Chapter 4 1. What is the IUPAC name for the following compound?
A) B) C) Ans:
7,7 diethyl-5-isopropyl-3,4-dimethyldecane diethyl-5-isoprop yl-3,4-dimethyldecane 7,7-diethyl-5-isopropyl-2,3-dimethyldecane 7,7-diethyl-4-isopropyl-2,3-dimethyldecane B
2. Give the IUPAC name for the following compound.
A) 7,7-diethyl-2,4,5-trimeth 7,7-diethyl-2,4 ,5-trimethylnonane ylnonane B) 7-ethyl-2,4,5-trimethyloctane Ans: A
C)
6-ethyl-2,4,5-trimethyloct 6-ethyl-2,4,5- trimethyloctane ane
3. Give the IUPAC name for the following compound.
A) 4,4-diethyl-2,3,6-trimeth 4,4-diethyl-2,3 ,6-trimethylnonane ylnonane B) 5,5-diethyl-4,7,8-trimethylnonane Ans: C
C)
5,5-diethyl-2,3,6-trimethyln 5,5-diethyl-2,3, 6-trimethylnonane onane
4. Give the IUPAC name for the following compound.
A) 2,5-dimethyl-3- t -butylheptane -butylheptane B) 2,5-dimethyl-4- t -butylhexane -butylhexane Ans: C
C)
Page 1
2,5-dimethyl-4- t -butylheptane -butylheptane
5. Give the IUPAC name for the following compound.
A) 7-ethyl-6-isobutyl-3-methylundecane C) B) 7-ethyl-6-isobutyl-3-methylnonane Ans: C
7-ethyl-6-isobutyl-3-methyldecane
6. Give the IUPAC name for the following compound.
A) 5-sec-butyl-2,4-dimethylnonane B) 6-sec-butyl-2,4-dimethyldecane Ans: C
C)
6- sec-butyl-3,5-dimethyldecane
7. Give the IUPAC name for the following compound. H H3C
CH3
H H
A) 2-methyl-4-isopropylheptane B) 2-methyl-4-isopropyloctane Ans: A
C)
3-methyl-5-isopropylhexane
8. Give the IUPAC name for the following compound.
A) B) C) Ans:
1-sec-butyl-4-isopropyl-2-methylcycloheptane 1-sec-butyl-4-isopropyl-2-methylcyclohexane 1-sec-butyl-3-isopropyl-3-methylcyclohexane B
Page 2
9. Give the IUPAC name for the following compound. H H H
A) 4-ethyl-5-isopropylnonane B) 5-ethyl-4-isopropyloctane Ans: C
C)
5-ethyl-4-isopropylnonane
10. Give the IUPAC name for the following compound.
A) B) C) Ans:
5-sec-butyl-7,7-diethyl-2,3-dimethyldecane 4-sec-butyl-6,6-diethyl-2,3-dimethyldecane 5-sec-butyl-7,7-diethyl-2,3-dimethylundedecane A
11. Give the IUPAC name for the following compound.
A) B) C) Ans:
6-isobutyl-3,7-dimethyl-7-propyluncedecane 4-isobutyl-2,5-dimethyl-5-propylnonane 5-isobutyl-2,6-dimethyl-6-propyldecane C
12. Give the IUPAC name for the following compound.
A) 4-isobutylyl-2-methylhexane B) 4-isopropyl-3-methylheptane Ans: B
C)
Page 3
4-isopropyl-2-methylheptane
13. Give the IUPAC name for the following compound.
A) 5,5-diethyl-2,3,6-trimethyldecane B) 5,5-diethyl-2,3,6-trimethylnonane Ans: B
C)
4,4-diethyl-2,3,6-trimethylnonane
14. Give the IUPAC name for the following compound.
A) 3,6-diethyl-4,4,5-trimethylnonane B) 2,5-diethyl-3,3,4-trimethylnonane Ans: A
C)
2,5-diethyl-3,3,4-trimethyloctane
15. The preferred conformation of cis-3-t -butyl-1-methyl-cyclohexane is one in which: A) the t -butyl group is axial and the methyl is equatorial. B) the methyl group is axial and the t -butyl group is equatorial. C) both groups are axial. D) both groups are equatorial. E) None of the choices are correct. Ans: D 16. Which represents the ring-flipped conformer of a?
