Question

The most reactive nucleophile among the following is:
(A) $C{H_3}{O^ - }$
(B) ${C_6}{H_5}{O^ - }$
(C) ${\left( {C{H_3}} \right)_2}CH{O^ - }$
(D) ${\left( {C{H_3}} \right)_2}C{O^ - }$

Answer 1

Hint : The reagents are of different types. The molecules or groups or reagents undergo reduction or oxidation. The nucleophiles or electrophiles are groups. Nucleophiles are electron-hating groups as they are attracted to electron deficient compounds to occur a chemical change.

Complete Step By Step Answer:
Reagents or groups are of different types. Based on the charge present on the groups these are classified into two types. Electrophiles and nucleophiles. Electrophiles are electron-loving groups as they are deficient of electrons attracted by electron rich compounds. Nucleophiles are electron rich species and attract electron deficient compounds.
Given compounds are nucleophiles.
The first one is methoxide ion $C{H_3}{O^ - }$ . It has a methyl group and it is an electron-pushing group that increases the charge and is most reactive.
The second one is phenoxide ion ${C_6}{H_5}{O^ - }$ the negative charge involves resonance and thus is not more reactive than methoxide ion.
The third one is isopropyl alkoxide ${\left( {C{H_3}} \right)_2}CH{O^ - }$ and due to presence of two methyl groups the negative charge involved in steric hindrance and not more reactive than methoxide ion.
The fourth one is acetone ${\left( {C{H_3}} \right)_2}C{O^ - }$ with negative charge, due to the presence of steric hindrance, it is not more reactive than methoxide ion
Thus, methoxide ion $C{H_3}{O^ - }$ is the most reactive nucleophile.
Option A is the correct one.

Note :
The negative charge on the nucleophile will be increased by the presence of methyl groups as the methyl group is an electron pushing group. But due to steric hindrance the methoxide is more reactive than the nucleophiles with methyl groups.