Organic Chemistry As a Second Language, 3e: First Semester Topics

Published by John Wiley & Sons
ISBN 10: 111801040X
ISBN 13: 978-1-11801-040-2

Chapter 3 - Acid-Base Reactions - 3.5 Ranking The Four Factors - Problems - Page 68: 3.21

Answer

The proton on the right is more acidic.

Work Step by Step

Draw the conjugate bases: In the first one, I am going to remove the proton on the left: Remove the highlighted hydrogen on the left, and give a lone pair to the nitrogen that was connected to it (It will get a negative charge). In the second one, I am going to remove the proton on the right: Remove the highlighted hydrogen on the right, and give a lone pair to the carbon that was connected to. it (It will get a negative charge). Now, check which one is more stable, use the ARIO rules: 1. Atom: - The first conjugate base has its charge on a nitrogen, and the second one, on a carbon. Therefore, the first base should be more stable. 2. Ressonance: - There are no other structures in both case, so this doesn't make a difference. 3. Induction: - There are no electronegative atoms or excess of carbons next to them. 4. Orbital: - The first conjugate base has its charge on a $sp^3$ hybridized atom, and the seconde one has its charge on a $sp$ hybridized atom. - Therefore, the second conjugate base should be more stable. ** Normally, the first rule is more important than the fourth, but, this is an exception, when the structure has a $sp$ hybridized carbon, and a $sp^3$ nitrogen, the carbon one is more stable. - Since the second conjugate base is more stable, the proton on the right is more acidic.
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.