Orientation of Benzene



ORIENTATION IN BENZENE
ORIENTATION IN BENZENE
 All hydrogen atoms of the benzene ring are equivalent. Therefore,when a group enters into the     benzene ring, only one monosubstituted product (C6H5-G) is possible as described below:

 Problem starts when another group (E+) or second substituent enters into monosubstituted benzene     and it can occupy any one of the remaining five positions as shown below:.
  
 But which one of the five positions the new group will occupy??? Let us discuss the exact possibility.
EFFECT OF SUBSTITUENTS ON FURTHER SUBSTITUTION
 Positions 2 and 6 are same (ortho product)
 Positions 3 and 5 are same (meta product)
 Position 4 is para position
  
INFLUENCE OF SUBSTITUENT
 A substituent (G) already present on the benzene ring imparts two types of influence on benzene         ring for further substitution. 
   Directive effect
   Activity effect
DIRECTIVE OR ORIENTATION EFFECT
 The first substituent (G) may direct the next incoming group (E+) to ortho, meta or para position,     depending on the nature of the first substituent. This is called directive or orientation effect.
ACTIVITY EFFECT
 The substituent already present may activate or deactivate the benzene ring towards further     substitution. These effects are called the activity effects.
DIRECTIVE EFFECTS OF SUBSTITUENTS
 In monosubstituted benzene, C6H5-G, there are five hydrogen atoms.
   Ortho = 2 positions
   Meta = 2 positions
   Para = 1 position
 But, this distribution is never obtained. The products formed, in fact,is determined by the nature of     the first substituent already present on the ring .

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