Nucleophilicity order

Question

ch3br +nu^- →ch3-nu +br^- . The decreasing order of rate of above reaction with nucleophile nu- is

A)pho^_

^{B) ACO-}

^c)Ho-

^{D) ch3o-}

Answer 1

The decreasing order of rate of above reaction with nucleophile nu- is

CH₃O^– > HO^– > PhO^– > AcO^– 

Explanation:

If the nucleophilic atom or the centre is same, more basic the species stronger is the nucleophile. 

Here, the nucleophilic atom i.e. O is the same in all these species. This order can be easily explained on the general concept that a weaker acid has a stronger conjugate base.