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Preparation of ethers: Williamson Ether Synthesis General reaction: SN2 RONa + R'Br ROR' + NaBr prepare alkoxide OH ONa 2 Na 2 2 + H2 OCH2CH3 Na O + CH3CH2 Br + NaBr This is an SN2 reaction, thus the alkyl halide should be primary or methyl. Dehydration of Alcohols to make symmetrical ethers OH 2 H 3O H2SO4(aq) 140oC O + H 2O OH2 H O + H 2O Alkoxymercuration/demercuration OCH3 1) Hg(OAc)2 in CH3OH 2) NaBH4 Mechanism is Markovnikov oxymercuration HgOAc OAc + δ OAc Hg Hg(OAc)2 in CH3OH Hg δ Hg + OCH3 H OAc OCH3 OAc H NaBH4 (H ) OCH3 OCH3 H Reactions of ethers: Cleavage with HI or HBr H Br HBr O H O Br SN2 OAc Br OH + examples (provide the mechanism): O OH HI I OCH(CH3)2 HBr E2 OH + CH2=CHCH3 + HBr