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CHM 332
Name_______________________________
EXAMINATION - Ch 20 and 21
All answers should be written on the exam in the spaces provided. Clearly
indicate your answers in the spaces provided; if I have to guess as to what or where your
answer is, it is wrong. Where applicable, outline the logic or mystical principle you used
to arrive at your answer, as partial credit may be awarded for correct approaches.
You may assume that standard work-up conditions (i.e. those required to obtain a
stable, neutral product, such as aqueous acid for example) follow each reaction on the
exam. Clearly indicate stereochemistry where appropriate. Be careful not to show
stereochemistry where none exists.
You are strongly advised to read through the entire exam before you begin.
(1)..21 pts....................._____
(2)..15 pts....................._____
(3)..18 pts....................._____
(4)..18 pts....................._____
(5)..10 pts……….……_____
(6)..10 pts……….……_____
(7)..8 pts………...……_____
_______________________
TOTAL (100 pts).........._____
Percentage …………..._____
1. [21 pts] Fill in the necessary reagents or products to complete each of the following
reactions in the formation of 1-phenyl-2-butanol:
A
D
B
C
PBr3
1. NaHCO3
2. CH3I
NaBH4
LiAlH(OtBu)3
G
F
E
OH
DIBAH, -78C
1-phenyl-2-butanol
2. [15 pts] Propose a logical stepwise mechanism for formation of the transesterification
of tert-butyl benzoate to methyl benzoate, using an acid catalyst and methanol solvent.
O
O
O
CH3OH, H+
OCH3
+
HO
3. [21 pts] Indicate the major product that forms in each of the following reactions. You
may assume standard conditions to achieve a neutral stable product.
a.
O
POCl3
NH2
b.
N
LiAlH4
c.
O
mCPBA
d.
O
LAH
H2N
e.
O
O
Cl
OH
f.
O
O
O
O
O
OH
g.
O
O
O
LiAlH4
OH
4.
[18 pts] Synthesis problems - Devise a series of reactions to synthesize the following
molecules. Partial credit will be given for approaches without reagents, if
intermediate structures are shown.
a. [4 pts]
N
OH
b. [6 pts]
O
O
H
N
H
c. [8 pts] Hint: You MUST form a carboxylic acid first!
O
O
Br
O
5. [10 pts] Nomenclature section: Circle the name that is correct for each molecule,
based on IUPAC rules.
i.
O
HO
O
a. 4-keto-5-methylhexan-1-carboxylic acid
b. 4-oxo-5-methylhexanoic acid
c. 5-methyl-4-oxohexanoic acid
d. 3-oxo-4-methylpentanoic acid
ii.
O
O
a.
b.
c.
d.
4-methylheptanoate 4-methylbutanoate
pentyl 4-metylhexanoate
3-methylbutyl 4-methylhexanoate
isobutyl 4-methylhexanoate
iii.
O
OH
H3CHN
a.
b.
c.
d.
5-hydroxy-1-methylaminohexanone
5-hydroxy-1-methylhexanamine
N,5-hydroxymethylhexanamide
5-hydroxy-N-methylhexanamide
iv.
Cl
O
Br
a. 4,4-dimethyl-3-chlorohexanoyl bromide
b. 1-bromo- 4,4-dimethylhexanoyl-3-chloride
c. 3-chloro-4,4-dimethylhexanoyl bromide
d. 1-bromo-3-chloro-4,4-dimethyl-1-hexanone.
v.
O
O
O
a. sec-butanoic propanoic anhydride
b. ethanoic sec-butanoic anhydride
c. acetic isopropanoic anhydride
d. isobutanoic propanoic anhydride
6. [10 pts] Identify the functional groups that form in each of the following reactions:
a. addition of a Grignard reagent to a nitrile
_________________________
b. addition of LAH to an amide
_________________________
c. addition of (CH3)2CuLi to an acid chloride
_________________________
d. addition of CH2N2 to a carboxylic acid
_________________________
e. addition of aqueous acid to an acid anhydride
_________________________
7. [16 pts] Thought Provoking Questions (a.k.a. Short Answers): Choose 4 of the 6
following questions.
a. Give two reasons why DIBAH reduces esters to aldehydes and not alcohols.
b. Experiments show that the molecular weight of acetic acid in the vapor state is
approximately 120. Explain the discrepancy between this experimental value and the
true value of approximately 60.
c. Explain why the addition of water to an amide to form a carboxylic acid is not catalytic
in acid, unlike a reaction such as the Fischer esterification.
O
H2O, H+
NH2
O
OH
+
NH3
d. Explain the two factors that make a carboxylic acid, such as benzoic acid, acidic.