Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
Chapter 1: Structure Determines Properties
1. What is the ground state electron configuration of carbon?
A) 1s22s22px1 B) 1s22s22px2 C) 1s22s22px12py1 D) 1s22s22px22py1
Ans: C
2. Which of the following has (have) the same electron configuration as Ne?
Na- Mg2+ O2- Mg+
A) Na- and O2- B) Mg2+ and O2Ans: B
C) Mg+ and O2-
D) only Mg2+
3. What is the letter designation given to dumbbell shaped orbitals like the one depicted
below?
A) s B) p
Ans: B
C) d
D) f
4. What is the charge on the phosphorus ion in Na3P?
A) -3 B) -1 C) +1 D) +3
Ans: A
5. Predict which bond is the most polar in ethanol, CH3CH2OH?
A) C—C B) C—H C) C—O D) O—H
Ans: D
6. Which one of the following is the conjugate base of NH3?
A) NH4+ B) H+ C) N3- D) NH2–
Ans: D
7. Which one of the following is the ionic compound formed between magnesium and
chlorine?
A) MgCl B) MgCl2 C) Mg2Cl3 D) MgCl3
Ans: B
Page 1
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
8. Identify the condensed formula of the following structure:
A) (CH3)2CHCHClCH(CH3)2
B) CH3CH(CH3)CHClCH(CH3)2
Ans: C
C)
D)
(CH3)2CHCHClC(CH3)3
(CH3)3CCHClCH(CH3)3
9. What is the chemical formula of the following carbon skeleton diagram?
A) C8H14
Ans: C
B) C8H16
C) C8H18
D) C8H20
10. How many hydrogen atoms are there on carbon atoms 1 and 2, respectively, in the
structure below?
A) 4, 1 B) 4, 0
Ans: D
C) 3, 1
D) 3, 0
11. How many C3H8O constitutional isomers are possible?
A) one B) two C) three D) four
Ans: C
Page 2
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
12. Which of the following best describes the relationship between the following two
structures?
A)
B)
C)
D)
Ans:
identical compounds
resonance structures
constitutional isomers
different compounds with different constitutions
A
13. How many constitutional isomers of C4H9Br are possible?
A) one B) two C) three D) four
Ans: D
14. How many constitutional isomers of C3H6Cl2 are possible?
A) three B) four C) five D) six
Ans: B
15. What is the formal charge on the carbon atom?
A) +1 B) 0
Ans: C
C) -1
D) -2
Page 3
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
16. Which of the following describes the relationship between the following two structures?
A)
B)
C)
D)
Ans:
identical structures
resonance forms
constitutional isomers
different compounds with different compositions
A
17. Which of the following describes the relationship between the following two structures?
A)
B)
C)
D)
Ans:
identical structures
resonance forms
constitutional isomers
different compounds with different compositions
B
18. What is the formal charge on the oxygen atom in the structure below?
A) -1 B) 0
Ans: C
C) +1
D) +2
19. What is the formal charge on the nitrogen atom in the structure below?
A) -1 B) 0
Ans: C
C) +1
D) +2
Page 4
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
20. The formal charges on the nitrogen and oxygen in the following structures are,
respectively
A) +1, -1
Ans: B
B) 0, -1
C) +1, 0
D) 0, 0
21. In which of the following compounds would you expect Cl to have a partial positive
charge?
A) HCl B) CCl4 C) NaCl D) HOCl
Ans: D
22. Based on the VSEPR model, which of the following species has (have) a trigonal planar
geometry?
I. BCl3 II. NH3 III. NO3¯
A) only I B) I and II C) I and III D) I, II, and III
Ans: C
23. Based on VSEPR theory, which of the following species has (have) a trigonal pyramidal
geometry?
I. CO32- II. NH3 III. CH3+
A) only I B) only II C) I and II D) II and III
Ans: B
24. Which of the following species has(have) a linear geometry?
I. CO2 II. NO2+ III. NO2¯
A) only I B) only II C) I and II D) I, II, and III
Ans: C
25. Which of the following molecules would you expect to have a dipole moment?
I. CO2 II. HCN III. CHCl3
A) II and III B) only II C) only III D) I, II, and III
Ans: A
26. Which of the following molecules would you expect to have a dipole moment?
I. CH2Cl2 II. CH3Cl III. CCl4
A) only I B) only II C) I and II D) I, II, and III
Ans: C
27. The H—C—H bond angles in ethylene, C2H4, are closest to
A) 90o B) 109.5o C) 120o D) 180o
Ans: C
Page 5
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
28. The C—C—C bond angle in propane, C3H8, is closest to
A) 90o B) 109.5o C) 120o D) 180o
Ans: B
29. The C—C—C bond angle in propyne, shown below, is
A) 90o B) 109.5o
Ans: D
C) 120o
D) 180o
30. The hybridization of carbon atoms 1, 2, and 3 in the following are, respectively
A) sp, sp, and sp2
B) sp, sp, and sp3
Ans: C
C)
D)
sp2, sp2, and sp3
sp2, sp3, and sp3
31. How many pi bonds are present in the following structure?
A) one B) two
Ans: C
C) three
D) four
32. The carbon-carbon single bond in the following is formed by the overlap of which two
orbitals?
A) sp-sp
Ans: B
B) sp2-sp
C) sp2-sp2
D) sp2-sp3
33. What are the formal charges of boron and nitrogen, respectively, in the following
structure?
A) -1 and +1
Ans: A
B) -1 and 0
C) 0 and +1
D) 0 and 0
Page 6
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
34. Which one of the following is isoelectronic with CO2?
A) NO2¯ B) NO2+ C) NO2 D) O3
Ans: B
35. In which of the following does hydrogen have a partial negative charge based on
electronegativity?
A) BH3 B) CH4 C) NH3 D) H2O
Ans: A
36. Which of the following species have a zero formal charge on its carbon atom?
A) I and II
Ans: B
B) II and IV
C) III and IV
D) I, II, and III
37. Which one of the following species is formed when diazomethane loses a nitrogen
molecule?
diazomethane
A) A B) B C) C D) D
Ans: A
Page 7
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
38. Which species is formed when the CH3N2+ cation loses a nitrogen molecule?
A. H3C
B. H2C
C. H3C •
D. H3C
A) A B) B C) C D) D
Ans: A
39. Give the molecular formula of the compound shown below:
A) C8H16O
Ans: D
B) C9H18O
C) C10H18O
D) C10H20O
40. The electron pair movement depicted below produces a second resonance form for the
species. What is the formal charge on the nitrogen atom for this second resonance form?
A) -2 B) -1
Ans: B
C) 0
D) +1
41. Which statement correctly describes the structures of BH3 and NH3?
A) Both are trigonal and planar.
B) Both are pyramidal.
C) BH3 is trigonal planar and NH3 is trigonal pyramidal.
D) BH3 is trigonal pyramidal and NH3 is trigonal planar.
Ans: C
Page 8
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
42. Which one of the following is the conjugate acid of ethanol?
A) CH3CH2O– B) CH3CH2O+ C) CH3CH2OH2+ D) CH3CH2OH3+
Ans: C
43. In the equilibrium below, the strongest base is:
(pKa H2O = 15.7, pKa NH3 = 36)
A) A B) B C) C D) D
Ans: B
44. In the equilibrium below, the strongest acid is:
A) A B) B C) C D) D
Ans: A
Page 9
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
45. Which one of the following is the strongest base?
A) A B) B C) C D) D
Ans: A
46. Which one of the following mechanistically depicts the protonation of methanol by
hydrogen bromide?
A) A B) B C) C D) D
Ans: A
Page 10
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
47. Which one of the following is the strongest acid?
A) FCH2CO2H B) ClCH2CO2H C) BrCH2CO2H
Ans: A
Prof. Sivaguru Jayaraman
D) ICH2CO2H
48. Which one of the following has the largest acid equilibrium constant, Ka?
A) CH3CO2H B) CH2ClCO2H C) CHCl2CO2H D) CCl3CO2H
Ans: D
49. For which of the following does the equilibrium favor reactants.
A) A B) B C) C D) D
Ans: C
50. Identify the resonance structure which results from the following "electron pair
movements".
A) A B) B C) C D) D
Ans: A
Page 11
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
51. A Lewis structure of the azide ion, N3¯, is shown below. The formal charge on the
middle nitrogen atom is:
A) +2 B) +1
Ans: B
C) 0
D) –1
52. Identify the species which results from the following movement of electron pairs.
A) A B) B C) C D) D
Ans: A
Page 12
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
53. The most stable resonance contributor of this would be:
A) A B) B C) C D) D
Ans: B
54. What is the molecular formula of aspirin?
O
O
OH
O
A) A B) B C) C D) D
Ans: C
55. Which of the following is not identical to the others?
A
B
C
D
A) A B) B C) C D) D
Ans: D
Page 13
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
56. Which of the line-bond structures below cannot represent a stable molecule?
B.
A.
C.
D.
A) A B) B C) C D) D
Ans: C
57. Which of the electron-movement arrows below are NOT valid?
A.
C
C
C
C
B.
C
C
C
C
C
O
D.
C.
C
A) A B) B C) C D) D
Ans: C
58. What atom would have a formal charge in this structure?
B
A
O
N
C
CH2
O
H
D
A) A B) B C) C D) D
Ans: D
Page 14
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 1 Structure Determines Properties: Answers
Prof. Sivaguru Jayaraman
59. Rank the following in order of decreasing acidity. (more acidic > less acidic)
O
N
H
H
I
II
N
CH3
HO
CH3
H
III
IV
A) I > IV > III > II
B) III > II > I > IV
Ans: A
C)
D)
IV > I > II > III
I > III > IV > II
60. Using resonance principles, on what atom does acid protonate guanidine?
B
H
D
N
A
H2N
C
NH2
C
A) A B) B C) C D) D
Ans: B
61. What structure would result from these electron movement arrows?
?
O
+
O
O
A
B
OH
O
C
D
A) A B) B C) C D) D
Ans: C
62. What would be the line-bond structure for (CH3)3CCH2CH(CH3)2?
A
B
C
D
A) A B) B C) C D) D
Ans: A
Page 15
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
Chapter 2: Hydrocarbon Frameworks - Alkanes
1. Alkanes are characterized by the general molecular formula:
A) CnH2n-2 B) CnH2n C) CnH2n+2 D) CnH2n+4
Ans: C
2. Cycloalkanes are characterized by the general molecular formula:
A) CnH2n-2 B) CnH2n C) CnH2n+2 D) CnH2n+4
Ans: B
3. The carbon-carbon sigma bond in ethane is formed by overlap of which two orbitals?
A) 2p-2p B) sp-sp C) sp2-sp2 D) sp3-sp3
Ans: D
4. What is the IUPAC name of the following compound?
A) 4,4-dimethylpentane
B) 1-tert-butylpropane
Ans: C
C)
D)
2,2-dimethylpentane
1,1,1-trimethylbutane
5. The correct IUPAC name of the following compound is
A) 2-ethyl-3,5-dimethylheptane.
