Question Detail

CHM 102 Alkynes: Structure, Bonding, and Nomenclature Objective Question

Question

Which base is strong enough to deprotonate a terminal alkyne (pKa ≈ 25)?
Options
A NaOH (pKa of H₂O = 15.7)
B NaHCO₃ (pKa of H₂CO₃ = 6.4)
C NaNH₂ (pKa of NH₃ ≈ 38)
Correct Answer
D CH₃COONa (pKa of CH₃COOH = 4.76)
Correct Answer

Option C is the correct answer.

Detailed Explanation

Sodium amide (NaNH₂) has a conjugate acid (NH₃) with pKa ≈ 38, which is higher than 25, so it can deprotonate terminal alkynes. NaOH cannot.

Hint

A base can deprotonate an acid if its conjugate acid has a higher pKa.

Question Info