Question

Which one of the following has maximum nucleophilicity?

• A. $C{H}_3{S}^{\ominus }$
• B. $C_6{H}_5-\stackrel{\ominus }{O}$
• C. $E{t}_{3}N$
• D. $F^{\ominus }$

Answer 1

The correct option is A $C{H}_3{S}^{\ominus }$

In general, anionic nucleophile is stronger than a neutral Nucleophile.
$E{t}_{3}N$ is a neutal nucleophile so it does not have much nucleophilicity.

In (b), the negative charge on oxygen is delocalised on benzene and stabilise the molecule. Therefore it is a weak nucleophile.

In (d), negative charge is on F which is a strong electron withdrawing group so it stabilise the negative charge on it.

In (a), negative charge is on S, which is less electronegative element than F and the presence of +I group $(C{H}_3$) will increase electron density on S and destabilise it. Thus, it shows maximum nucleophilicity.