B) 6-ethyl-5,5-dimethylheptane.
Ans: C
C)
D)
3,4,4-trimethyloctane.
5,5,6-trimethyloctane.
6. The common name of the following group is
A) n-butyl.
Ans: B
B) sec-butyl.
C) isobutyl.
D) tert-butyl.
Page 1
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
7. Which one of the following is 2,2,5-trimethylhexane?
A) (CH3)2CHCH2C(CH3)3
C) CH3CH2CH(CH3)C(CH3)3
B) (CH3)2CHCH2CH2C(CH3)3
D) (CH3)2CHCH2 CH2CH2C(CH3)3
Ans: B
8. The correct IUPAC name of the following is
A) 2,4,7-trimethylnonane.
B) 3,6,8-trimethylnonane.
Ans: A
C)
D)
7-ethyl-2,4-dimethyloctane.
2-ethyl-5,7-dimethyloctane.
C)
D)
5-ethyl-6-methylheptane
4-ethyl-3-methylheptane
C)
D)
3-ethyl-1,1-dimethylcyclopentane
4-ethyl-1,1-dimethylcyclopentane
C)
D)
methyl groups.
both methine and methylene groups.
9. What is the IUPAC name of the following?
A) 5,6-diethylhexane
B) 2,3-diethylhexane
Ans: D
10. What is the IUPAC name of the following?
A) 1-ethyl-4.4-dimethylcyclopentane
B) 1-ethyl-3,3-dimethylcyclopentane
Ans: C
11. Cyclohexane is composed of
A) methine groups.
B) methylene groups.
Ans: B
Page 2
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
12. All the carbons in cyclopentane are
A) primary carbons.
B) secondary carbons.
Ans: B
Prof. Sivaguru Jayaraman
C)
D)
tertiary carbons.
quaternary carbons.
13. The correct name of the following compound is
A) (1-methylpropyl)cyclohexane.
B) (2-methylpropyl)cyclohexane.
Ans: B
C)
D)
(2,2-dimethylethyl)cyclohexane.
(2,2-dimethylpropyl)cyclohexane.
14. The correct IUPAC name of the following compound is
A) (1-methylhexyl)cyclopentane.
B) (1-pentylethyl)cyclopentane.
Ans: C
C)
D)
2-cyclopentylheptane.
1-cyclopentyl-2-heptane.
15. The C—C sigma bond in acetylene is formed by the overlap of which two orbitals?
A) 2p-2p
Ans: B
B) sp-sp
C) sp2-sp2
D) sp3-sp3
16. The boiling point of isobutane (-10.2°C) is lower than n-butane (-0.4°C) because
isobutane has
A) weaker intermolecular van der Waals forces.
B) stronger intermolecular van der Waals forces.
C) weaker dipole-dipole attractive forces.
D) stronger dipole-dipole attractive forces.
Ans: A
Page 3
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
17. Which of the following are constitutional isomers?
A) I, II, and III
B) I, III, and IV
Ans: A
C)
D)
only I and III
all are constitutional isomers
18. Arrange the following isomeric alkanes in order of increasing boiling point.
I. n-heptane
II. 2,3-dimethylpentane
III. 2,2,3-trimethylbutane
A) I < II < III B) II < III < I C) III < I < II D) III < II < I
Ans: D
19. The oxidation states of carbon range from
A) 0 to +2. B) 0 to +4. C) –4 to 0. D) –4 to +4.
Ans: D
20. Which of the following has(have) a higher oxidation state of carbon than the carbon in
formaldehyde, H2C=O?
I. CH3OH
II. HCO2H
III. H2CO3
A) I B) III C) II and III D) I, II, and III
Ans: C
21. The tert-butyl group can also be called
A) 1,1-dimethylpropyl.
B) 1,1-dimethylethyl.
Ans: B
C)
D)
2,2-dimethylpropyl.
2,2-dimethylethyl.
Page 4
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
22. Carbon atoms 1, 2, and 3 in the following structure are classified, respectively, as
A) tertiary, primary, secondary.
B) quaternary, primary, tertiary.
Ans: D
C)
D)
quaternary, secondary, secondary.
quaternary, secondary, tertiary.
23. Identify the isomer of C6H14 that only has primary and tertiary carbons.
A) hexane B) 2,2-dimethylbutane C) 3-methylpentane D) 2,3-dimethylbutane
Ans: D
24. Why can heats of combustion of constitutional isomers of hydrocarbons be used to
measure their stabilities?
I. Combustion of constitutional isomers gives different final states.
II. Combustion of constitutional isomers gives the same final states.
III. Constitutional isomers of hydrocarbons have the same potential energies.
IV. Constitutional isomers of hydrocarbons have different potential energies.
A) only I B) only II C) I and III D) II and IV
Ans: D
25. The heats of combustion (-ΔH°) of heptane and 3,3-dimethypentane are 4,817 and 4,809
kJ/mol, respectively. Which statement is true?
A) Heptane is 8 kJ/mol more stable then 3,3-dimethylpentane.
B) 3,3-Dimethylpentane is 8 kJ/mol more stable than heptane.
C) Stabilities cannot be compared since they are not isomers.
D) Stabilities cannot be compared since they give different combustion products.
Ans: B
26. The reaction of acetylene with hydrogen gas is shown below. Which statements are true
concerning the reaction?
I. Acetylene is oxidized to ethane.
II. Acetylene is reduced to ethane.
III. Carbon changes oxidation state from -1 to -3.
IV. Hydrogen (from H2) changes oxidation state from 0 to +1.
A) I and III B) II and IV C) I, III, and IV D) II, III, and IV
Ans: D
Page 5
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
27. How many methine groups are there in isopropylcyclopentane?
A) one B) two C) three D) four
Ans: B
28. What is the total number of constitutional isomers with the formula C5H12?
A) two B) three C) four D) five
Ans: B
29. What is the IUPAC name of the following?
A) 6-isopropyl-3-methylnonane
B) 6-propyl-3-methylnonane
Ans: A
C)
D)
2-ethyl-5-isopropyloctane
2-ethyl-5-propyloctane
30. How many moles of O2 gas would be consumed in the complete combustion of 0.100
mole of C5H12?
A) 0.100 mole O2 B) 0.400 mole O2 C) 0.800 mole O2 D) 1.60 mole O2
Ans: C
31. The systematic name of the following group is
A) 5-ethyl-2-methylpentyl.
B) 1-ethyl-4-methylpentyl.
Ans: B
C)
D)
6-methyl-3-heptyl.
2-methyl-5-heptyl.
32. What is the relationship between the two structures below?
A)
B)
C)
D)
Ans:
identical structures
resonance forms
constitutional isomers
different compounds with different compositions
C
Page 6
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
33. What is the IUPAC name of the following structure?
A) 3-propylpentane B) 3-ethylhexane C) 2-ethylheptane
Ans: B
D) 4-ethylpentane
34. Which of the following are constitutional isomers?
I. 2,3,3-dimethylhexane
II. 2,2-diethylpentane
III. 3-ethyl-2-methylheptane
A) I and II B) I and III C) II and III D) they are all constitutional isomers
Ans: A
35. What is the estimated C—C—C bond angle in the following structure?
A) 90o B) 109.5o
Ans: C
C) 120o
D) 180o
Page 7
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
36. What are the hybridizations of carbon atoms 2, 3, and 4 shown below?
A) sp, sp2, sp2
Ans: D
B) sp, sp2, sp3
C) sp, sp, sp2 D) sp, sp, sp3
37. Arrange the following hydrocarbons in order of increasing boiling point.
I. pentane
II. 2,2-dimethylpropane
III. 2-methylbutane
A) I < II < III B) I < III < II C) II < I < III D) II < III < I
Ans: D
38. The 1,1-dimethylethyl group, -C(CH3)3, can also be called
A) butyl. B) isobutyl. C) sec-butyl. D) tert-butyl.
Ans: D
39. What is the relationship between the following two structures?
A)
B)
C)
D)
Ans:
identical structures
resonance forms
constitutional isomers
different compounds with different compositions
A
40. The sp3 orbitals of carbon in CH4 are formed from the
A) three 2p orbitals.
C) 2s and two of the 2p orbitals.
B) 2s and one of the 2p orbitals.
D) 2s and the three 2p orbitals.
Ans: D
Page 8
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
41. The geometry of sp3 hybrid orbitals can be described as pointing towards the corners of
a
A) triangle. B) square. C) tetrahedron. D) square pyramid.
Ans: C
42. What is the Cl—C—Cl bond angle in CCl4?
A) 60o B) 90o C) 109.5o D) 120o
Ans: C
43. Which of the following has the lowest boiling point?
A) pentane B) 2,2-dimethylpropane C) 2-methylbutane
Ans: B
D) hexane
44. Low octane fuels
A) generate less energy when burned.
B) burn slower than high-octane fuels.
C) burn faster than high-octane fuels.
D) contain less octane (C8H18) than high-octane fuels.
Ans: C
45. The shortest and longest carbon-carbon bonds, respectively, in this molecule are:
A) II and III
Ans: D
B) IV and III
C) I and IV
D) IV and I
46. How many isomers of C6H14 are possible?
A) four B) five C) six D) seven
Ans: B
Page 9
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 2 Hydrocarbon Frameworks – Alkanes: Answers
Prof. Sivaguru Jayaraman
47. Which of the molecules below is NOT an isomer of formula C6H14?
A
B
A) A B) B C) C D) D
Ans: B
C
D
48. What is the molecular formula of menthene?
A) C10H16
Ans: B
B) C10H18
C) C10H19
D) C10H20
49. How many isomers of C4H9Cl are possible?
A) two B) three C) four D) five
Ans: C
50. The smallest straight-chain alkane that is liquid at room temperature and atmospheric
pressure is
A) propane B) butane C) pentane D) hexane
Ans: C
51. The lowest-boiling isomer of C7H16 would be
A
B
C
A) A B) B C) C D) D
Ans: C
D
52. Which of the following is true in combustion reactions?
A) all carbon always becomes CO2
C) high octane fuels release more
energy
B) all hydrogen always becomes water D) all carbon always becomes CO
Ans: B
Page 10
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
Chapter 3: Conformations of Alkanes and Cycloalkanes
1. Identify the conformation of butane shown below.
A) anti
Ans: B
B) gauche C) skewed
D) eclipsed
2. What is the IUPAC name of the compound shown in the following Newman projection?
A) 1,1,2,2-tetramethylethane
B) 1,2-dimethylethane
Ans: D
C)
D)
2,2,3,3-tetramethylbutane
2,3-dimethylbutane
3. What is the IUPAC name of the compound shown below?
A) 1,2,3-trimethylbutane
B) 2,3-dimethylpentane
Ans: B
C)
D)
2,3,4-trimethylpentane
2-isopropylbutane
Page 1
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
4. What is the dihedral (torsion) angle between the two bromine atoms in the following
sawhorse drawing?
