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?
Naphthalene undergoes eletrophilic substitution at C-1.
Why is this the case, even though substitution at C-2 gives more resonance forms?
Draw in the arrows to show the electron flow and resonance forms in the nucleophilic aromatic substitution reaction below.
Note: Depending on the textbook, nucleophilic aromatic substitution is referred to as NAS, SNAr, or addition-elimination.
Draw a mechanism for the nucleophilic aromatic substitution (SNAr) reaction below. Show all resonance forms of the intermediate.
Let's go through a benzyne reaction (also called elimination-addition).
In the reaction below, the strong base (NaNH2) will form a benzyne intermediate, which when forms either ortho nitroaniline or meta nitroaniline.
Used curved arrows to show the formation of each intermediate and the final products.
Let's go through another way to make benzyne.
First, let's form a Grignard reagent. Then, let's elminate to form benzyne.
The nitrosyl cation is shown below. Also shown are several proposed resonance arrows, only one of which is correct.
Draw the resonance forms that would follow from each set of arrows, and include formal charges. Which one is the correct resonance form? Explain your reasoning.
