ARENES AND ARO 255 11.6(b) Only the benzylic hydrogen is replaced by bromine in the reaction of 4-methyl-3-nitroanisole with N-bromosuccinimide OCH OCH Only these hydrogens 11.7 The lecular formula of the product is CuH,O4. Since it contains four oxygens, the product must have two-CO,H groups. None of the hydrogens of a tert-butyl substituent on a benzene i benzylic, and so this group is inert to oxidation. Only the benzylic methyl groups of 4-tert-butyl-1, 2 dimethylbenzene are susceptible to oxidation; therefore, the product is 4-tert-butylbenzene-1, 2 dicarboxylic acid. (CH3)C. (CH3)3C Nac y to oxidation 1, 2-dicarboxylic acid 11.8 Each of these reactions involves nucleophilic substitution of the SN2 type at the benzylic position of (b)(CH3)3C CH,OC(CH3) tert-Butoxid Benzyl bromide Benzyl ter-butyl ether (c) =N=N: CH-Br CHN Azide i (d) HS CH—B CHSH CH,I lodide ion Benzyl bromide Back Forward Main Menu TOC Study Guide Toc Student OLC MHHE Website11.6 (b) Only the benzylic hydrogen is replaced by bromine in the reaction of 4-methyl-3-nitroanisole with N-bromosuccinimide. 11.7 The molecular formula of the product is C12H14O4. Since it contains four oxygens, the product must have two @CO2H groups. None of the hydrogens of a tert-butyl substituent on a benzene ring is benzylic, and so this group is inert to oxidation. Only the benzylic methyl groups of 4-tert-butyl-1,2- dimethylbenzene are susceptible to oxidation; therefore, the product is 4-tert-butylbenzene-1,2- dicarboxylic acid. 11.8 Each of these reactions involves nucleophilic substitution of the SN2 type at the benzylic position of benzyl bromide. (b) (c) (d) (e) CH2I Benzyl iodide CH2 Br Benzyl bromide I  Iodide ion CH2SH Phenylmethanethiol CH2 Br Benzyl bromide HS  Hydrogen sulfide ion N  N CH2N Benzyl azide CH2 Br Benzyl bromide N N  N Azide ion CH2OC(CH3)3 Benzyl tert-butyl ether CH2 Br Benzyl bromide (CH3)3CO  tert-Butoxide ion CH3 CH3 (CH3)3C Susceptible to oxidation Not benzylic hydrogens; not readily oxidized Na2Cr2O7 H2O, H2SO4, heat CO2H CO2H (CH3)3C 4-tert-Butylbenzene- 1,2-dicarboxylic acid CH2Br OCH3 NO2 CH3 OCH3 NO2 Only these hydrogens are benzylic. NBS 80C, peroxides ARENES AND AROMATICITY 255 Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website