A) 0o B) 30o
Ans: C
C) 60o
D) 90o
5. At room temperature, the various conformations of butane
A) do not interconvert; only the anti form is present.
B) do not interconvert, but all conformations are present.
C) interconvert very slowly.
D) interconvert very rapidly.
Ans: D
6. Which statement is correct concerning the relative stabilities of the two conformations,
A and B, below?
A)
B)
C)
D)
A is more stable.
B is more stable.
A and B are equal in stabilities.
A and B are not equal in stability, but the preferred conformation cannot be
determined by inspection.
Ans: C
Page 2
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
7. Identify the spatial relationship of the two chlorine atoms.
A) gauche B) anti
Ans: B
C) eclipsed
D) twist
8. Which statement is correct concerning the relative stabilities of the two conformations,
A and B, below?
A)
B)
C)
D)
A is more stable.
B is more stable.
A and B are equal in stabilities.
A and B are not equal in stability, but the preferred conformation cannot be
determined by inspection.
Ans: B
9. What is the IUPAC name of the following compound?
A) trans-1,4-dimethylcyclohexane
B) cis-1,4-dimethylcyclohexane
Ans: A
C)
D)
trans-1,3-dimethylcyclohexane
cis-1,3-dimethylcyclohexane
Page 3
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
10. What is the dihedral (torsion) angle between the two bromine atoms in the wedge-anddash drawing below?
A) 60o B) 90o
Ans: D
C) 120o
D) 180o
11. Identify the relationship between the following two structures.
A)
B)
C)
D)
Ans:
constitutional isomers
stereoisomers
different conformations of the same compound
identical
C
12. Predict which of the following constitutional isomers of C5H10 would have the highest
heat of combustion?
A) methylcyclobutane
C) cis-1,2-dimethylcyclopropane
B) cyclopentane
D) trans-1,2-dimethylcyclopropane
Ans: C
13. Identify the two atoms anti to the bromine.
A) the equatorial H's on C-2 and C-6
B) the axial H's on C-2 and C-6
Ans: D
C)
D)
C-2 and C-6
C-3 and C-5
Page 4
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
14. Cyclohexane adopts the chair conformation rather than a planar structure because
I. torsional strain is minimized.
II. the C—C—C bond angles are close to 109.5o.
III. there are no 1,3-diaxial interactions in a planar structure.
A) only I B) only II C) I and II D) I, II, and III
Ans: C
15. Identify the relationship between the following two structures.
A)
B)
C)
D)
Ans:
constitutional isomers
stereoisomers
different conformations of the same compound
identical
B
16. The most stable conformation of the compound shown has
A)
B)
C)
D)
Ans:
all methyl groups equatorial.
equatorial methyl groups at C-1 and C-2, axial at C-4.
equatorial methyl groups at C-1 and C-4, axial at C-2.
equatorial methyl groups at C-2 and C-4, axial at C-1.
D
17. The most stable chair conformation of cis-1-tert-butyl-3-methylcyclohexane has
A) both groups equatorial.
B) both groups axial.
C) the tert-butyl group equatorial and the methyl group axial.
D) the tert-butyl group axial and the methyl group equatorial.
Ans: A
Page 5
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
18. Identify the relationship of the two compounds below.
A)
B)
C)
D)
Ans:
identical
constitutional isomers
stereoisomers
different conformations of the same compound
C
Page 6
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
19. Identify the correct stereoisomer and the most stable conformation of the following
compound.
A) A B) B C) C D) D
Ans: B
Page 7
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
20. Identify the relationship of the two compounds below.
A)
B)
C)
D)
Ans:
identical
constitutional isomers
stereoisomers
different conformations of the same compound
A
21. What is the IUPAC name of the following compound?
A) bicyclo[2.2.2]octane
B) bicyclo[2.2.2]hexane
Ans: A
C)
D)
bicyclo[3.3.3]octane
bicyclo[3.3.3]hexane
22. Which statement below is true concerning the conversion of cis-1,4dimethylcyclohexane to trans-1,4-dimethylcyclohexane?
A) The conversion takes place by chair conformation ring-flipping.
B) You cannot do the conversion without breaking covalent bonds.
C) The conversion takes place by rotating the C(1)-C(2) bond by 180°.
D) The conversion takes place through the skew boat conformations.
Ans: B
23. What is the IUPAC name of the following bicycloalkane?
A) bicyclo[6.3.0]heptane
B) bicyclo[4.1.0]hexane
Ans: D
C)
D)
bicyclo[4.2.1]hexane
bicyclo[4.1.0]heptane
Page 8
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
24. Identify the relationship between the following two structures.
A)
B)
C)
D)
Ans:
identical
different conformations of the same compound
stereoisomers
constitutional isomers
C
Page 9
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
25. Which isomer of 1-tert-butyl-3-ethyl-5-methylcyclohexane below is thermodynamically
the most stable?
A) A B) B C) C D) D
Ans: A
26. What would the C—C—C bond angles be in a planar cyclohexane?
A) 60o B) 90o C) 109.5o D) 120o
Ans: D
Page 10
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
27. Identify the relationship between the following two Newman projections.
A)
B)
C)
D)
Ans:
identical
stereoisomers
different conformations of the same compound
constitutional isomers
C
28. The IUPAC name of the following compound is
A) cis-1,2-dimethylcyclohexane.
B) trans-1,2-dimethylcyclohexane.
Ans: A
C)
D)
1,1-dimethylcyclohexane.
cis-1,3-dimethylcyclohexane.
C)
D)
trans-1,3-dimethylcyclohexane.
trans-1,4-dimethylcyclohexane.
29. The following structure is
A) cis-1,3-dimethylcyclohexane.
B) cis-1,4-dimethylcyclohexane.
Ans: C
Page 11
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
30. The sawhorse drawing of butane below is
A)
B)
C)
D)
Ans:
a gauche conformation.
the anti conformation.
the least stable eclipsed conformation.
the most stable eclipsed conformation.
A
31. The sawhorse drawing of butane below is the
A) least stable staggered conformation.
B) most stable staggered conformation.
Ans: C
C)
D)
least stable eclipsed conformation.
most stable eclipsed conformation.
32. Which constitutional isomer of dimethylcyclohexane does not exhibit cis-trans
isomerism?
A) 1,1-dimethylcyclohexane
C) 1,3-dimethylcyclohexane
B) 1,2-dimethylcyclohexane
D) 1,4-dimethylcyclohexane
Ans: A
Page 12
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
33. What is the estimated dihedral angle between the two methyl groups on the structure
shown below?
A) 30o B) 60o
Ans: B
C) 90o
D) 120o
34. Which one of the following is a stereoisomer isomer of trans-1,3dimethylcyclopentane?
A) 1,1-dimethylcyclopentane
C) ethylcyclopentane
B) cis-1,2-dimethylcyclopentane
D) cis-1,3-dimethylcyclopentane
Ans: D
35. Which of the following best describes the conformation of propane shown below?
A)
B)
C)
D)
Ans:
C(1) - C(2) staggered and C(2) - C(3) staggered
C(1) - C(2) staggered and C(2) - C(3) eclipsed
C(1) - C(2) eclipsed and C(2) - C(3) staggered
C(1) - C(2) eclipsed and C(2) - C(3) eclipsed
C
Page 13
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
36. Which one of the following is the butane conformation shown below?
A) gauche B) anti
Ans: A
C) skew
D) eclipsed
37. What is the correct IUPAC name of the following compound?
A) cis-1-ethyl-2-methylcyclohexane
B) trans-1-ethyl-2-methylcyclohexane
Ans: B
C)
D)
cis-1-ethyl-6-methylcyclohexane
trans-1-ethyl-6-methylcyclohexane
38. Which of the following can have cis-trans stereoisomers?
A) 1,1-dimethylcyclobutane
C) 1,1,3-trimethylcyclobutane
B) 1,3-dimethylcyclobutane
D) 1,1,3,3-tetramethylcylclobutane
Ans: B
39. The C—C—C bond angle in cyclopropane is
A) 60o. B) 90o. C) 109.5o. D) 120o.
Ans: A
40. The most stable conformation of cis-4-methyl-1-tert-butylcyclohexane is a chair
conformation with
A) both the -CH3 and -C(CH3)3 equatorial.
B) both the -CH3 and -C(CH3)3 axial.
C) the -CH3 equatorial and the -C(CH3)3 axial.
D) the -CH3 axial and -C(CH3)3 equatorial.
Ans: D
Page 14
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
41. What is the IUPAC name of the compound shown below?
A) cis-1,3-dimethylcyclohexane
B) trans-1,3-dimethylcyclohexane
Ans: B
C)
D)
cis-1,4-dimethylcyclohexane
trans-1,5-dimethylcyclohexane
42. What is the IUPAC name of the compound shown below?
A) cis-1,2-diethylcyclobutane
B) trans-1,2-diethylcyclobutane
Ans: C
C)
D)
cis-1,3-diethylcyclobutane
trans-1,3-diethylcyclobutane
43. Which is more stable, cis-1,3-dimethylcyclohexane or trans-1,3-dimethylcyclohexane?
A) trans-1,3-dimethylcyclohexane
B) cis-1,3-dimethylcyclohexane
C) They are equally stable.
D) Stabilities of cis, trans stereoisomers cannot be compared.
Ans: B
Page 15
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
44. What is the relationship between the following two structures?
A)
B)
C)
D)
Ans:
identical
stereoisomers
different conformations of the same compound
constitutional isomers
D
45. How many alkyl groups would be equatorial in the most stable conformation of the
cyclohexane below?
A) one B) two
Ans: B
C) three
D) four
46. Menthol is the most stable isomer of 2-isopropyl-5-methylcyclohexanol. Which
compound is it?
A) A B) B C) C D) D
Ans: C
Page 16
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
47. The planar form of which ring would have bond angles close to the tetrahedral value
but is destabilized by eclipsing interactions?
A
B
C
A) A B) B C) C D) D
Ans: C
D
48. Consider these two molecules; which statement is true?
I
II
A) I is more stable than II.
B) II is more stable than I.
