1559reh16291-30311/3/0510:02Page297 exist ⊕ h meta di ontaining meta-directing groups:The 39.(a)o additive Electrophilic substitution atCC4.and C6(which is equivalent to C)gives intermediate cationsSolutions to Problems • 297 38. 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. (a) (b) (c) (d) (e) (f) (g) (h) (i) No reaction. Friedel-Crafts reaction does not occur on rings containing meta-directing groups: The ring is too deactivated. 39. (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 NHCOCH3 NO2 Cl NO2 NO2 NO2 NO2 Para to this Ortho to this The saturated ring is not special. Treat it just like two alkyl groups. OCH3 HO3S CH3 CCH3 NO2 SO3H Br O (Both meta directing) NHCOCH3 CH3 Br NHCOCH3 CH3 Br COOH NO2 CH3CH2 COOH NO2 CH3CH2 Cl SO3H Cl CH3 Cl NO2 CH3 NO2 CH3 1559T_ch16_291-303 11/3/05 10:02 Page 297