Hydrocarbons - Result Question 75
####77. The order of decreasing reactivity towards an electrophilic reagent, for the following would be
[2007] (i) benzene (ii) toluene (iii) chlorobenzene (iv) phenol
(a) (ii) $>$ (iv) $>$ (i) $>$ (iii) (b) (iv) $>$ (iii) $>$ (ii) $>$ (i)
(c) (iv) $>$ (ii) $>$ (i) $>$ (iii) (d) (i) $>$ (ii) $>$ (iii) $>$ (iv)
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Solution:
- (c) Electrophiles have high affinity for electrons. They attack at the site where electron-density is highest. Electron donating groups increases the electron density. The electron donating tendency decreases in the order :
$ -OH>-CH_3>-H>-Cl $
Therefore, the correct order of reactivity towards electrophile is
$ C_6 H_5 OH>C_6 H_5 CH_3>C_6 H_6>C_6 H_5 Cl $
78 .
(c)