Ans: B
C)
D)
I and II are equally stable.
There is no way to predict this.
49. Which of the staggered conformations of 2-methylbutane is most stable?
CH3
CH3
H
H
CH3
A
H3 C
H CH3
H3CCH3
CH3
H
CH3
H
H
B
H
H
H
H
CH3
H CH
CH3
H
3
D
C
A) A B) B C) C D) D
Ans: A
50. What would be the least stable isomer of 1,2,3,4,5,6-hexamethylcyclohexane?
A
B
C
D
A) A B) B C) C D) D
Ans: A
Page 17
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 3 Conformations of Alkanes and Cycloalkanes: Answers
Prof. Sivaguru Jayaraman
51. What is the most specific name for the conformation shown?
H
CH3
CH3
H
H
H
A) anti
Ans: C
B) staggered
C) gauche
D) eclipsed
52. β-D-Glucose is the six-carbon sugar with all non-hydrogen groups equatorial. Which
structure is it?
CH2OH
CH2OH
HO
HO
O
HO
A
OH
HO
HO
O
OH
HO
OH
O
O
OH
B
CH2OH
CH2OH
HO
OH
C
OH
HO
OH
D
A) A B) B C) C D) D
Ans: B
Page 18
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
OH
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
Chapter 7: Stereochemistry
1. Which of the molecules below are chiral?
A) only II
Ans: D
B) only III
C) I and III
D) II and III
2. Which of the molecules below are chiral?
A) only I
Ans: B
B) I and III
C) II and III
D) I, II, and III
3. Identify the chiral compound(s) below.
A) only II
Ans: A
B) II and III
C) III and IV D) I, II, and IV
Page1
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
4. Which of the following molecules are chiral?
A) only II
Ans: A
B) only III
C) II and III
D) I, II, and III
5. How many stereogenic centers are there in the following molecule?
A) only 1
Ans: B
B) two
C) three D) four
6. How many stereogenic centers are there in the following molecule?
A) only 1
Ans: C
B) two
C) three D) four
7. Give the configurations, respectively, of the following two molecules.
A) R and R
Ans: B
B) R and S
C) S and S
D) S and R
Page2
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
8. Give the configurations, respectively, of the following two molecules.
A) R and R
Ans: A
B) R and S
C) S and S
D) S and R
9. Which one of the following groups has the highest rank as assigned by the Cahn-IngoldPrelog system for stereogenic carbons?
A) –CH=CH2 B) –CH2OH C) –CH=O D) –CH2SH
Ans: D
10. Give the configurations of carbons 1 and 2, respectively, in the structure shown below.
A) R and R
Ans: B
B) R and S
C) S and S
D) S and R
11. What is the IUPAC name of the following compound?
A) (2S, 3S)-2,3-dibromopentane
B) (2S, 3R)-2,3-dibromopentane
Ans: D
C)
D)
(2R, 3S)-2,3-dibromopentane
(2R, 3R)-2,3-dibromopentane
12. Which of the following statements are true?
I. If a molecule has a plane of symmetry it is achiral.
II. If a molecule has a center of symmetry it is achiral.
III. If a molecule has one stereogenic center it is chiral.
A) I and II B) I and III C) II and III D) I, II, and III
Ans: D
Page3
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
13. What is the relationship between the following two molecules?
A) identical
Ans: A
B) enantiomers C) diastereomers
D) constitutional isomers
14. What are the configurations of carbons 2 and 3 in the Fischer projection below?
A) 2R, 3R B) 2R, 3S
Ans: D
C) 2S, 3R
D) 2S, 3S
15. Compound X, C5H10O, is optically active. The compound consumes one equivalent of
hydrogen to give C5H12O. The hydrogenation product is also optically active. Which
compound below matches the information?
A) A B) B C) C D) D
Ans: D
16. A pure sample of (S)-phenylalanine has a specific rotation of +70°. A mixture of the two
enantiomers of phenylalanine has a specific rotation of +7.0°. What are the percentages
of the S and R enantiomers in the mixture?
A) 95% S, 5% R
C) 55% S, 45% R
B) 90% S, 10% R
D) 52.5% S, 47.5% R
Ans: C
Page4
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
17. How many stereoisomers are there for the compound shown below?
A) two B) four
Ans: A
C) six
D) eight
18. Give the total number of stereoisomers of 2,3-dibromobutane.
A) none, only a single structure B) two C) three D) four
Ans: C
19. What is the relationship between the following two compounds?
A) identical
Ans: D
B) enantiomers C) diastereomers
D) constitutional isomers
20. What is the relationship between the following two compounds?
A)
B)
C)
D)
Ans:
different conformations of the same compound
enantiomers
diastereomers
constitutional isomers
C
21. (+)–Tartaric acid has a specific rotation of +12.0°. What is the specific rotation of a
mixture of 75% (+)–tartaric acid and 25% (–)–tartaric acid?
A) +4.0° B) +6.0° C) +8.0° D) +9.0°
Ans: B
22. The addition of bromine, Br2, to trans-2-butene gives
A) (2R,3R)-2,3-dibromobutane.
B) (2S,3S)-2,3-dibromobutane.
C) a racemic mixture of (2R,3R) and (2S,3S)-2,3-dibromobutane.
D) meso-2,3-dibromobutane.
Ans: D
Page5
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
23. What is the relationship between the following two compounds?
A) identical
Ans: B
B) enantiomers C) diastereomers
D) constitutional isomers
24. In terms of stereochemistry, the following reaction gives
A) a single enantiomer.
B) a racemic pair of enantiomers.
Ans: D
C)
D)
a nonracemic pair of enantiomers.
two diastereomers.
25. Which of the following has a meso stereoisomer?
I. 2,4-dichloropentane
II. 1,3-dimethylcyclopentane
III. 2,3-dichloropentane
A) only I B) only II C) I and III D) I and II
Ans: D
Page6
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
26. Which of the following amines gives a pair of diastereomeric salts when reacted with
(S)-(-)-malic acid?
A) only I
Ans: D
B) only II
C) only III
D) I and III
27. Which of the following C6H10 cycloalkenes would give a pair of diastereomeric
epoxides when reacted with peroxyacetic acid, CH3CO3H?
A) 1-methylcyclopentene
C) 1,2-dimethylcyclobutene
B) 3-methylcyclopentene
D) 3,3-dimethylcyclobutene
Ans: B
28. The addition of HBr to 1-octene gives
A) a racemic mixture of 2-bromooctane.
B) a nonracemic mixture of 2-bromooctane.
C) 1-bromooctane.
D) a racemic mixture of 1,2-dibromooctane.
Ans: A
29. Compound X, C6H10, is optically active. Hydrogenation of the compound gives
methylcyclopentane. Which compound below is compound X?
A) A B) B C) C D) D
Ans: C
Page7
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
30. Which of the following is the best method to make a racemic mixture of (+) and (–)–
2,3-dibromobutane?
A) photochemical bromination of 2-bromobutane
B) addition of HBr to racemic 3-bromo-2-butene
C) addition of Br2 to cis-2-butene
D) addition of Br2 to trans-2-butene
Ans: C
31. Which of the following compounds gives a pair of diastereomers upon epoxidation with
peroxyacetic acid, CH3CO3H?
A) A B) B C) C D) D
Ans: D
32. How many stereoisomers are there of D-fructose (including D-fructose), shown below?
A) four
Ans: C
B) six
C) eight
D) twelve
Page8
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
33. Which of the following Fischer projections corresponds to the compound shown below?
A) A B) B C) C D) D
Ans: A
34. The four isomeric dimethylcyclopropanes are shown below. Identify two of the isomers
which are related as diastereomers.
A) I and III
Ans: C
B) I and IV
C) II and III
D) III and IV
35. How many stereoisomers are there of 1-isopropyl-4-methylcyclohexane?
A) only 1 structure possible - no stereoisomers B) two C) three D) four
Ans: B
36. Which object below is achiral?
A) golf club (wood driver) B) baseball glove C) tennis shoe
Ans: D
37. Which compound below has a meso form?
A) 1,2-dichlorobutane
C)
B) 1,3-dichlorobutane
D)
Ans: C
D) baseball bat
2,3-dichlorobutane
1,4-dichlorobutane
Page9
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
38. Which compound below has no stereoisomers?
A) 1,2-dichlorobutane
C)
B) 1,3-dichlorobutane
D)
Ans: D
Prof. Sivaguru Jayaraman
2,3-dichlorobutane
1,4-dichlorobutane
39. Compound X (C7H12) is optically active. Hydrogenation of compound X gives two
isomeric 1,2-dimethylcyclopentanes, one is optically active and the other is optically
inactive. Of the following compounds, which is the only one that fits the data?
A) A B) B C) C D) D
Ans: C
40. Which sawhorse drawing below has the identical conformation as the following Fischer
projection?
A) A B) B C) C D) D
Ans: B
Page10
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
41. Which one of the following is a diastereomer of (R)-4-bromo-cis-2-hexene?
A) (S)-4-bromo-cis-2-hexene
C) (R)-4-bromo-trans-2-hexene
B) (R)-5-bromo-cis-2-hexene
D) (S)-5-bromo-trans-2-hexene
Ans: C
42. Which of the following statements is false?
A) Racemic mixtures are optically inactive.
B) Enantiomers have specific rotations which are equal, but have opposite signs.
C) Achiral molecules are optically inactive.
D) Meso compounds contain equal amounts of enantiomers.
Ans: D
43. Which reaction below gives a single enantiomer of a chiral product?
A) A B) B C) C D) D
Ans: B
Page11
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
44. Which reaction below gives a pair of diastereomers?
A) A B) B C) C D) D
Ans: A
45. Which one of the following isomeric dibromobutanes is shown below?
A) (2R, 3R)-2,3-dibromobutane
B) (2S, 3S)-2,3-dibromobutane
Ans: C
C)
D)
meso-2,3-dibromobutane
(R)-1,2-dibromobutane
Page12
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
46. The following isomer of dibromohexane can be synthesized by
A) addition of Br2 to trans-3-hexene.
B) addition of Br2 to cis-3-hexene.
Ans: A
C)
D)
addition of HBr to trans-3-hexene.
addition of HBr to cis-3-hexene.
47. What are the configurations of C(1) and C(2), respectively, for the stereoisomer of 2methylcyclopentanol shown below?
