CHM 2211C           Chapter 16: Chemistry of Benzene:

                                Electrophilic Aromatic Substitution

Part D: Predicting Orientation in Disubstituted Benzenes:

Rules:

1.       If the groups reinforce each other, the orientation can be inferred from either group.

 

2.       If the op-director and the m-director are not reinforcing, the op-director controls the orientation.

            (The incoming group goes mainly ortho to the m-director),

 

3.       A strongly activating group, competing with a weakly activating group, controls the orientation.

 

4.       When two weakly activating or deactivating groups or two strongly activating or deactivating groups compete, substantial amounts of both isomers are obtained; there is little preference.

 

5.       Very little substitution occurs in the sterically hindered position between meta substituents.

 

6.       Very little substitution occurs ortho to a bulky op-directing group such as t-butyl.

 

Indicate by an arrow the position(s) most likely to undergo electrophilic substitution in each of the following compounds. The list the rule(s) under the structure used in making your prediction.

 

  1. m-xylene           2. p-nitrotoluene         3.  m-chloronitrobenzene         

 

 

 

 

 

 

 

    4. p-methoxytoluene         5. p-chlorotoluene     6. m-nitrotoluene      

 

 

 

 

 

 

 

 

 7. o-methylphenol (o-cresol)     8. o-xylene

 

 

 

 

 

 

 

 

      9.  p-xylene            10.  m-cyanotoluene   (m-toluonitrile)