Question

Decreasing order of nucleophilicity is:
A. \[O{H^ - } > N{H_2}^ - > C{H_3}{O^ - } > RN{H_2}\]
B. \[N{H_2}^ - > O{H^ - } > C{H_3}{O^ - } > RN{H_2}\]
C. \[N{H_2}^ - > C{H_3}{O^ - } > O{H^ - } > RN{H_2}\]
D. \[C{H_3}{O^ - } > N{H_2}^ - > O{H^ - } > RN{H_2}\]

Answer 1

Hint: To answer this question you need to know the order of basicity of the elements because more basic the ion more is its nucleophilicity.

Complete step by step answer:
Nucleophilicity also referred to as nucleophile strength refers to a substance’s nucleophilic character and is often used to compare the affinity of atoms. Neutral nucleophile reactions with solvents such as alcohols and water are named solvolysis. They may take part in nucleophilic substitution whereby a nucleophile becomes attracted to a full or partial positive charge. Nucleophilic describes the affinity of a nucleophile to the positively charged atomic nuclei of atoms. They are chemical species that donates an electron pair to form a chemical bond in relation to a reaction. All atoms or ions with a free pair of electrons or at least one pi bond tend to act as nucleophiles.
Now, as we observe the atoms in the options, the atoms are in the same row of periodic tables. And if the nucleophilic atoms are in the same row of periodic table then nucleophilicity is approximately in order of basicity. Therefore the correct order is \[N{H_2}^ - > C{H_3}{O^ - } > O{H^ - } > RN{H_2}\] .

So, the correct option is C.

Additional Information:
The term nucleophile and electrophile were introduced by Christopher Kelk Ingold in 1933. In general in a group across the periodic table, the more basic the ion the more reactive it is as a nucleophile. Many different schemes attempting to quantify relative nucleophilic strength have been devised. Some examples are Swain-Scott equation, Ritchie equation, Mayr-Patz equation and Unified equation.

Note:
Here we noted that nucleophilicity is decided by the order of basicity. The more basicity means more nucleophilicity.
Nucleophiles have a tendency to attack substances which have higher electron deficiency.