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CHM238-01 S04 Exam 3 April 2, 2004 109 points 1. (6 pts) Name the following compounds: Use R or S where appropriate.
O
CH3
CH3
O
O
H
CH3
H
CH3
2 (6 pts) Draw the following compounds from the names given: (2R, 3S)-2,3-butene oxide m-Chloroperbenzoic Acid 2-oxypropanoic acid 3 (22 pts) Draw arrows and necessary lone pairs to demonstrate the proper mechanism for the formation of the product of the reaction of dimethyl amine and acetaldehyde..
CH3
NHCH3
CH3 H
OCH3
O-
N+
H
CH3CH3
H
S:CH3
O-
N
H
CH3CH3
S
H
CH3
OH
N
H
CH3CH3
+
CH3
OH2+
N
H
CH3CH3
+S
S
HS
H
N+
H
CH3CH3
H
+ H2O
CH2
N
H
CH3CH3
key intermediate product
(a) What is the functional group of the product called? (b) What is the name of the functional group of the key intermediate? (c) Protons are exchanged in this reaction. Very weak acid is OK ~ pH= 6.5. Why would this reaction not work in strong acid -- pH < 2? Draw a structure that represents what happens to the nucleophile. (d) The reaction as written would not occur if the amine reacted were methyl amine (CH3NH2) --not dimethyl amine. What would the product of that reaction be under the same conditions as above? (e) This reaction is reversible. How would you turn the final product back into dimethyl amine and acetaldehyde?
4. (16 pts) These reactions all have some apparent contradictions. Provide reasoning for the results. (a) In the Wolff-Kishner reaction below, only one carbonyl is reduced. Explain why:
NH
O
O
NH2 NH2KOH
diethyleneglycol 150 C
NH
O
(b) Attempts to make salicylic acid by grignard reaction with CO2 largely fail. Why?
Br
OH
Mg
Et2O
MgBr
OH
1. CO2
OH
OH
O
2. Acid Workup
(c) In the Williamson ether synthesis, the ether is prepared by reaction with alkoxide nucleophile and and a bromide electrophile. Why can phenyl ethyl ether (phenetole) not be synthesized this way, but p-nitrophenetole can be?
O CH3Br
CH3
O-+
O CH3
N+
O-
O
Br
N+
O-
O
CH3
O-+
(d) The following keto-aldehyde compound has one of its carbonyls preferentially protected in the presence of one mole of ethylene glycol and acid catalyst. Draw the acetal product and explain.
O
H
O
CH3
OH OH
p-tolylsulfonic acid
Draw main product
5. (36 pts) Identify products and reagents that will accomplish the following organic transformations. Put structures of reagents in the blanks indicating steps in the reactions below. Below is a version of the industrial synthesis of glycerin (1,2,3-propanetriol):
CH2
CH3A
CH2
BrNaOH
H2OB
C O
OH
D OH OH OH
glycerin A B C D
1. Ph3P
2. BuLi
CH3
CH3
BrCH3 AB
C
C
N
N
D
O
O
OH
OH
1. E
2. Me2SO
OHH
O
O
Wittig Reagent
CCH3 CH3
A B C D E The synthesis of Ibuprofen from the Boot Pure Drug Company::
CH3
CH3
CH3
OCH3
CH3
A
CH3
CH3
CH3
O
H2 steps--not shown
B
CH3
CH3
N
HCH3
OH
dehydrate
CH3
CH3
CN
CH3
-H2O
C
CH3
CH3
CCH3
O
OH
AlCl3
A B C
6. (18 pts) Pick 3 out of the 9 reagents and put them in the correct order to accomplish these reactions..
(a)
1
2
3
O
ClCH3
Hint: Consider reduction. a. H2N-NH2, KOH, heat b. CH3MgBr, ether c. (CH3)2CuLi + acid wkup d. PCC e. CH3Br f. POCl3 g. NaH h. 1. LAH 2. Acid Wkup i. 1. BH3-THF 2. H2O2, OH-
(b)
1
2
3
CH3OH
Hint: Consider oxidation. a. H2N-NH2, KOH, heat b. CH3MgBr, ether c. (CH3)2CuLi + acid wkup d. PCC e. Ag2O (aq) f. HBr, heat g. NaH h. CH3Br i. 1. BH3-THF 2. H2O2, OH-
(c)
1
2
3
OH
HOH
O
CH3
Hint: Consider oxidation. a. H2N-NH2, KOH, heat b. CH3MgBr, ether c. (CH3)2CuLi + acid wkup d. PCC e. Ag2O (aq) f. POCl3 g. 1. LAH 2. Acid Wkup h. CH3Br i. 1. BH3-THF 2. H2O2, OH-
7. (5 pts) Rank the acids below: 1 strongest to 4 weakest: If a diacid, consider only the first ionization.
OO
OHOH
O
OH
O
OH
O
OH
O
OH
CH3
O
OH
acetic acid succinic acid oxalic acidmalonic acid
Name:
Points from Page 1 out of 34 points. Page 2 out of 16 points. Page 3 out of 36 points. Page 4 out of 23 points. Total 109 points Total Points out of 100 points.
