Question

Nucleophilicity-${\text{C}}{{\text{H}}_{\text{3}}}{{\text{O}}^{\text{ - }}}$, ${\text{C}}{{\text{N}}^{\text{ - }}}$
Which is high ?

Answer 1

We must have to know that in organic chemistry, reagents are classified as two types. This type of classification is based on the charge of the attacking species in the reagents. Nucleophilic and electrophilic are classification of reagents. The charge of nucleophilic reagents is negative. The charge of electrophilic reagents is positive. The nucleophilic reagents are attacking positive charge in species. The electrophilic reagents are attacking negative charge in species. Some examples of nucleophilic reagents is${\text{N}}{{\text{H}}_{\text{3}}}$,${{\text{H}}_{\text{2}}}{\text{S}}$,${{\text{H}}_{\text{2}}}{\text{O}}$,${\text{C}}{{\text{l}}^{\text{ - }}}$,${{\text{I}}^{\text{ - }}}$,${\text{O}}{{\text{H}}^{\text{ - }}}$and ${\text{C}}{{\text{N}}^{\text{ - }}}$. Some examples of electrophilic reagents is ${\text{C}}{{\text{O}}_{\text{2}}}$,${\text{CC}}{{\text{l}}_{\text{2}}}$,${\text{AlC}}{{\text{l}}_{\text{3}}}$,${{\text{H}}^{\text{ + }}}$,${{\text{H}}_{\text{3}}}{{\text{O}}^{\text{ + }}}$,${\text{N}}{{\text{O}}^{\text{ + }}}$and $^{\text{ + }}{\text{N}}{{\text{O}}_{\text{2}}}$.

Complete answer:
The given nucleophilic reagents are ${\text{C}}{{\text{H}}_{\text{3}}}{{\text{O}}^{\text{ - }}}$ and${\text{C}}{{\text{N}}^{\text{ - }}}$.
Nucleophilicity of the nucleophilic reagents is dependent on the electronegativity of the molecules and polarity of the molecules. In the periodic table, the polarity of the molecules is moving from left to right.
Nucleophilicity of the nucleophilic reagents is responsible when the electronegativity of the molecules increases and polarity of the molecules decreases.
According above discussion, nucleophilicity of ${\text{C}}{{\text{N}}^{\text{ - }}}$is more than -${\text{C}}{{\text{H}}_{\text{3}}}{{\text{O}}^{\text{ - }}}$.
The electronegativity of the bond between carbon and oxygen is more than the electronegativity of the bond between carbon and nitrogen atoms.
The polarity of bond between carbon and oxygen is less than the polarity of bond between carbon and nitrogen atom.
Hence, nucleophilicity of ${\text{C}}{{\text{N}}^{\text{ - }}}$ is more than -${\text{C}}{{\text{H}}_{\text{3}}}{{\text{O}}^{\text{ - }}}$.

Note:
We must have to know that the halogen is the most electron affinity group in the periodic table. Halogen is also the most electronegativity group in the periodic table. The ionisation energy of the halogen is very less compared to other groups. In halogen from top to bottom, electron affinity decreases. Chlorine is the highest electron affinity species in the periodic table, because the size of the fluorine is very small compared to chlorine. But, the electronegativity value of fluorine is high compared to the electronegativity value of chlorine.