● CHAPTER 12 REACTIONS OF ARENES ELECTROPHILIC AROMATIC SUBSTITUTION n the preceding chapter the special stability of benzene was described, along with reac tions in which an aromatic ring was present as a substituent. In the present chapter we move from considering the aromatic ring as a substituent to studying it as a functional group. What kind of reactions are available to benzene and its derivatives? What sort of reagents react with arenes, and what products are formed in those reactions? Characteristically, the reagents that react with the aromatic ring of benzene and its derivatives are electrophiles. We already have some experience with electrophilic reagents, particularly with respect to how they react with alkenes. Electrophilic reagents dd to alkenes C=C+ Alkene Electrophilic Product of reagent electrophilic addition a different reaction takes place when electrophiles react with arenes. Substitution is observed instead of addition. If we represent an arene by the general formula ArH, where Ar stands for an aryl group, the electrophilic portion of the reagent replaces one of the hydrogens on the ring 生y Arene Electrophilic Product of electrophilic aromatic substitution 443 Back Forward Main MenuToc Study Guide ToC Student o MHHE Website443 CHAPTER 12 REACTIONS OF ARENES: ELECTROPHILIC AROMATIC SUBSTITUTION I n the preceding chapter the special stability of benzene was described, along with reac￾tions in which an aromatic ring was present as a substituent. In the present chapter we move from considering the aromatic ring as a substituent to studying it as a functional group. What kind of reactions are available to benzene and its derivatives? What sort of reagents react with arenes, and what products are formed in those reactions? Characteristically, the reagents that react with the aromatic ring of benzene and its derivatives are electrophiles. We already have some experience with electrophilic reagents, particularly with respect to how they react with alkenes. Electrophilic reagents add to alkenes. A different reaction takes place when electrophiles react with arenes. Substitution is observed instead of addition. If we represent an arene by the general formula ArH, where Ar stands for an aryl group, the electrophilic portion of the reagent replaces one of the hydrogens on the ring: Ar H Arene E Y  Electrophilic reagent Ar E H Y Product of electrophilic aromatic substitution C C Alkene E Y  Electrophilic reagent E C C Y Product of electrophilic addition Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website