Chem 227 / Exam 2
Practice Questions
1.
How many isomeric ethers are there with the formula of C4H10O?
A.
2
B.
3
C.
4
D.
5
2.
Of the following, which yields isopropyl methyl ether as the major product with little or no by-products?
3.
The role of 18-crown-6 in the reaction shown below is to
A.
B.
C.
D.
4.
complex F¯ by ion-dipole attraction and make it more nucleophilic.
remove Br¯ by ion-dipole attraction and shift the equilibrium to the products.
complex K+ by ion-dipole attraction increasing the solubility of KF and the nucleophilicity of F¯.
stabilize the carbocation in the substitution reaction.
What is the product of the following reaction sequence?
HO
OH
CH 2 CH2
O
BrH 2 CH2 C
HO
C
H
NaC
C
H2 O
H+
OH
CH2 CH2
CH C
CH 2 O
CH 2
OH
C
CH3
Br
CH2
A
C
C
CH3
B
CH2 C
CH2
C
CH C
CH 2
O
O
H 3C C
H+
CH3
C
C
CH3
HC
CH 2 C
CH 2
D
C CH 3
5.
What is the product of the following sequence of reactions?
6.
Identify the most acidic hydrogen on the following molecule.
7.
The pKa of the methylene group of 2,4-pentanedione, CH3-C(=O)-CH2-C(=O)-CH3 is 8.9. Which statement best
describes the charge distribution in the anion formed by deprotonation?
A.
B.
C.
D.
E.
The negative charge is delocalized onto both of the carbonyl oxygens and most of the charge resides on the
two carbonyl oxygens.
The negative charge is delocalized onto both of the carbonyl oxygens and is shared equally by the CH-carbon
and the two carbonyl oxygens.
The negative charge is delocalized onto one of the carbonyl oxygens and is shared equally between the CH
carbon and one carbonyl oxygen.
The negative charge is delocalized onto one of the carbonyl oxygens and most of the charge resides on that
carbonyl oxygen.
The negative charge is localized on the carbon of the central CH group.
8.
Which of the following is the conjugate base of 5-hydroxypentanoic acid?
9.
Which of the following represents the major product from the low temperature reaction of 2-methylcyclopentanone,
LDA (lithium di-isopropylamide) and methyl iodide?
H3 C
O
OH
CH3
A
CH3
CH3
B
O
H3 C
OCH3
CH3
C
CH3
D
10. Acid catalyzed hydrolysis of n-hexyl hexanoate produced a mixture of 1-hexanol and hexanoic acid. When the ether
solution of the mixture was shaken with an aqueous sodium bicarbonate solution, which pair below correctly
describes the distribution in the two resulting immiscible solutions?
11. When 2,6-heptanedione cyclizes in basic solution, which compound is the major product?
O
O
O
CH3
A
CH3
B
CH3
CH2
CH3
C
D
O
12. Which one of the following molecules would be considered as a possible micelle component, and would have the
best stain removing properties?
A.
B.
C.
D.
CH3(CH2)16CO2H
CH3CH2CO2H
CH3(CH2)16CO2Na
CH3CH2CO2Na
13. Starting with 2-bromopropane, select the sequence that produces:
H3C
CH 3
O
(C6H5 )3P
C4H9Li
1
A) 1, 2, 3
2
B) 3, 2, 1
3
C) 3, 1, 2
D) 1, 3, 2
E) 2, 1, 3
14. What products are formed when acetophenone (methylphenyl ketone) is treated with peracetic acid
(CH3COOOH)?
A.
B.
C.
D.
Methyl benzoate + acetic acid
Phenyl acetate + acetic acid
Benzoic acid + acetic acid
Benzyl alcohol + acetic acid + formic acid
15. What is the major product of the following reaction?
O
O
H3C
H
+
OH-
?
100 oC
O
O
H
H3 C
CH3
CH3
H3C
C(CH3 )2
H3C
H
A
H3C
CH3
B
O
H3C
C
O
HO
H3 C
O
CH3
D
E
16. On heating, which –CO2H group in the steroid below would be expected to be lost as CO2?
CO2H
13
HO2C
5
O
A) #2
15 CO2H
2
CO2 H
B) #5
C) #13
17. Which carbon atoms are most susceptible to nucleophilic attack?
A.
B.
C.
D.
E.
I and II
II and III
II and IV
I and IV
III and IV
D) #15
18. What is the missing reagent in the synthesis shown below?
A.
B.
C.
D.
bromocyclopentane
1,4-dibromobutane
1,5-dibromopentane
1,1-dibromocyclopentane
19. Identify the reactants that respectively produce (E)-6-octen-3-ol in the following two reactions.
NaBH4 / OH -
1)
(E)-6-octen-3-ol
2)
CH3
1. MgBr
2. H2 O
O
A
O
CH3
H3 C
H3C
CH3
O
B
O
H3C
CH3
H3 C
CH3
O
C
H3C
H3 C
CH3
H
O
CH3
D H3C
O
H3C
H
O
2
1
20. Select the correct product for the following reaction.
O
O
NaBH 4/OH-
H
CO2 CH 3
OH
O
O
CH2 OH
OH
H
CH 2 OH
CO2CH3
A
B
H
CH 2 OH
C
OH
H
CH2 OH
CH2 OH
CH 3
CO2CH3
CO2CH3
D
E
21. Which of the following shows the correct relative reactivities? (Carefully consider the following
selections.)
