Haloalkanes and Haloarenes - Result Question 14
####14. For (i) $I^{-}$, (ii) $Cl^{-}$, (iii) $Br^{-}$, the increasing order of nucleophilicity would be
[2007]
(a) $Cl^{-}<Br^{-}<I^{-}$
(b) $I^{-}<Cl^{-}<Br^{-}$
(c) $Br^{-}<Cl^{-}<I^{-}$
(d) $I^{-}<Br^{-}<Cl^{-}$
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Solution:
- (a) Nucleophilicity increases down the periodic table : $I^{-}>Br^{-}>Cl^{-}>F^{-}$
Nucleophilicity governs the kinetics of a reaction while basicitydetermines its thermodynamics.
Since, electronegativity decreases down the group (or electropositivity increases), nucleophilicity also increases down the group. But the order of basicity is:
$I^{-}<Br^{-}<Cl^{-}<F^{-}$
