ORGANIC CHEMISTRY
CH 385, Winter 2013
WORKSHOP, Chapter 17
Carbonyl Compounds: Nucleophilic Addition
1. a. Discuss the similarities and differences in the structures and reactivities of the double
bonds of 2-methylpropene and 2-propanone.
b. With part a in mind, account for the following observations. Identify the nucleophile and
the electrophile for the first step of each reaction.
O
H 3C
C
HO
CN
HCN
CH3
C
H 3C
CN
CH3
(fast)
CH2
H 3C
C
CN
HCN
CH3
No Reaction
CH2
HCl
in ether
C
H 3C
CH3
(CH3)3 C–Cl
2. Write detailed electron-pushing mechanisms that explain the stated observations.
a. The following reaction occurs rapidly at pH = 5 but fails at pH = 1.
NHNH2
O
N NH
aq. solution
b. Acetone can be labeled with 18O either acidic or basic solution. The labeling of acetone
with 18O is catalyzed by both acid and base.
O
H3C
C
CH3
H3 18O
H18O
18O
or
H3C
C
CH3
3.
When 2,2-dimethoxypropane is mixed with n-butanol and some p-toluenesulfonic acid in
benzene, the equilibrium shown below is established. The lowest boiling component of
this mixture is methanol. Provide a reasonable mechanism for the reaction and suggest
an experimental technique that could be used to shift the equilibrium to the right and thus
make the reaction useful for synthesizing the dibutylketal. (Note: There is no water
present. Therefore, the reaction does NOT proceed by hydrolysis of the ketal to acetone.)
OCH3
+ 2
OCH3
4.
O
p-TsOH
OH
benzene solvent
O
+
2 CH3OH
Give a reasonable mechanism for each of the following reactions, clearly showing all
important intermediates. Show movement of electron pairs with curved arrows.
OCH3
N
Ph
+ CH 3OH
(excess)
dry HCl
OCH3
+ PhNH3 Cl
O
BrCH2CH2 CH2CH2
1. Ph3P
2. Me3COK
5. Try this and make this ester from the β-ketoaldehyde. Try to shoot for this intermediate.
Show the mechanism to take intermediate A to the product.