A.
B.
C.
D.
E.
acyl chloride < acid anhydride < ester < amide < carboxylate
acyl chloride > acid anhydride > ester > amide > carboxylate
acyl chloride < acid anhydride < ester < carboxylate < amide
acyl chloride > acid anhydride > ester = carboxylate > amide
acyl chloride > acid anhydride > ester > carboxylate > amide
22. Which is the main compound that forms from the acid catalyzed reaction of cylcohexanone and 1,2ethanediol with the removal of water?
HO
OCH2 CH2 OH
HOCH2 CH2 O
A
OCH2CH2 OH
B
HO
OCH2 CH2 O
C
O
O
D
23. When a compound gains electrons, it is being
A.
B.
C.
D.
E.
24.
oxidized.
retro-galvanized.
electrocuted.
electrolyzed.
reduced.
What is the major product of the following addition reaction?
True (A)/False (B)
24. The following reaction produces an enantiomeric excess of (S)-1,2-propanediol.
25. Diisobutylaluminum hydride (DIBAH) will convert ethyl pentanoate to pentanal.
26. An unknown compound, C9H10O2, did not dissolve in aqueous NaOH. The IR spectrum exhibited strong absoption at
1730 cm-1. The 1H-NMR spectrum had signals at d 7.2 (multiplet), d 4.1 (quartet), and d 1.3 (triplet). The compound
is most likely C6H5CH2O-C(=O)CH3.
27. The germinal diol in the tautomerization shown below will most likely be present as more than 50% of the overall
equilibrium concentration.
OH
H3 C C
H
C
O
OH
H3 C C
H2
C
OH
28. The following optically active compound will racemize in dilute KOH/CH3OH solution.
29. Either methyl iodide or methyl triflate can be used in the methylation (alkylation) of an enamine.
30. The following order is correct for increasing pKa values.
CF3COOH > CF3CH2COOH > CCl3COOH
31. Products are favored in the following equilibrium.
O
H 3C
C
O
O–
+
H3C
C
O
C
H2
C
O
O
CH3
H3C
C
O
CH
_
C
O
O
CH 3
+
H3C
C
OH
32. Reacting an alkene with a peracid produces an epoxide.
33. Enolization of 2-methylcyclohexanone can form two different enols. Of the two, 2-Methyl-1-cyclohexen-1-ol is
preferred since it is more stable than 6-methyl-1-cyclohexen-1-ol.
END True/False
34. [6pts] Diethyl malonate and ethyl acetoacetate are versatile starting materials that lead to various important synthetic
intermediates. For the reaction below provide a structure for RX and the product formed prior to the last
hydrolysis/decarboxylation step.
+ CO2
RX=
35. [5pts] Match the choices of the different functions on the left with the four structures. There can be more than one
correct choice for each compound. List all of the correct choices on the right.
A
I:
B
II :
C
III :
D
II
I
IV :
E
III
IV
36. [8pts] E-3-buten-2-one has two electropositive sites where a nucleophile can add. They are indicated below. A
student from a neighboring college ran two reactions, the one below with ethyl Grignard and another one with
lithium diethylcuprate using appropriate reaction work up in both cases. Provide the product for the reaction below.
(Read the entire question first and consider the spectroscopy data before answering.)
A
What is the structure of the product from the reaction with lithium diethylcuprate? Draw its structure.
B
The student not being as well trained as DVC’s Chem 227 students failed to label the two products and ran an IR and an
NMR for one of them which follow. Circle the structure that correlates with the following data: A or B (Circle one.)
1
H NMR: chemical shift; splitting; integration
1.05 ppm (d), (6H)
2.00ppm (m), (1H)
2.10 ppm (s), (3H)
2.30 ppm (d), (2H)
Provide a structure that explains the small amount of a tautomeric equilibrium product in the reaction mixture, which has
the IR peak at ~3500 cm-1.
37. [8pts] Not all reactions are as regioselective as the 1,2- and 1,4 additions- in question #33. The reaction of 2-methyl
cyclohexanone with a strong, non-bulky base and protic solvent will produce two products when reacted with methyl
iodide. One is favored at high temperature and the other at low temperature. Draw the structures of the two products.
Label the reaction coordinate diagram below for the two products. Label the thermodynamic product (T), the kinetic
product (K), the respective enolate intermediates as (IT) and (IK), and all Transition States as (TS).
ΔG
Reaction progress
Complete the mechanism for the formation of both products showing electron movements with arrows, and show how the
intermediate of one can interconvert to the other and be in equilibrium.
CH3 -I
T
IT
CH3 O-H
CH3 OO
H
CH3
H
H
CH3 O-H
CH3 O-
CH3 -I
IK
K