A) A Ans: D
B) B
C) C
D) D
E) E
Page 4
17. Consider the molecule cis-1-ethyl-3-isopropylcyclohexane. Which is the overall most-stable conformer?
A) A Ans: C
B) B
C) C
D) D
E) E
18. Which of the following structures represents the most stable form of 1-isopropyl-2-methylcyclohexane?
A) A Ans: D
B) B
C) C
D) D
E) E
Page 5
19. Select the most stable conformer of cis-1, 3-cyclohexane diol.
A) A Ans: B
B) B
C) C
D) D
E) E
20. Rank the indicated conformations in order of decreasing stability.
A) A
B) B
C) C
21. Which conformation is the most stable?
A) A Ans: C
B) B
C) C
Page 6
D) A
E) C
22. Which of the following conformations of 1,2-dibromoethane is the most stable? H
H Br
H H
Br
Br
Br
A
B
C) C
H H
H Br
H H
B) B
Br
Br
Br
H
H
A) A Ans: B
H
H H
H H
C
D
D) D
23. Given the three Newman projections drawn below, rank them in order of increasing stability.
A) B
B) C
C) C
D) B
E) A
24. Rank the following conformations in order of increasing energy.
A) C < B < A B Ans: A
B) B < A < C
C) B < C < A
Page 7
D) A < B < C
E) C < A <
25. Assuming that the size of substituents is H
CH3 A
H3 C
I
H
B H
H H
H H3 C
A) A Ans: C
CH3 H
I
I
H
E
H H
H
H CH3
B) B
C) C
D) D
E) E
26. Which of the following two conformers is higher in energy?
A) A Ans: B
C
CH3 CH3
H
H I
CH3
I CH3 D
H
B) B
Page 8
27. The graph below shows the energy changes that occur during rotation around the C–C bond indicated in compound a. Which letter(s) on the graph correspond(s) to this Newman Projection?
A) A and G Ans: D
B) B and F
C) C and E
D) D
28. Consider rotation about the indicated bond in the molecule below. Which Newman Projection best represents the most stable conformer of the molecule during rotation about the indicated bond?
A) A Ans: A
B) B
C) C
Page 9
29. Which statement about the following conformers of the same compound is true?
A) B) C) D) E) Ans:
B is the most stable and A is the most stable and C is the most stable and B is the most stable and A is the most stable and E
A is the least stable. B is the least stable. A is the least stable. C is the least stable. C is the least stable.
30. How are the molecules below related to each other?
A) B) C) D) E) Ans:
They are constitutional isomers. They are identical. They are resonance structures. They are not isomers; they are different compounds. They are stereoisomers. C
31. How are the molecules below related to each other?
A) B) C) D) E) Ans:
They are constitutional isomers. They are identical. They are resonance structures. They are not isomers; they are different compounds. They are stereoisomers. A
Page 10
32. How are the molecules below related to each other?
A) B) C) D) E) Ans:
They are constitutional isomers. They are identical. They are resonance structures. They are not isomers; they are different compounds. They are stereoisomers. B
33. How are the molecules below related to each other?
A) B) C) D) E) Ans:
They are constitutional isomers. They are identical. They are resonance structures. They are not isomers; they are different compounds. They are stereoisomers. A
34. How are the molecules below related to each other?
A) B) C) D) E) Ans:
They are constitutional isomers. They are identical. They are resonance structures. They are not isomers; they are different compounds. They are stereoisomers. D
Page 11
35. How are the molecules below related to each other?
A) B) C) D) E) Ans:
They are constitutional isomers. They are identical. They are resonance structures. They are not isomers; they are different compounds. They are stereoisomers. C
