Practice Hour Exam 2, Chemistry 2210, Organic Chemistry I
1. The most stable carbocation is:
2. Which of the following statements is true of transition states?
A.
A transition state represents a minimum on the reaction path diagram and can be isolated.
B.
A transition state represents a maximum on the reaction path diagram and can be isolated.
C.
A transition state represents a minimum on the reaction path diagram and cannot be
isolated.
D.
A transition state represents a maximum on the reaction path diagram and cannot be
isolated.
3. Which of the following structures is the least stable conformation of butane?
4. Which of the following compounds is/are meso?
I
A. I only
B. II only
IV
III
II
C. III only
D. II and III
5. Which of the following compounds would react the fastest in an SN1 reaction?
A. (C6H5)3CCl
B. (C6H5)3CCH2Cl
C. (C6H5)2CHCl
D. (CH3)3CCl
6. What is the IUPAC name of the following compound?
A. 4-bromo-4-ethyl-2,5-dimethyloctane
B. 5-bromo-4-ethyl-2,4-dimethyloctane
C. 4-bromo-3-isobutyl-3-methylheptane
D. 3-bromo-3-ethyl-5-methyl-2-propylhexane
7. The most stable conformation of the following compound has the methyl group in the ______
position and the tert-butyl group in the __________ position.
A. Equatorial, Axial
B. Equatorial, Equatorial
C. Axial, Axial
8. What is the relationship of the following compounds?
OH
CH2CH3
H
OH
CH3CH2
H
OH
CH3
CH3
A. Enantiomers
C. Constitutional isomers
H
OH
H
B. Diastereomers
D. Same compound
D. Axial, Equatorial
9. Which statement is true for the reaction shown here?
NaOH + CH3CO2H → H2O + CH3CO2Na
A. NaOH is the base and CH3CO2Na is its conjugate base
B. NaOH is the acid and H2O is its conjugate base
C. CH3CO2H is the acid and CH3CO2Na is its conjugate base
D. CH3CO2H is the base and CH3CO2Na is its conjugate acid
10. Which of the following changes will increase the rate of the following reaction?
Br
+
SH +
SH
Br
I. Replace ‒SH with H2S
II. Replace (CH3)2CHCH2Br with CH3CH2CHBrCH3
III. Replace (CH3)2CHCH2Br with (CH3)2CHCH2OH
IV. Use the solvent DMSO instead of methanol
A. I and III
B. II
C. I and IV
D. IV
11. What is the energy of activation for the reaction of B → C?
kJ/mol
35
30
25
C
Series1
20
A
15
10
B
5
reaction coordinate
A. 6 kJ/mol
B. 3 kJ/mol
C. 9 kJ/mol
D. 23 kJ/mol
12. Which of the following statements correctly describes the molecule shown below:
A. It is achiral
B. It is meso
C. Its chirality center possesses the R configuration
D. The mirror image of this molecule is its enantiomer
13. For the following reaction step, indicate the mechanistic pattern.
A. Proton Transfer
B. Loss of Leaving Group
C. Nucleophilic Attack
D. Rearrangement
14. Which of the following is/are the most likely product(s) for the following reaction?
Br
KCN
acetone
CN
CN
A.
C.
and
CN
CN
B.
D.
CN
15. What is the IUPAC name of:
HH
I
A. trans-1-iodo-2-vinylcyclohexane
C. trans-2-iodo1-vinylcyclohexane
B. cis-1-iodo-2-vinylcyclohexane
D. cis-2-iodo-1-vinylcyclohexane
16. What is the configuration of the following molecule?
H
H
C2
C3
HO
A.
(2R,3R)
B.
(2S,3S)
CH3
COOH
CH3
C.
(2R,3S)
D.
(2S,3R)
17. What is wrong with the following mechanism?
A. There is no leaving group, so there should be no arrows.
B. The arrow should be removing a proton from the H2O group.
C. An arrow is also needed to indicate the loss of the leaving group.
D. The arrow indicating the formation of the C-Br bond (nucleophilic attack) should start at the
bromide anion.
18. What is the product of the following SN1 reaction?
19. What is the relationship between the following two molecules?
A. diastereomers
C. enantiomers
B. conformers
D. constitutional isomers
20. Which of the following compounds has the lowest boiling point?
21. Give the IUPAC name for the following compound.
A. (S)-2-methyl-4-chloro-1-hexene
C. (S)-2-methyl-4-chloro-1-pentene
B. (R)-2-methyl-4-chloro-1-hexene
D. (R)-2-methy-4-chloro-1-pentene
22. The major compound that will form in the following SN1 reaction will be:
23. Your sample of Compound-X was found to have a specific rotation of +20°. A sample of
pure Compound-X has a specific rotation of +100°. What is the composition of the sample?
A. 20% (+) isomer and 80% (-) isomer
B. 80% (+) isomer and 20% (-) isomer
C. 60% (+) isomer and 40% (-) isomer
D. 40% (+) isomer and 60% (-) isomer
24. Which of these statements is false?
A. Angle strain is a major problem in cyclopropane.
B. Gauche butane has torsional strain.
C. Boat cyclohexane is destabilized with respect to chair cyclohexane, partly due to flagpole
steric strain.
D. On a cyclohexane, 1,3-diaxial interactions are an example of steric strain.
25. What is the correct priority of these groups with respect to (R,S) determination in
stereochemistry, with highest priority group first? Assume these groups are all bonded to the
same chirality center.
A. -CH2CH2F > -CH2OH > -CH=CH2 > -C(CH3)3
B. -CH2OH > -C(CH3)3 > -CH=CH2 > -CH2CH2F
C. -CH2OH > -C(CH3)3 > -CH2CH2F > -CH=CH2
D. -C(CH3)3 > -CH=CH2 > -CH2OH > -CH2CH2F