Chapter 25q: Chapter Quiz

Last updated
Save as PDF

Page ID: 211738

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

Amines Chapter Quiz

Exercise \(\PageIndex{1}\)

Which molecule in each of the following pairs of amines is more basic? Explain why.

25 1a.png

25 1b.png

25 1c.png

Answer

25 1a answer.png

Ethanamine is a stronger base because it's lone pair of electrons is available to react. In aniline, the electron pair is partially tied up in resonance and less available.

25 1b answer.png

Pyridine is a stronger base because it's lone pair of electrons is available to react. The electron pair cannot be involved in the ring resonance since it is in an sp² hybrid orbital that is perpendicular to the ring. In aniline, the electron pair is partially tied up in resonance and less available.

25 1c answer.png

Pyrrolidine is a stronger base because it's lone pair of electrons is available to react. The lone pair of electrons on pyrrole will be in a p-orbital. This will make the molecule aromatic (6 pi electrons in the ring). If these electrons acted as a base to make a new bond to H, the molecule would lose aromaticity.

Exercise \(\PageIndex{2}\)

Show using resonance structures why amines are much more basic than amides.

Answer

25 quiz 2 answer.png

In amides, the nitrogen lone pair is delocalized with partial double bond character, therefore it is less available to react than in an amine.

Contributors

Layne Morsch (University of Illinois Springfield)