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Solutions to Problems 323 43. Orientation of reaction is determined by more activating (or less deactivating) substituent (marked in each case below). Again, the para product can be expected to predominate where a choice of ortho or para exists. NO₂ NO₂ CI CI (a) (b) CH₃ CH₃ SO₃H CI CH₃ COOH COOH CH₃CH₂ CH₃CH₂ (c) NO₂ NO₂ Br (d) + CH₃ CH₃ Br SO₃H CH₃ (e) (f) Br CCH₃ HO₃S NO₂ OCH₃ (Both meta directing) NO₂ Ortho to this NO₂ (g) (h) NO₂ 1 NO₂ Para to this The saturated ring is not special. Treat it just like two alkyl groups. (i) No reaction. Friedel-Crafts reaction does not occur on rings containing meta-directing groups: The ring is too deactivated. 44. (a) Activation effects are additive. 1,3-Dimethylbenzene (m-xylene) differs from its 1,2 and 1,4 isomers because it is the only one that contains ring positions activated by both methyl substituents. Electrophilic substitution at C2, C4, and C6 (which is equivalent to C4) gives intermediate cations