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 .
About Author: admin

Comments are closed.

Find us on Facebook