Question

The increasing order of nucleophilicity of the following nucleophiles is:
a.) $C{{H}_{3}}C\overset{-}{\mathop{{{O}_{2}}}}\,$
b.) ${{H}_{2}}O$
c.) $C{{H}_{3}}S\overset{-}{\mathop{{{O}_{3}}}}\,$
d.) $\overset{-}{\mathop{O}}\,H$

A.) (b) < (c) < (a)< (d)
B.) (a) < (d) < (c)< (b)
C.) (d) < (a) < (c)< (b)
D.) (b) < (c) < (d)< (a)

Answer 1

Hint:. Nucleophilicity is compared using the size of the given nucleophile. If we know the concept of nucleophilicity it would be very easy to answer the question. Nucleophiles are the electrons rich species.

Complete step by step answer:
Nucleophilicity is the tendency to donate electrons to an electrophile which is an electron deficient species. Here $\overset{-}{\mathop{O}}\,H$ is the strongest nucleophile among the following because the oxygen in $\overset{-}{\mathop{O}}\,H$ is a strong base and a strong base is a good nucleophile. After $\overset{-}{\mathop{O}}\,H$ , $C{{H}_{3}}C\overset{-}{\mathop{{{O}_{2}}}}\,$ is the strong nucleophile because it has the negative charge which in this case the oxygen atoms has more electrons has more electrons on it, but a fact is that $C{{H}_{3}}C\overset{-}{\mathop{{{O}_{2}}}}\,$ is a weak base. So it is not important that strong bases are good nucleophiles. ${{H}_{2}}O$ is the weakest nucleophile.
So, the correct answer is “Option A”.

Additional Information:
There are four factors that affect nucleophilicity, there are charges, electronegativity, solvent and the steric factor.
The conjugate bases are always a better nucleophile. Hydroxide ions are always a better nucleophile than water.

Note: Don’t get confused between the basicity and nucleophilicity. Remember that basicity is the subset of nucleophilicity. All the nucleophiles are Lewis bases because they donate a pair of electrons. A base is just the name which we give to a nucleophile while it forms a bond with the proton. It is not important that strong bases are good nucleophiles.