11.10Reactions of Arenes:A Preview,1. Some reactions involve the ring. 2. In other reactions the ring is a substituent.,a) Reduction Catalytic hydrogenation (Section 11.4) Birch reduction (Section 11.11) b) Electrophilic aromatic substitution(Chapter 12) c) Nucleophilic aromatic substitution(Chapter 23),1. Reactions involving the ring,2. The ring as a substituent (Sections 11.12-11.17),catalytic hydrogenation (Section 11.4),Birch reduction (Section 11.11),Reduction of Benzene Rings,11.11The Birch Reduction,(80%),Na, NH3,CH3OH,Birch Reduction of Benzene,Product is non-conjugated diene. Reaction stops here. There is no further reduction. Reaction is not hydrogenation. H2 is not involved in any way.,Step 1: Electron transfer from sodium,+,Mechanism of the Birch Reduction (Figure 11.8),Step 2: Proton transfer from methanol,Mechanism of the Birch Reduction (Figure 11.8),H,H,H,H,H,H,Step 2: Proton transfer from methanol,Mechanism of the Birch Reduction (Figure 11.8),H,H,H,H,H,H,H,H,H,H,H,H,H,Step 3: Electron transfer from sodium,Mechanism of the Birch Reduction (Figure 11.8),Step 3: Electron transfer from sodium,Mechanism of the Birch Reduction (Figure 11.8),H,H,H,H,H,H,H,+,Na+,Step 4: Proton transfer from methanol,Mechanism of the Birch Reduction (Figure 11.8),H,H,H,H,H,H,H,Step 4: Proton transfer from methanol,Mechanism of the Birch Reduction (Figure 11.8),H,H,H,H,H,H,H,(86%),Na, NH3,CH3OH,Birch Reduction of an Alkylbenzene,If an alkyl group is present on the ring, it ends up asa substituent on the double bond.,