A) (1R, 2R)
Ans: B
B) (1R, 2S)
C) (1S, 2R)
D) (1S, 2S)
48. Which one of the following is a diastereomer of (2R,3R)-2,3-dibromopentane?
A) (2S,3S)-2,3-dibromopentane
C) R-1,2-dibromopentane
B) (2S,3R)-2,3-dibromopentane
D) (2R,4R)-2,4-dibromopentane
Ans: B
49. Which of the following is the enantiomer of (2R,3R)-2,3-dibromopentane?
A) (2S,3S)-2,3-dibromopentane
C) (2R,3S)-2,3-dibromopentane
B) (2S,3R)-2,3-dibromopentane
D) (2R,4R)-2,4-dibromopentane
Ans: A
Page13
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
50. What is the IUPAC name of the following hydrocarbon?
A) (R)-4-ethylpentanane
B) (S)-3-methylhexane
Ans: B
C)
D)
(S)-2-ethylpentane
(R)-3-methylhexane
51. What is the total number of stereoisomers (including the one shown) for the following
alcohol?
A) zero (none are possible)
Ans: B
B) two
C) three D) four
52. Which of the following best describes a racemic mixture?
A) A mixture containing equal amounts of two diastereomers.
B) A mixture containing a meso stereoisomer.
C) A mixture containing unequal amounts of enantiomers.
D) A mixture containing equal amounts of enantiomers.
Ans: D
53. Which one of the isomeric C4H9Cl molecules is chiral?
A) 1-chlorobutane
C) 1-chloro-2-methylpropane
B) 2-chlorobutane
D) 2-chloro-2-methylpropane
Ans: B
Page14
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
54. Which of the following molecules is(are) chiral?
A) only I
Ans: A
B) I and II
C) II and III
D) I, II, and III
55. How many stereoisomers of 2,3-pentanediol are possible?
OH
OH
A) 2 B) 3
Ans: C
C) 4
D) 6
56. How many stereoisomers are possible for this structure?
OH
A) 1 B) 4
Ans: C
C) 8
D) 16
57. How many stereoisomers of 2,4-pentanediol are possible?
HO
OH
A) 2 B) 3
Ans: C
C) 4
D) 6
Page15
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
58. The tartaric acid found in fruits, when isolated, exhibits [α] = +12°. Which
configuration is NOT possible for this naturally-occurring material?
OH
HO
tartaric acid
HO2C
CO2H
A) R,R B) R,S
Ans: B
C) S,S
D) there is no way to tell
59. Which statement would be true of this reaction?
Br2
CH3CH2CH2CH3
CH3CH2CHBrCH3
light
A)
B)
C)
D)
Ans:
The organic product is achiral.
The product is racemic.
The product is more of one enantiomer than the other.
There is no way to guess the stereochemistry.
B
60. The most specific description of the relationship between the following two molecules
is:
H
CH3
H
H3C
C
Br
C
and
CH3CH2
A) identical
Ans: A
CH2CH3
Br
B) isomers C) enantiomers
D) diastereomers
61. What are the R/S assignments in this molecule? (assume the carbons are numbered as
shown)
OH
3
HO2C 2
CO2H
OH
A) 2S, 3R B) 2S, 3S
Ans: B
C) 2R, 3S
D) 2R, 3R
Page16
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
62. What is the most important reason that chiral drugs are typically sold as single
enantiomers?
A) one enantiomer is typically a more effective drug
B) one enantiomer is typically cheaper to make
C) racemic mixtures have already been patented
D) one enantiomer is typically easier to separate
Ans: A
63. The free-radical bromination of (R)-2-chlorobutane could produce how many monobromo 2-chlorobutanes? (count all isomers that could be formed, including
stereoisomers)
Br2
only (R)
A) four
Ans: C
H
?
light
Cl
B) five C) six
D) eight
64. (-)-Fenchone can be purchased in 70% optical purity. What ratio of enantiomers is
present?
O
A) 70% (-) : 30% (+)
B) 85% (-) : 15% (+)
Ans: B
C)
D)
55% (-) : 45% (+)
60% (-) : 40% (+)
65. One stereoisomer of the structure below is a poison found in a certain mushroom. How
many stereoisomers of this structure are possible?
HO
N(CH3)3
H3C
O
A) 4 B) 8
Ans: B
C) 16
D) 32
Page17
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 7 Stereochemistry: Answers
Prof. Sivaguru Jayaraman
66. How many chiral centers are present in histrionicotoxin?
A) 2 B) 3
Ans: C
C) 4
D) 5
67. How many chiral centers are in this molecule?
HO
morphine
O
H
HO
A) 2 B) 4
Ans: C
C) 5
N
CH3
D) 6
Page18
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
Chapter 13: Spectroscopy 1. Which of the following isomeric dibromopropanes has only a single peak in its
proton NMR spectrum?
A) 1,1-dibromopropane
C) 1,2-dibromopropane
B) 1,3-dibromopropane
D) 2,2-dibromopropane
Ans: D
2. How many different types(sets) of hydrogens are there in 2,2-dimethylpentane?
A) 2 B) 3 C) 4 D) 5
Ans: C
3. Which of the following has only a single peak in its proton NMR spectrum?
A) only I
Ans: C
B) only II
C) I and II
D) I, II, and III
4. A compound is either cyclononane or cyclodecane. Which of the following is the most
useful technique in identifying the compound?
A) IR spectroscopy B) mass spectrometry C) proton NMR D) C-13 NMR
Ans: B
5. Which of the following gives the furthest downfield shift from TMS in its proton NMR
spectrum?
A) (CH3)4C B) (CH3)3N C) (CH3)2O D) CH3F
Ans: D
6. Which of the following gives the furthest downfield shift from TMS in its proton NMR
spectrum?
A) CCl4 B) CHCl3 C) CH2Cl2 D) CH3Cl
Ans: B
7. How many different sets of equivalent protons are there for para-xylene (1,4dimethylbenzene)?
A) only 1 B) two C) three D) four
Ans: B
1 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
8. How many different sets of equivalent protons are there in the following compound?
A) three
Ans: A
B) four
C) five
D) six
9. What is the multiplicity of the methylene hydrogens indicated in the proton NMR of the
following compound?
A) doublet
Ans: D
B) triplet
C) quartet
D) pentet
10. What is the multiplicity of the methylene hydrogens indicated in the proton NMR of the
following compound?
A) singlet
Ans: A
B) doublet
C) triplet
D) quartet
11. What are the approximate intensities of the four lines in the quartet from the proton
NMR of diethyl ether, (CH3CH2)2O? (Assume distortion of the quartet is minimal.)
A) 1:1:1:1 B) 1:2:2:1 C) 2:3:3:2 D) 1:3:3:1
Ans: D
2 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
12. Which compound below fits the following proton NMR data?
triplet
singlet
quartet
A) A B) B
Ans: B
δ 1.22 (3H)
δ 1.98 (3H)
δ 4.07 (2H)
C) C
D) D
13. The proton NMR of 1,1-dibromoethane would appear as a
A) downfield doublet and upfield quartet.
B) downfield quartet and upfield doublet.
C) downfield doublet and upfield triplet.
D) downfield triplet and upfield doublet.
Ans: B
14. The proton NMR spectrum of a compound gives singlets at δ 2.10 and δ 2.56 in a ratio
of 3:2, respectively. Which compound below is the best match for the spectrum?
A) A B) B
Ans: C
C) C
D) D
3 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
15. The proton NMR of a compound, C8H9ClO, has the following peaks. Which compound
below best fits the data?
broad singlet
triplet
triplet
doublet
doublet
A) I B) II
Ans: C
C) III
δ 2.41 (1H)
δ 2.41 (2H)
δ 3.69 (2H)
δ 7.02 (2H)
δ 7.50 (2H)
D) IV
16. The proton NMR spectrum of a compound, C3H6Cl2, has a pentet at δ 2.19 and a triplet
at δ 3.72 in a 1:2 ratio, respectively. Which compound below best matches the data?
A) A B) B
Ans: B
C) C
D) D
17. A large doublet and a small septet pattern in 1H NMR is usually indicative of a(n)
A) ethyl group. B) propyl group. C) isopropyl group. D) phenyl group.
Ans: C
18. A triplet and quartet pattern in 1H NMR often indicates the presence of a(n)
A) ethyl group. B) propyl group. C) isopropyl group. D) phenyl group.
Ans: A
4 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
19. Which of the following describes the spin-spin splitting of the indicated H in the 1H
NMR of the compound shown below?
A) singlet
Ans: B
B) doublet of doublets
C) triplet
D) doublet of triplets
20. Identify the C4H9Cl isomer given the following proton NMR data:
doublet
multiplet
doublet
A) A B) B
Ans: D
δ 1.04 (6H)
δ 1.95 (1H)
δ 3.35 (2H)
C) C
D) D
21. What region of the electromagnetic spectrum is used in nuclear magnetic resonance
spectroscopy?
A) radio wave B) X-ray C) ultraviolet D) microwave
Ans: A
5 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
22. Which of the compounds below fit the following C-13 NMR?
A) para-dichlorobenzene
B) meta-dichlorobenzene
Ans: C
C)
D)
ortho-dichlorobenzene
chlorobenzene
23. Identify which one of the following isomers of C6H14 has the C-13 NMR below.
A) CH3CH2CH2CH2CH2CH3
B) CH3CH2CH2CH(CH3)2
Ans: D
C)
D)
6 (CH3)2CHCH(CH3)2
CH3CH2C(CH3)3
Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
24. Which one of the following isomers of C8H18 has only two peaks in its 13C NMR?
A) A B) B
Ans: D
C) C
D) D
25. In infrared spectroscopy, absorption of electromagnetic radiation results in transitions
between _________ energy levels.
A) vibrational B) electronic C) rotational D) nuclear
Ans: A
26. In proton NMR , 1H-1H spin-spin splitting is common. Why is there no comparable 13C13
C spin-spin splitting in C-13 NMR?
A) C-13 has a nuclear spin of zero.
B) The probability of two C-13 nuclei being next to each other in a compound is very
low.
C) The coupling constant is very small—too small to be observed.
D) There is 13C-13C spin-spin splitting but because of the complex splitting patterns
decoupling techniques are used to suppress it.
Ans: B
27. What is the multiplicity of the indicated carbon in an off-resonance decoupled C-13
NMR spectrum? (In off-resonance decoupled spectra, direct 13C-1H coupling is
observed.)
A) singlet
Ans: B
B) doublet
C) quartet
D) multiplet
7 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
28. Which one of the following compounds fits the C-13 NMR spectrum shown below?
A) A B) B
Ans: D
C) C
D) D
29. A C-13 NMR spectrum of a compound, C10H14, has five peaks. Two peaks are in the 1030 ppm region and the other three are in the 120-140 ppm area. Which of the following
compounds fits the data?
A) I B) II
Ans: D
C) III
D) IV
30. Which one of the following isomeric C8H18 compounds has five peaks in its 13C NMR
spectrum?
