How Do Existing Substituents on Benzene Affect Electrophilic Aromatic Substitution

STEP 3 Take a proton away. Proton transfer from this intermediate to dihydrogen phosphate ion gives isopropylbenzene  

Write a mechanism for the formation of ferf-butylbenzene from benzene and fert-butyl alcohol in the presence of phosphoric acid. 

Comparison of Alkene Addition and Electrophilic Aromatic Substitution (EAS) 

Electrophilic aromatic substitution represents the second instance in which we have encountered a C = C double bond attacking an electrophile. The first instance was in our discussion of alkene addition reactions in Section 5.3. Notice the similarities in the first step where a C = C double bond attacks an electrophilic atom (H or E ). In Step 2, however, alkene addition results in the attack of a nucleophile on the carbocation, while EAS results in abstraction of a hydrogen by base. In one reaction, the C = C double bond is destroyed, while in the other, the C = C double bond is regenerated. 

How Do Existing Substituents on Benzene Affect Electrophilic Aromatic Substitution  

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