Download CHEMISTRY 314-01 MIDTERM # 4 April 15, 2003 Name

CHEMISTRY 314-01
MIDTERM # 4
April 15, 2003
Name .....................................................................................
The total number of points in this midterm is 120. The total exam time is 120 min (2 h). Good luck!
1.
2.
3.
4.
(9 pts) Mark as true (T) or false (F) the following statements. Do not explain!
• Fischer esterification occurs only in strongly basic conditions;
• Amides are less reactive than acid chlorides but more reactive than esters;
• Saponification is the process of base-catalyzed hydrolysis of esters;
• Lactones are intramolecular amides;
• Primary amines are molecules in which the amino group is bound to a primary carbon;
• The value of pK b decreases with an increasing strength of the base;
• Primary amines can serve as hydrogen bond donors and hydrogen bond acceptors;
• Secondary amines are stronger bases than primary amines;
• Michael addition reactions give 1,2-addition products;
Circle all that apply:
A. (3 pts) The following reactions CANNOT be used to generate esters:
a. Base-catalyzed reaction of carboxylic acid and alcohol;
b. Reaction of acid chloride and alcohol;
c. Reaction of amide and alcohol;
d. Baeyer-Villiger oxidation of ketones;
B. (3 pts) The following reactions DO NOT occur with an intermediate formation of enolates:
a. Fischer esterification;
b. Claisen condensation;
c. Dieckmann cyclization;
d. Michael addition;
C. (3 pts) The following compounds DO NOT decarboxylate upon heating:
a. β-ketoacids;
b. γ-dicarboxylic acids;
c. β-dicarboxylic acids;
d. γ -hydroxyacids;
(6 pts) Provide an acceptable name for each of the following compounds:
O
NH 2
O
O
O
HO
O
O
HO
OH
O
O
O
OCH 3
N
(5 pts) Provide the structure of each of the following compounds:
(E)-2,3-dimethylbutenedioic acid
2,2-dibromocyclopropanamine
piperidine
5-(dimethylamino)-3-hexynoic acid
4-methyl-2,6-pyridinedicarboxylic acid
5.
6.
7.
(5 pts) Rank the following compounds in order of increasing basicity. Do not explain!
A. Cyclopentylamine;
B. N-methylcyclopentylamine;
C. Aniline;
D. 4-nitroaniline;
E. Sodium amide;
(5 pts) Rank the following compounds in order of increasing acidity. Do not explain!
A. Trichloroacetic acid;
B. Trifluoroacetic acid;
C. Propanoic acid;
D. Isopropanol;
E. Isopropylamine;
Write a complete equation for each of the processes indicated below (NOTE: Do not write mechanisms !!).
A. (4 pts) Reaction of maleic anhydride (cis-butenedioic acid anhydride) with ethanol.
B. (4 pts) Saponification of γ-butyrolactone.
C. (4 pts) Reaction of n-butyl bromide with sodium cyanide, followed by acid hydrolysis;
D. (4 pts) Reaction of ethyl acetate with ethyl formate in the presence of NaOC2H5/C2H5OH;
8.
(18 pts) Predict the principal organic product in each of the following reactions:
1. Mg/ether
Br
2. CO2
3. H3O +
COOH
COOH
O
O
COOH
heat
1. LiAlH4
2. H3O+
1. NaOC2H5/C2H5OH
2.
Br
O
COOH
1. Br2/PBr3
Cl
2. H2O
COOH
CH3
COOC 2H5
COOC 2H5
CH3OH
pyridine
O
1. CH 3MgBr
H2SO 4
2. H3O+
O
1. NaOC2H5/
C2H5OH
O
2.
CH3NH2
1. LDA, H3CO
O
OCH 3
9.
(16 pts) Fill in the blanks in the following scheme:
I
1. NaOCH3/
CH3OH
COOCH 3
COOH
2. H3O
SOCl 2
heat
+
1. NaOCH3/
CH3OH
2. CH3I
N
H
1. NaOH
+
2. H3O ,
heat
10. (6 pts) Propose a mechanis m for the following reaction:
O
C
O
OC2H5
CH3OH
C
OCH 3
+
HCl
C2H5OH
11. Suggest a plausible synthetic sequence for each of the following transformations. Use any necessary organic or inorganic
reagents.
O
O
A. (5 pts)
??
Br
Br
OCH 3
O
Br
B. (5 pts)
??
OC2H5
OC2H5
O
12. Use the acetoacetic or malonic ester synthesis to prepare each of the following compounds. Employ any other necessary organic
or inorganic reagents.
A. (5 pts) 3-ethyl-5-hexen-2-one;
B. (4 pts) Cyclopentanecarboxylic acid;
13. (6 pts) The 1H NMR spectra of two isomeric compounds, A and B, with molecular formula C4H6O2 are shown below. Assign the
correct structure for each isomer.
Compound A
1H
13
12
11
10
9
8
7
6
5
4
3
2
1
Compound B
1H
13
12
11
10
9
8
7
6
5
4
3
2
1
14. (4 pts) BONUS PROBLEM (In order to receive credit for this problem, it has to be solved entirely!!). In the Stobbe condensation
an ester of succinic acid (such as diethyl succinate below) is subjected to base deprotonation and then reacted with a nonenolizable aldehyde or ketone to give a product with a lactone ring. Propose a plausible, detailed mechanism for the Stobbe
condensation below.
O
COOC 2H5
NaOC 2H5
COOC 2H5
C2H5OH
+
Ph
Ph
Ph
Ph
O
COOC 2H5
O