A) octane B) 2-methylheptane C) 3-methylheptane D) 4-methylheptane
Ans: D
8 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
31. Which one of the following has a λmax in its UV-visible spectrum with the longest
wavelength?
A) A B) B
Ans: A
C) C
D) D
9 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
32. The reaction shown below gave two products in a ratio of approximately 1:2. The mass
spectrum of the major product has a base peak at m/z 119. The minor product gave a
base peak at m/z 133. Based on the reaction given and the information on the mass
spectra, which of the following is the major product?
A) A B) B
Ans: D
C) C
D) D
33. Which of the methods below would be most useful in distinguishing between the
following two compounds?
A) UV spectroscopy
B) C-13 NMR
Ans: B
C)
D)
10 IR spectroscopy
mass spectrometry
Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
34. Match each steroid below with its λmax in its UV-visible spectrum.
A) A B) B
Ans: C
C) C
D) D
35. Which C-C bond would most likely break and give fragments in the mass spectrum of
butyl benzene?
A) 1 B) 2
Ans: B
C) 3
D) 4
11 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
36. Which of the following compounds fits the proton NMR shown below?
A) A B) B
Ans: C
C) C
D) D
12 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
37. Which of the following C5H8 compounds best fits the proton NMR spectrum shown
below?
(The numbers above the peaks are integration values.)
A) A B) B
Ans: A
C) C
D) D
13 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
38. Which of the following C4H7OCl compounds best fits the proton NMR spectrum shown
below?
(The numbers above the peaks are integration values.)
A) A B) B
Ans: D
C) C
D) D
14 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
39. Which compound would you expect to give the 1H NMR pattern shown?
A) A B)
Ans: C
B
C)
C
D)
D
15 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
40. The IR spectrum below reveals what functional group, if any?
A) A B)
Ans: C
B
C)
C
D)
D
41. Which compound C4H9Cl would give the 1H NMR shown below?
A) 1-chlorobutane
B) 1-chloro-2-methylpropane
Ans: C
C)
D)
16 2-chlorobutane
2-chloro-2-methylpropane
Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
42. The IR spectrum shown below is most consistent with which structure?
A) A B)
Ans: C
B
C)
C
D)
D
17 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
43. Which structure is most consistent with the 13C NMR shown?
A) A B)
Ans: C
B
C)
C
D)
D
44. What compound of formula C8H10 would exhibit the following 1H NMR:
d 1.2 (t, 3H), d 2.6 (q, 2H), d 7.1 (br. s, 5H)?
A) A B) B
Ans: B
C) C
D) D
18 Chapter 13 Spectroscopy: Answers
Prof. Sivaguru Jayaraman
45. Which of the compounds below would exhibit the FEWEST peaks in the 13C NMR
spectrum?
A) A B) B
Ans: C
C) C
D) D
46. A compound's UV-vis absorption peak where would likely cause a yellow coloration?
A) A B) B
Ans: B
C) C
D) D
19 Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
Chapter 4: Alcohols and Alkyl Halides
1. What is the IUPAC name of the compound below?
A) 5,5-dimethyl-2-hexanol
B) 2,2-dimethyl-5-hexanol
Ans: A
C)
D)
5,5-dimethyl-2-pentanol
2,2-dimethyl-5-pentanol
2. What is the IUPAC name of the compound below?
A) 3-isobutyl-2-hexanol
B) 2-methyl-5-(1-hydroxyethyl)octane
Ans: D
C)
D)
2-methyl-5-propyl-6-heptanol
6-methyl-3-propyl-2-heptanol
3. What is the IUPAC name of the compound below?
A)
B)
C)
D)
Ans:
8-chloro-4-isopropyl-4,7-dimethylnonane
2-chloro-6-isopropyl-3,6-dimethylnonane
2-chloro-3,6,7-trimethyl-6-propyloctane
6-sec-butyl-2-chloro-3,6-dimethyloctane
B
4. Rank the following three compounds in order of increasing boiling point.
I. CH3CH2CH3 II. CH3CH2OH III. CH3OCH3
A) I < II < III B) I < III < II C) II < III < I D) II < I < III
Ans: B
Page 1
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
5. What is the IUPAC name of the following compound?
A) cis-3-methylcyclohexanol
B) trans-3-methylcyclohexanol
Ans: B
C)
D)
6. Which of the following is isobutyl alcohol?
A) CH3CH2CH2CH2OH
C)
B) CH3CH2CH(OH)CH3
D)
Ans: C
cis-5-methylcyclohexanol
trans-5-methylcyclohexanol
(CH3)2CHCH2OH
(CH3)3COH
7. Identify the tertiary alcohol(s).
A) only I
Ans: C
B) only II
C) only III
D) both I and III
8. Identify the tertiary halide(s).
A) I and II
Ans: C
B) II and III
C) III and IV
D) only IV
9. What is the hybridization of the oxygen atom in alcohols?
A) sp B) sp2 C) sp3
Ans: C
Page 2
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
10. What is the nucleophile in the following substitution reaction?
A) A B) B C) C D) D
Ans: C
11. The C—O—H bond angle in alcohols is closest to
A) 90o. B) 109.5o. C) 120o. D) 180o.
Ans: B
12. Rank the following alcohols in order of increasing reaction rate with HBr.
A) II < III < I
Ans: C
B) III < II < I
C) I < III < II D) I < II < III
13. Chlorination of pentane gives a mixture of isomers having the molecular formula
C5H11Cl. The percentage of 1-chloropentane is 22%. Assuming the secondary
hydrogens in pentane are equally reactive to monochlorination, what is the percentage
of 3-chloropentane in the mixture?
A) 48% B) 26% C) 22% D) 14%
Ans: B
14. Which one of the following gives a single monochlorination product?
A) 2,2-dimethylpropane
C) 2,3-dimethylbutane
B) 2,2-dimethylbutane
D) 2-methylpropane
Ans: A
15. Which of the following hydrocarbons has the slowest reaction rate with Br2 and light?
A) CH4 B) CH3CH2CH3 C) CH3CH2CH2CH3 D) (CH3)3CH
Ans: A
Page 3
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
16. Which method or methods would work to quantitatively prepare a sodium ethoxide
solution?
I. CH3CH2OH + NaOH
II. CH3CH2OH + NaH
III. CH3CH2OH + Na
A) I and II B) I and III C) II and III D) I, II, and III
Ans: C
17. What are the products of the following reaction?
A) 1-bromobutane and water
B) 1-bromobutane and hydrogen
Ans: A
C)
D)
butane and HOBr
CH3CH2CH2CH2OBr + hydrogen
18. Which of the following is not a good method to make bromocyclopentane?
A) cyclopentanol plus HBr
C) cyclopentanol plus PBr3
B) cyclopentanol plus NaBr
D) cyclopentane plus Br2 with light
Ans: B
19. Which of the following is most reactive with HBr?
A) CH3OH B) CH3CH2OH C) (CH3)2CHOH D) (CH3)3COH
Ans: D
20. Arrange the following alcohols in order of their decreasing reactivity with HBr (most
reactive first).
A) I > II > III
Ans: B
B) I > III > II
C) III > I > II D) II > III > I
Page 4
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
21. Arrange the following carbocations in order of their decreasing stabilities (most stable
first).
A) I > II > III
Ans: C
B) III > II > I
C) I > III > II D) II > III > I
22. How many monochlorination products do you expect in the following reaction?
A) two
Ans: C
B) three
C) four
D) five
23. Which of the following is the most stable radical?
A) A B) B C) C D) D
Ans: A
Page 5
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
24. Which of the following are the chain propagating steps in the free radical chlorination of
methane?
A) I and III
Ans: D
B) II and VI
C) III and IV
D) III and V
25. What is the product of the following reaction?
BrCH2CH2CH2CH2OH + SOCl2 →
A) ClCH2CH2CH2CH2OH
B) BrCH2CH2CH2CH2SH
Ans: C
C)
D)
BrCH2CH2CH2CH2Cl
ClCH2CH2CH2CH2SOCl
26. Calculate ΔH° of reaction for the free radical bromination of cyclopentane to give
bromocyclopentane.
A) –121 kJ/mol
Ans: B
B) –63 kJ/mol
C) +121 kJ/mol
D) +63 kJ/mol
27. Which constitutional isomer of C6H14 gives only two monochlorination products?
A) 2-methylpentane
C) 2,2-dimethylbutane
B) 3-methylpentane
D) 2,3-dimethylbutane
Ans: D
Page 6
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
28. Consider the following reaction (X = Cl or Br).
Which statement(s) is(are) correct?
I. Statistically the 1-halopropane should be the major isomer.
II. The 2-halopropane to 1-halopropane ratio is largest when X=Br.
III. The 2-halopropane to 1-halopropane ratio is the largest when X=Cl.
A) only II B) only III C) I and II D) I and III
Ans: C
29. The central carbon of the tert-butyl carbocation, (CH3)3C+, is
A) sp2 hybridized with a +1 formal charge.
B) sp2 hybridized with a 0 formal charge.
C) sp3 hybridized with a +1 formal charge.
D) sp3 hybridized with a 0 formal charge.
Ans: A
30. What are the C—C—C bond angles in the tert-butyl carbocation, (CH3)3C+?
A) 60o B) 90o C) 109.5o D) 120o
Ans: D
31. Studies indicate that the methyl radical is trigonal planar. Based on this, which of the
following best describes the methyl radical?
A) The carbon is sp2 hybridized and the unpaired electron occupies an sp2 orbital.
B) The carbon is sp2 hybridized and the unpaired electron occupies a 2p orbital.
C) The carbon is sp3 hybridized and the unpaired electron occupies an sp3 orbital.
D) The carbon is sp3 hybridized and the unpaired electron occupies a 2p orbital.
Ans: B
Page 7
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
32. Dibromination of isopropylcyclopentane gives a product which can be isolated in good
yields. Which of the following would you predict to be this product?
A) A B) B C) C D) D
Ans: B
33. Which of the following is the key intermediate in the chlorination reaction below?
A) A B) B C) C D) D
Ans: B
Page 8
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
34. The structure below is a generalized abbreviation for which class of compounds?
A) ketones B) aldehydes
Ans: B
C) carboxylic acids D) esters
35. Identify the functional group in the boxed area.
A) ester
Ans: A
B) ketone C) carboxylic acid
D) ether
36. What is the IUPAC name of the following compound?
A) 3-methyl-2-butanol
B) 3-methyl-3-butanol
Ans: C
C)
D)
2-methyl-2-butanol
2,2-dimethyl-1-butanol
Page 9
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
37. What is the name of the following compound?
A) cis-3-methylcyclohexanol
B) trans-3-methylcyclohexanol
Ans: B
C)
D)
cis-2-methylcyclopentanol
trans-3-methylcyclopentanol
38. Which of the following mechanistically depicts the protonation of tert-butyl alcohol by
hydrogen bromide?
