PHENOLS It is also possible that the elimination stage of the reaction proceeds as follows + ho H,C- OH Cyclohexadienyl anion H H OH H C so,+ H,o p-Methylphenoxide ion 24.5 The text states that the hydrolysis of chlorobenzene in base follows an elimination-addition mechanism H + Ho+c Chlorobenzene -OH Benzyne 24.6 (b) The reaction is Friedel-Crafts alkylation. Proton transfer from sulfuric acid to 2-methyl- propene gives tert-butyl cation. Because the position para to the hydroxyl substituent already bears a bromine, the tert-butyl cation attacks the ring at the position ortho to the sOa B 2-Methylpropene methylphenol (c) Acidification of sodium nitrite produces nitrous acid, which nitrosates the strongly activated aromatic ring of phenols H HC HC 2-lsopropyl-5-methylphenol 2-Isopropyl-5-methyl-4-nitrosophenol isolated yield, Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website678 PHENOLS It is also possible that the elimination stage of the reaction proceeds as follows: 24.5 The text states that the hydrolysis of chlorobenzene in base follows an elimination–addition mechanism. 24.6 (b) The reaction is Friedel–Crafts alkylation. Proton transfer from sulfuric acid to 2-methyl￾propene gives tert-butyl cation. Because the position para to the hydroxyl substituent already bears a bromine, the tert-butyl cation attacks the ring at the position ortho to the hydroxyl. (c) Acidification of sodium nitrite produces nitrous acid, which nitrosates the strongly activated aromatic ring of phenols. CH(CH3)2 OH H3C NaNO2 HCl, H2O CH(CH3)2 OH N O H3C 2-Isopropyl-5-methylphenol 2-Isopropyl-5-methyl-4-nitrosophenol (isolated yield, 87%) H2SO4 (CH3)2C OH CH3 CH2 Br (CH3)3C OH CH3 Br  4-Bromo-2- methylphenol 4-Bromo-2-tert-butyl- 6-methylphenol (isolated yield, 70%) 2-Methylpropene OH OH Phenol OH  Benzyne H2O OH   H2O Cl  H Cl Chlorobenzene Benzyne   H2O Cyclohexadienyl anion intermediate H3C SO3 OH H H3C SO3 O H H H SO3 2   H2O OH H3C H H O OH p-Methylphenoxide ion H3C O HO Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website