Chem 241 Fall 2008

Chapter 12 Practice Problems Question 1. Provide reagents (by each arrow) that will accomplish the following transformations. Yes, this is mostly from Chapter 10 – but it’s still good practice!

H3C

CH3

O

H3C OH

H3C

CH3

H3C

H3C

H

H3C ClHO

CH3

O

Chem 241 Fall 2008

Question 2. Clearly draw all the π-molecular orbitals for the allyl anion and include orbital phases (a “top view” is OK). Make sure to:

a) Identify all nodes with dotted lines b) Identify the HOMO and the LUMO c) Indicate how many electrons occupy each orbital

allyl anion

Chem 241 Fall 2008

Question 3. Crotonaldehyde (A) is much more stable than methyl ketene (B).

O

H

CH3

O

C

CH3H

A B

a) Draw molecular orbitals, including nodes and orbital phases, for crotonaldehyde. b) Draw the major resonance form(s) of methyl ketene. Are the double bonds in

methyl ketene considered conjugated? Why or why not? c) Explain briefly the difference in stability between A and B.