A) A B) B C) C D) D
Ans: A
39. How many C3H6Cl2 constitutional isomers do you expect in the dichlorination of
propane?
A) two B) three C) four D) five
Ans: C
Page 10
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
40. What is the IUPAC name of the following alcohol?
A) trans-4-methylcyclohexanol
B) cis-4-methylcyclohexanol
Ans: A
C)
D)
trans-3-methylcyclohexanol
cis-3-methylcyclohexanol
41. Upon free-radical chlorination, the alkane shown would yield
C
C
C
C
C
A) a single monochloride
B) two isomeric dichlorides
Ans: D
C)
D)
three isomeric monochlorides
four isomeric monochlorides
42. What is the major product in the mono-chlorination of pentane?
Cl
Cl
Cl
C C C C C
C C C C C
C C C C C
A
B
C
D. none of these is formed.
A) A B) B C) C D) D
Ans: B
Page 11
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
43. If the compound below containing three types of alcohols were exposed to ONLY 1
equivalent of HCl, what major product would you expect?
OH
1 HCl
HOCH2
?
OH
OH
ClCH2
OH
OH
Cl
HOCH2
A
Cl
HOCH2
B
OH
C
D: there is no way to know.
A) A B) B C) C D) D
Ans: B
44. Which of these five-carbon alcohols would you expect to be most water soluble?
OH
B
A
A) A B) B C) C D) D
Ans: B
C
45. The reaction shown below is what type?
Cl•
+
CH4
A) addition
Ans: C
B) termination
HCl
OH
OH
OH
+ H3C•
C) propagation D) initiation
46. Which halogen forms the weakest bond to carbon?
A) F B) Cl C) Br D) I
Ans: A
Page 12
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
D
Chapter 4 Alcohols and Alkyl Halides: Answers
Prof. Sivaguru Jayaraman
47. If you wanted to get the best yield of compound B from compound A, you would:
X
?
compound A
compound B
A) use chlorine + light rather than bromine + light
B) use bromine + light rather than chlorine + light
C) neither would give >50% yield
D) either would give >50% yield
Ans: A
48. Where would this reaction occur fastest in this molecule?
A
B
Br2
?
light
D
C
A) A B) B C) C D) D
Ans: A
Page 13
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
Chapter 8: Nucleophilic Substitution
1. Identify the nucleophile in the following reaction.
A) CH3Br
Ans: B
B) OH¯
C) H2O
D) Br¯
2. Identify the leaving group in the following reaction.
A) CH3CH2Br
Ans: C
B) HS¯
C) Br¯
D) CH3OH
3. Which of the following cannot act as a nucleophile?
A) NH3 B) H2O C) I¯ D) CH4
Ans: D
4. In the SN2 reaction, the "2" stands for
A) two reactants in the reaction.
B) two steps in the reaction.
Ans: D
C)
D)
two intermediates in the reaction.
bimolecular kinetics for the reaction.
5. Which of the following undergoes a substitution reaction with sodium cyanide in
DMSO at the fastest rate?
A) CH3CH2F B) CH3CH2Cl C) CH3CH2Br D) CH3CH2I
Ans: D
6. 1-Chloro-4-fluorobutane is reacted with one equivalent of sodium iodide in acetone.
During the reaction a precipitate forms. What is the precipitate?
A) FCH2CH2CH2CH2I B) ClCH2CH2CH2CH2I C) NaCl D) NaF
Ans: C
7. The rate law for the following reaction is
A) rate = k[CH3CH2CH2Cl].
B) rate = k[CH3CH2CH2Cl][NaCN].
Ans: B
C)
D)
rate = k[CH3CH2CH2Cl][NaCN]2.
rate = k[NaCN].
Page 1
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
8. Which of the following reacts the fastest by the SN2 mechanism?
A) CH3Br B) CH3CH2Br C) (CH3)2CHBr D) (CH3)3CBr
Ans: A
9. Give the product(s) of the following reaction?
A) A B) B C) C D) a mixture of A and B
Ans: B
10. Which halide ion reacts the fastest with cyclopentyl p-toluenesulfonate in
ethanol/water?
A) A B) B C) C D) D
Ans: A
Page 2
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
11. Which one of the following species forms the strongest ion-dipole attraction with 18crown-6?
A) F- B) K+
Ans: B
C) Cr2O72-
D) Br2
12. Identify the major product(s) in the reaction of (R)-2-bromopentane with sodium
cyanide in DMSO?
A) (R)-2-cyanopentane
C) racemic mixture of 2-cyanopentane
B) (S)-2-cyanopentane
D) trans-2-pentene
Ans: B
13. Which of the following reacts fastest with methanol by the SN1 mechanism?
A) A B) B C) C D) D
Ans: C
14. A pentacoordinate carbon is a transition state in the _____ mechanism.
A) SN1 B) SN2 C) E1 D) E2
Ans: B
Page 3
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
15. What is the leaving group in the following reaction?
A) OHAns: B
B) H2O
C) CH3CH2+
D) C1-
16. Considering the SN1, SN2, E1, and E2 mechanisms, the energy diagram shown below
corresponds to
A) only the SN1 mechanism.
B) only the SN2 mechanism.
Ans: D
C)
D)
both the SN1 and E1 mechanisms.
both the SN2 and E2 mechanisms.
17. Which of the following is the rate law for the SN1 mechanism of an alkyl halide with a
nucleophile?
A) rate = k[alkyl halide]
C) rate = k[alkyl halide][nucleophile]
B) rate = k[nucleophile]
D) rate = k[alkyl halide]2[nucleophile]
Ans: A
18. Which of the following bases works best to maximize the E2 product in the reaction
shown below?
A) KOCH2CH3
Ans: C
B) NaOCH2CH3
C) NaOC(CH3)3
D) NaOH
19. Which of the following does not correctly describe SN2 reactions of alkyl halides?
A) Tertiary halides react faster than secondary halides.
B) Rate of reaction depends on the concentrations of both the alkyl halide and the
nucleophile.
C) The mechanism consists of a single step with no intermediates.
D) The transition state species has a pentavalent carbon atom.
Ans: A
Page 4
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
20. Identify the substitution product(s) in the following reaction.
A) A B) B C) C D) a mixture of A and B
Ans: D
Page 5
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
21. What is the major product of the following reaction?
A) A B) B C) C D) D
Ans: C
22. Starting with 1-hexene, which synthetic sequence below gives 2-cyanohexane?
A) (1) H2SO4 (cat.), H2O
(2) NaCN
B) (1) HBr/peroxide
(2) NaCN
C) (1) HBr
(2) NaCN
D) (1) Br2, H2O
(2) NaCN
Ans: C
Page 6
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
23. Which sequence of reactions below gives the highest yield of ethyl isopropyl ether?
A) A B) B C) C D) D
Ans: B
24. In the solvolysis of t-butyl chloride, a minor product is 2-methylpropene, which results
from the:
A)
B)
C)
D)
Ans:
E2 mechanism with OH¯ acting as the base.
E2 mechanism with H2O acting as the base.
E1 mechanism with OH¯ acting as the base.
E1 mechanism with H2O acting as the base.
D
25. What is the rate limiting step in the following reaction?
A) A B) B C) C D) D
Ans: A
Page 7
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
26. The mechanism of the following reaction is
A) SN1.
Ans: B
B) SN2.
C) E1.
D) E2.
27. Which of the following reacts the slowest with sodium cyanide, NaCN?
A) A B) B C) C D) D
Ans: B
28. How would you synthesize the following compound starting with optically pure (R) or
(S)-2-butanol?
A)
B)
C)
D)
Ans:
(1) (R)-2-butanol + TsCl
(1) (S)-2-butanol + TsCl
(1) (S)-2-butanol + H2SO4 (heat)
(R)-2-butanol + NaCN/DMSO
A
(2) NaCN/DMSO
(2) NaCN/DMSO
(2) HBr
(3) NaCN/DMSO
Page 8
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
29. Starting with optically pure (R) or (S)-2-butanol which method below would give the
best yield of the following ether?
A)
B)
C)
D)
Ans:
(1) (R)-2-butanol + TsCl (2) CH3ONa
(1) (S)-2-butanol + TsCl (2) CH3ONa
(1) (R)-2-butanol + Na
(2) CH3I
(1) (S)-2-butanol + Na
(2) CH3I
D
30. Which of the following conditions favor the SN1 mechanism as opposed to the SN2
mechanism?
I. tertiary alkyl halide
II. primary alkyl halide
III. polar solvent
A) only I B) only II C) I and III D) II and III
Ans: C
31. The species shown below represents the transition state for the
A)
B)
C)
D)
Ans:
reaction of 1-propanol with HBr.
reaction of 1-bromopropane with OH–.
elimination of HBr from 1-bromopropane.
addition of HBr to propene with peroxides.
B
32. The species shown below represents the transition state for the
A)
B)
C)
D)
Ans:
reaction of 1-propanol with HBr.
reaction of 1-bromopropane with OH–.
addition of HOBr to 1-propene.
addition of HBr to propene with peroxides.
A
Page 9
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
33. Which of the following is the double substitution product of the reaction below?
A) A B) B C) C D) D
Ans: A
Page 10
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
34. Starting with 1-methylcyclohexene, which of the following reaction sequences is the
best synthesis of the azide shown below?
A) A B) B C) C D) D
Ans: C
35. Rank the following in decreasing order of leaving group ability.
A) I > III > IV > II
B) I > III > II > IV
Ans: B
C)
D)
III > II > I > IV
II > I > III > IV
36. Identify the mechanistic pathways, respectively, for the products in the following
reaction.
A) E1, SN1
Ans: D
B) E1, SN2
C) E2, SN1
D) E2, SN2
Page 11
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
37. Identify the mechanistic pathways, respectively, for the products in the following
reaction.
A) E1, SN1
Ans: A
B) E1, SN2
C) E2, SN1
D) E2, SN2
38. What is the major product in the following reaction?
A) A B) B C) C D) D
Ans: D
Page 12
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
39. Which of the following mechanistic steps is the most likely route for the formation of
the cyclic ether shown?
A) A B) B C) C D) D
Ans: C
40. In which of the solvents below would the reaction shown take place at the fastest rate?
A) ethanol
Ans: C
B) acetic acid
C) dimethyl sulfoxide
D) water
41. Consider the reaction of each of the following with 1-bromopentane. Which one would
have the highest elimination/substitution ratio?
