Rank the labeled protons (H_a-H_d) in order of increasing acidity, starting with the least acidic.

Question

Quizplus · Accepted Answer

The trend of increasing acidity is determined by the stability of the conjugate base that is formed after the proton is removed. The more stable the conjugate base, the more acidic the proton. In this case, the conjugate bases are: - H_a- (conjugate base of Ha) - H_b- (conjugate base of Hb) - H_c- (conjugate base of Hc) - H_d- (conjugate base of Hd) The conjugate base of Ha is the least stable because it has a negative charge on the oxygen atom, which is not as stable as a negative charge on a nitrogen atom (as in Hb, Hc, and Hd). Therefore, Ha is the least acidic. The conjugate bases of Hb, Hc, and Hd all have a negative charge on the nitrogen atom, but the conjugate base of Hd is the most stable because it has a resonance structure that spreads the negative charge over two nitrogen atoms. Therefore, Hd is the most acidic and Hb is the least acidic. Therefore, the correct order of increasing acidity is: Hb < Hc < Ha < Hd.

Rank the Labeled Protons (Ha-Hd) in Order of Increasing Acidity

Rank the Labeled Protons (H_a-H_d) in Order of Increasing Acidity