta? What's bad about ortho/para?
Pyrrole undergoes eletrophilic aromatic substitution at C-2. Let's compare the resonance forms of EAS carbocation intermediates to see why this is the case. What do you think? Why C-2 and not C-3?
Naphthalene undergoes eletrophilic substitution at C-1.
Why is this the case, even though substitution at C-2 gives more resonance forms?
a) Rationalize the relative stabilities of the cation species below.
b) Pyridine undergoes eletrophilic substitution at C-3. Let's compare the resonance forms of EAS carbocation intermediates to see why this is the case. Consider part a) in your explanation.
A chemist tried to prepare compound A from benzene via Friedel-Crafts alkylation and instead produced compound B.
Why did this happen? How could the chemist prepare compound A?
Show how to prepare vinyl benzene from benzene.