Question

Which of the following is an electrophile?
A. \[{\text{:CC}}{{\text{l}}_{\text{2}}}\]
B. \[{\text{C}}{{\text{H}}_{\text{3}}}^{\text{ - }}\]
C. \[{{\text{H}}_{\text{2}}}{\text{O}}\]
D. \[{\text{N}}{{\text{H}}_{\text{3}}}\]

Answer 1

Hint:Electrophile is an electron-deficient species. It tends to accept electrons. Determine the species that has less number of electrons.

Complete answer:
An electrophile is a species having an electron-deficient atom or center. Due to the deficiency of electrons, they tend to gain electrons.

A. The species given in option A is\[{\text{:CC}}{{\text{l}}_{\text{2}}}\]. It is dichlorocarbene. The structure of \[{\text{:CC}}{{\text{l}}_{\text{2}}}\] is as follows:

Here, the central carbon atom is surrounded by 6 electrons so we can say that it is an electron-deficient species. So, dichlorocarbene \[{\text{:CC}}{{\text{l}}_{\text{2}}}\] is an electrophile.
Thus, option (A) \[{\text{:CC}}{{\text{l}}_{\text{2}}}\] is correct.

B. The species given in option B is\[{\text{C}}{{\text{H}}_{\text{3}}}^{\text{ - }}\]. The structure of \[{\text{C}}{{\text{H}}_{\text{3}}}^{\text{ - }}\] is as follows:

Here, the central carbon atom is surrounded by 8 electrons so we can say that it is an electron-rich species. So, we cannot consider \[{\text{C}}{{\text{H}}_{\text{3}}}^{\text{ - }}\] as an electrophile.
Thus, option (B) \[{\text{C}}{{\text{H}}_{\text{3}}}^{\text{ - }}\] is incorrect.

C. The species given in option C is\[{{\text{H}}_{\text{2}}}{\text{O}}\]. The structure of \[{{\text{H}}_{\text{2}}}{\text{O}}\] is as follows:

Here, the central oxygen atom is surrounded by 8 electrons so we can say that it is an electron-rich species. So, we cannot consider \[{{\text{H}}_{\text{2}}}{\text{O}}\] as an electrophile.
Thus, option (C) \[{{\text{H}}_{\text{2}}}{\text{O}}\] is incorrect.

D. The species given in option D is\[{\text{N}}{{\text{H}}_{\text{3}}}\]. The structure of \[{\text{N}}{{\text{H}}_{\text{3}}}\] is as follows:

Here, the central nitrogen atom is surrounded by 8 electrons so we can say that it is an electron-rich species. So, we cannot consider \[{\text{N}}{{\text{H}}_{\text{3}}}\] as an electrophile.
Thus, option (D) \[{\text{N}}{{\text{H}}_{\text{3}}}\]is incorrect.

Hence, the correct option is (A) \[{\text{:CC}}{{\text{l}}_{\text{2}}}\].

Note:
Carbene are neutral species having a carbon atom with two bonds. In carbene central carbon atoms are surrounded by 6 electrons. As the octet of central carbon in carbene is incomplete they are known as electrophile.