Which one is NOT a nucleophile?
Correct answer: A. BH3
- A. BH3
- B. NH3
- C. -NH2
- D. -OH
Explanation
A nucleophile is a chemical species that donates a lone pair of electrons to form a chemical bond to another electron deficient species. It therefore must always possess at least one lone pair in order to do this. In BH3, boron it is bonded to three hydrogen atoms. It has a valency of 3 so all of its valence electrons are used in bonding. Since no lone pairs are present, it cannot act as a nucleophile. Therefore, option A is the correct answer.
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About Nucleophilic Substitution
Nucleophilic substitution replaces a leaving group in an alkyl halide when an electron-rich nucleophile attacks the carbon atom. The topic compares SN1 and SN2 mechanisms, including reaction conditions, substrate structure, solvent effects, nucleophile strength, carbocation formation and stereochemical changes, and distinguishes substitution from elimination.
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