Question

Among the following nucleophiles in the order of their nucleophilic strength.
A. $O{H^ - } > C{H_3}CO{O^ - } > OC{H_3}^ - > {C_6}{H_6}{O^ - }$
B. $C{H_3}CO{O^ - } < {C_6}{H_6}{O^ - } < OC{H_3}^ - < O{H^ - }$
C. ${C_6}{H_6}{O^ - } < C{H_3}CO{O^ - } < OC{H_3}^ - < O{H^ - }$
D. $C{H_3}CO{O^ - } < {C_6}{H_6}{O^ - } < O{H^ - } < OC{H_3}^ -$

Answer 1

The nucleophilicity of different nucleophiles depends on many things. And among them one of them is, increasing base strength means they have decreasing nucleophilic strength.

Complete step by step solution:
We know that the nucleophiles are the electron-rich species in search of nucleus or positive centre, (Nucleus-nucleus, phile-loving). Therefore, these can be either negatively charged or even neutral.
According to the question we have 4 nucleophiles given,
$O{H^ - },C{H_3}CO{O^ - },OC{H_3}^ - ,{C_6}{H_6}{O^ - }$
We can see that all of them have a negative charge therefore all are nucleophiles. And now what determines their nucleophilic strength is whether they have a good electron releasing group is attached to them or not.
Since when they are in search of positivity, it should have a greater tendency to donate ions or valence electrons. This is why we say an increase in base strength means a decrease in nucleophilic strength because the tendency to attract positive species becomes less.
Now for these given species, we can check their $+ I$ effect. The $+ I$ effect gives us the idea of how much they can attract the positive species because the increase in $+ I$ means an increase in basic strength which implies a decrease in nucleophilic strength and vice-versa
Therefore we just have to check the decreasing order of $+ I$ effect.
When we compare $O{H^ - }$and $OC{H_3}^ -$, we can see $OC{H_3}^ -$ has more $+ I$ effect as it has $- {\text{C}}{{\text{H}}_3}$ attached to it. Therefore, $O{H^ - }$ has more nucleophilic strength than $OC{H_3}^ -$.
Now when we compare between $C{H_3}CO{O^ - }$ and $OC{H_3}^ -$we can see that $C{H_3}CO{O^ - }$ has lesser $+ I$ effect therefore, it will have lesser nucleophilic strength.
Now when we compare between $C{H_3}CO{O^ - }$ and ${C_6}{H_6}{O^ -}$. ${C_6}{H_6}{O^ - }$ has less $+ I$ effect therefore, it will have lesser nucleophilic strength when compared to $C{H_3}CO{O^ - }$.
Finally, their order will be
${C_6}{H_6}{O^ - } < C{H_3}CO{O^ - } < OC{H_3}^ - < O{H^ - }$

**Therefore, Option C is correct.

Note:**
Some of the other things to note is that
1. Nucleophilicity increases down the group in the periodic table.
2. Order of nucleophilicity is the reverse order of basicity.
3. Lesser the electronegativity of donor atoms more is its tendency to give a lone pair of electrons and thus more is its nucleophilic strength.