Question

Explain the term nucleophile. Give examples.

Answer 1

i. The species which donate (give away) electron pairs to the substrate during the reaction are called nucleophiles. 

ii. Since, nucleophiles are electron rich species, they donate a pair of electrons to acceptor atoms and thus, they are nucleus seeking (or nucleus loving) species.

iii. e.g. a. Negatively charged nucleophiles:

OH^- , CN^- , Cl^- , Br^- , etc.

b. Neutral species containing at least one lone pair of electrons: 

H₂O, NH₃ , H₂S, R – OH, R – NH₂ , R – OR, etc.

iv. A polyatomic nucleophile has an electron rich atom in it called the nucleophilic centre. 

e.g. The nucleophilic centre of the nucleophile H₂O is ‘O’ which has two lone pairs of electrons.