36. Which of the following statements is (are) true about the following compound?
A) B) C) D) E) Ans:
Ca and Cd are 1° carbons. Cb and Cc are 3° carbons. Ce and Ca are 2° carbons. (Ca and Cd are 1° carbons) and (C b and Cc are 3° carbons). (Cb and Cc are 3° carbons) and (C e and Ca are 2° carbons). E
37. Which of the following statements is (are) true about compound B below? Ca
Cc Cb B
A) B) C) D) E) Ans:
Ca and Cb are quaternary. Cc is primary. Ca is quaternary. Cb is tertiary. Cc is primary, C a is quaternary, and C b is tertiary. E
Page 12
38. Predict the most stable conformation of cis-1-isopropyl-4-ethylcyclohexane. A) The isopropyl group is axial and the ethyl group is equatorial. B) Both groups are axial. C) Both groups are equatorial. D) The isopropyl group is equatorial and the ethyl group is axial. E) There is no way to predict for this molecule. Ans: D 39. Which of the following equations is correct for the combustion of cyclohexane? A) B) C) D) E) Ans: B 40. What is the relative position of the substituents A and B to each other in the following conformation?
A) Anti Ans: D
B) Eclipsed
C) Syn
D) Gauche
41. Which of the following Newman projections represents the most stable conformation of 2,3-dimethylbutane? H
CH3 CH3
H3C H3C
H
H
H
CH3
B) B
C) C
CH3 CH3
B
C
D) D
Page 13
CH3 H
H3C
CH3
A
A) A Ans: C
CH3
H
CH3
CH3
H
H H3C
CH3 CH3
D
42. Which of the following statements best explains the reason for the relative stabilities of the two conformers shown below? CH3 CH3
H H
H3C CH3
H CH3
A.
A) B) C) D) E) Ans:
H H
H H3C
B.
A has more torsional strain; B has more steric strain. A has more steric strain; B has more torsional strain. A and B have the same torsional strain. A and B have the same steric strain. A and B have similar steric strain; B has more torsional strain. E
Challenge Questions
43. Give the IUPAC name for the following compound. H H
H
H H
A) B) C) D) E) Ans:
H
4-isobutyl-2-ethyl-1-isopropylcyclohexane 4-sec-butyl-2-ethyl-1-isopropylsyclobutane 4-sec-butyl-2-ethyl-1-isopropylcyclohexane 2-ethyl-4-isobutyl-1-isopropylcyclohexane 1-isopropyl-2-ethyl-4-secbutylcyclobutane C
44. Which of the following cyclohexane derivatives is most stable?
A
A) A Ans: A
B
B) B
C) C
C
D) D
Page 14
D
45. (3Z)-Dactomeleyne has been isolated from the digestive glands of the sea hare Aplysia dactylomela. In the 1995 synthesis by E. Lee and co-workers, the compound below undergoes a reduction reaction to produce one of the late stage intermediates. Identify a possible product from this reaction.
Cl
O
CO2CH3
O
?
Br
OH
Cl
O
Cl
COCl
O
O
Br
Cl
CO2CH3
O
O
Br
O
OH
A
O
B) B
Cl
OH
O
OH
C) C
O
Br
Br
OH
B
A) A Ans: D
CO2CH3
C
D
D) D
46. Cryptophycin C is a marine natural product with anti-cancer activity. An intermediate in its synthesis is shown below. Identify the most stable Newman projection looking down the C2-C3 bond. HO
O 1 2
O
3
5
O NHBoc
4
(intermediate for Cryptophycin C)
HO
O
HO
H
O
H H
O
HO
H
H
H
O
H
O
BocHN
H
O H
A
A) A Ans: A
B) B
H
O
H BocHN
O
B
C) C
Page 15
BocHN
O H
C
47. How is each molecule (i-iv) related to compound A? OH OMe O
MeO
OH NH2
Compound A OH
OH
OMe
OMe OMe HO
OMe O
OMe
MeO
NH2
O
MeO
i
ii
O
OH
OH
NH2
A) B) C) D) Ans:
OH
O
H
NH2
HO MeO
iii
i) Constitutional isomer, ii) stereoisomer, iii) identical, iv) stereoisomer i) Stereoisomer, ii) constitutional isomer, iii) identical, iv) stereoisomer i) identical, ii) constitutional isomer, iii) identical, iv) stereoisomer i) stereoisomer, ii) identical, iii) constitutional isomer, iv) identical C
Page 16
O
iv
H
NH2
