Questions: Compare the structures of the conjugate acids drawn in parts (a) and (b) of this problem, and determine which is more stable. Based on the stability of the conjugate acids, determine which base, ammonia or DBN, is the stronger base. Explain your choice. - Ammonia is the weaker base because it has the more stable conjugate acid. - DBN is the stronger base because both nitrogen atoms have delocalized lone pairs. - DBN is the stronger base because it has a resonance-stabilized conjugate acid. - Ammonia is the stronger base because it has the more stable conjugate acid.

Solution Steps

The strength of a base is inversely related to the stability of its conjugate acid. A more stable conjugate acid corresponds to a weaker base, while a less stable conjugate acid corresponds to a stronger base. This is because a stable conjugate acid is less likely to donate a proton back to the base, indicating that the base is less eager to accept a proton.

To determine which base is stronger, we need to compare the stability of the conjugate acids of ammonia and DBN (1,5-diazabicyclo[4.3.0]non-5-ene).

• Ammonia's Conjugate Acid: The conjugate acid of ammonia is the ammonium ion (\(\text{NH}_4^+\)). This ion is relatively stable due to its symmetrical tetrahedral structure and the lack of resonance stabilization.

• DBN's Conjugate Acid: The conjugate acid of DBN can be resonance-stabilized. DBN has two nitrogen atoms with lone pairs that can participate in resonance, which can delocalize the positive charge over the structure, increasing its stability.

Since the stability of the conjugate acid is a key factor in determining the strength of the base, we compare the two:

• The conjugate acid of DBN is more stable due to resonance stabilization.
• The conjugate acid of ammonia lacks such stabilization.

Therefore, since DBN has a more stable conjugate acid, it is the stronger base compared to ammonia.

Final Answer