A) NaOCH2CH3, ethanol, 55oC
C) KOC(CH3)3, (CH3)3COH, 55oC
o
B) NaSH, ethanol-water, 25 C
D) KCN, DMSO, 40oC
Ans: C
Page 13
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
42. Which one of the following correctly describes the reaction below?
A) A B) B C) C D) D
Ans: D
43. Which of the following undergoes SN1 solvolysis in ethanol/water at the fastest rate?
A) A B) B C) C D) D
Ans: A
44. The major product of the following reaction is an alcohol. Which of the following best
describes this reaction?
A) SN2 with inversion of configuration
B) SN2 with racemization
Ans: D
C)
D)
SN1 with inversion of configuration
SN1 with racemization
Page 14
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
45. What reagent would you choose to get the best yield of this product?
A) CH3ONa B) CH3CH2OK
Ans: D
C) (CH3)2CHONa
D) (CH3)3COK
46. The major product(s) of this reaction would be
CH3OH
(R) only
A) only (R)
Ans: C
H
?
Br
B) only (S)
C) (R) and (S)
D) achiral
47. The major product(s) of this reaction would be
(R) only
A) only (R)
Ans: B
CH3SNa
H
?
Br
B) only (S)
C) (R) and (S)
D) achiral
48. The major product(s) of this reaction would be
(R) only
A) only (R)
Ans: D
CH3ONa
H
Br
B) only (S)
C) (R) and (S)
?
D) achiral
49. Which mechanism is least important for reactions of alkyl halides and sulfonates?
A) SN1 B) SN2 C) E1 D) E2
Ans: C
Page 15
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 8 Nucleophilic Substitution: Answers
Prof. Sivaguru Jayaraman
50. The major product expected from the reaction below would be
CH3
Br
NaCN
?
CH3OH
CH3
CH3
CH3
CH2
OCH3
CN
A
B
A) A B) B C) C D) D
Ans: C
C
D
51. What major product, if any, is expected here?
I
CH3
CH3OH
?
cis + trans
OCH3
OCH3
CH3
CH3
CH3
cis + trans
A
B
A) A
Ans: C
C
D: no reaction occurs
B) B C) C D) D
Page 16
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
Chapter 5: Structure and Preparation of Alkenes –
Elimination Reactions
1. Carbon-carbon double bonds do not freely rotate like carbon-carbon single bonds. Why?
A) The double bond is much stronger and thus more difficult to rotate.
B) Overlap of the two 2p orbitals of the π bond would be lost.
C) The shorter bond length of the double bond makes it more difficult for the
attached groups to pass each other.
D) Overlap of the sp2 orbitals of the carbon-carbon σ bond would be lost.
Ans: B
2. What is the IUPAC name of the following compound?
A) 2,5-dimethyl-1-hexene
B) 1,4-dimethyl-1-hexene
Ans: A
C)
D)
2,5-dimethyl-2-hexene
2,5-dimethyl-5-hexene
3. What is the IUPAC name of the following compound?
A) 2-methyl-3-propyl-2-pentene
B) 3-ethyl-2-methyl-2-hexene
Ans: B
C)
D)
4-ethyl-5-methyl-4-hexene
4-methyl-3-propyl-3-pentene
4. What is the IUPAC name of the following compound?
A) 3-ethyl-8-methyl-3-nonene
B) 7-ethyl-2-methyl-6-nonene
Ans: A
C)
D)
1,1-diethyl-6-methyl-3-heptene
3-ethyl-7-isopropyl-3-octene
5. How many isomeric alkenes of formula C4H8, including stereoisomers, are possible?
A) two B) three C) four D) five
Ans: C
Page 1
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
6. How many isomeric alkenes of formula C5H10, including stereoisomers, are possible?
A) three B) four C) five D) six
Ans: D
7. What is the IUPAC name of the following compound?
A) 3-bromo-2-methylcyclohexene
B) 1-bromo-2-methyl-2-cyclohexene
Ans: C
C)
D)
6-bromo-1-methylcyclohexene
2-bromo-1-methylcyclohexene
8. What is the IUPAC name of the following compound?
A) 3-ethyl-propyl-1-heptene
B) ethyl-3-vinyloctane
Ans: D
C)
D)
4,6-diethyl-1-octene
3,5-diethyl-1-octene
9. Which of the following alkenes exhibit E-Z isomerism?
I.
CH3CH2CH CHCH2CH3
II.
(CH3)2C CHCH3
III.
CH3CH2CH CHBr
IV.
H2C CHCH2CH(CH3)2
A) I and II
Ans: B
B) I and III
C) II and IV D) I, II, and III
10. Which of the following alkenes exhibit E-Z isomerism?
I. 1-chloropropene II. 2-chloropropene III. 3-chloropropene
A) only I B) I and II C) II and III D) I and III
Ans: A
Page 2
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
11. What is the IUPAC name of the following compound?
A)
B)
C)
D)
Ans:
(E)-3-bromo-1-fluoro-2-methylpropene
(Z)-3-bromo-1-fluoro-2-methylpropene
(E)-1-bromo-3-fluoro-2-methylpropene
(Z)-1-bromo-3-fluoro-2-methylpropene
A
12. Which of the following C6H12 isomers has the highest heat of combustion?
A) 1-hexene B) trans-3-hexene C) cis-3-hexene D) 2-methyl-2-pentene
Ans: A
13. Identify the major organic product expected from the acid-catalyzed dehydration of 2methyl-2-pentanol.
A) 2-methyl-1-pentene
C) 3-methyl-1-pentene
B) 2-methyl-2-pentene
D) cis-3-methyl-2-pentene
Ans: B
14. Which alcohol below would undergo acid-catalyzed dehydration most readily?
A) A B) B C) C D) D
Ans: D
15. What is the slow, rate-determining step, in the acid-catalyzed dehydration of 2-methyl2-propanol?
A)
B)
C)
D)
Ans:
Protonation of the alcohol to form an oxonium ion.
Loss of water from the oxonium ion to form a carbocation.
Loss of a β-hydrogen from the carbocation to form an alkene.
The simultaneous loss of a β-hydrogen and water from the oxonium ion.
B
Page 3
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
16. Which of the following carbocations is(are) likely to undergo a rearrangement?
A) only I
Ans: D
B) I and III
C) II and III
D) I, II, and III
17. Predict the major product of the following reaction.
A) A B) B C) C D) D
Ans: C
18. Which of the following expressions is the experimentally observed rate law for an E2
reaction of an alkyl halide?
A) rate = k[RX] B) rate = k[RX][base] C) rate = k[RX]2 D) rate = k[base]
Ans: B
19. Which of the following most readily undergoes an E2 reaction with sodium ethoxide
(NaOCH2CH3)?
A) (CH3)3CF B) (CH3)3CCl C) (CH3)3CBr D) (CH3)3CI
Ans: D
Page 4
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
20. How many isomeric alkenes are possible, including stereoisomers, in the following
reaction?
A) two
Ans: B
B) three
C) four
D) five
21. In the dehydrohalogenation of 2-bromobutane, which conformation below leads directly
to the formation of cis-2-butene?
A) only I
Ans: A
B) only II
C) only III
D) I and II
22. Which of the following cannot undergo an E2 reaction?
A) only I
Ans: A
B) only II
C) only III
D) I and III
23. Which of the following would you predict to be the best method for doing the following
conversion with the highest yield?
A) H2SO4, heat
Ans: D
B) NaOCH2CH3
C) H3PO4 D) (1) PBr3 (2) KOC(CH3)3
Page 5
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
24. When a strong base is used in the elimination reaction of an alkyl halide the mechanism,
in general, is
A) E1.
B) E2.
C) E1 for tertiary halides, E2 for primary and secondary halides.
D) E2 for tertiary halides, E1 for primary and secondary halides.
Ans: B
25. Which of the following sets of conditions most favors the E1 mechanism?
A) when the alkyl halide is tertiary and the base is a weak base
B) when the alkyl halide is tertiary and the base is a strong base
C) when the alkyl halide is primary or secondary and the base is a weak base
D) when the alkyl halide is primary or secondary and the base is a strong base
Ans: A
26. Which of the following would have the fastest rate of reaction to form 4-tertbutylcyclohexene?
A) A B) B C) C D) D
Ans: D
Page 6
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
27. What is the first step in the mechanism of the dehydration reaction of a tertiary alcohol
with sulfuric acid to form an alkene?
A) the loss of OH– to form a carbocation
B) the protonation of the hydroxyl group
C) the loss of the proton from the hydroxyl group to give an alkoxide ion
D) the removal of a β-hydrogen from the alcohol
Ans: B
28. Which of the following does not give 1,2-dimethylcyclohexene as one of the acidcatalyzed dehydration products?
A) A B) B C) C D) D
Ans: D
29. Including E-Z isomers, how many E2 products are possible in the following reaction?
A) one B) two
Ans: C
C) three
D) four
30. Which of the following compounds gives a single E2 product on reaction with sodium
ethoxide, NaOCH2CH3?
A) I and II
Ans: B
B) I and III
C) II and III
D) I, II, and III
Page 7
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
31. Which of the following will give 2-methyl-1-butene as the only alkene product on
treatment with KOC(CH3)3 in dimethyl sulfoxide?
A) 2-bromo-3-methylbutane
C) 2-bromo-2-methylbutane
B) 1-bromo-3-methylbutane
D) 1-bromo-2-methylbutane
Ans: D
32. If the following E2 reaction proceeds through an anti-periplanar transition state, what
product or products are expected?
CH3
KOC(CH3)3
(CH3)3COH
Cl
A)
B)
C)
D)
Ans:
only 1-methylcyclohexene
only 3-methylcyclohexene
only 4-methylcyclohexene
equal amounts of 1-methylcyclohexene and 3-methylcyclohexene
B
33. Which of the following stereoisomers gives the exclusive E2 product shown?
A) A B) B C) C D) D
Ans: D
Page 8
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
34. Zaitsev's rule can be used to predict the major product for which of the following
reactions?
A) 2-methylpentane + Br2(with light)
B) 2-bromo-2-methylpentane + NaOCH2CH3 (in ethanol)
C) 2-methyl-2-pentanol + PBr3
D) 2-methyl-2-pentanol + HCl
Ans: B
35. The acid-catalyzed dehydration of the alcohol shown below gives a major product
which results from a carbocation rearrangement. Identify this major product.
A) A B) B C) C D) D
Ans: A
36. Consider the following reaction.
R = –CH3 or –C(CH3)3
Which statement(s) below is(are) correct?
I. X is the major product based on Zaitsev's rule.
II. The X:Y ratio is greater when R = –CH3 than when R = –C(CH3)3.
III. The X:Y ratio is greater when R = –C(CH3)3 than when R = –CH3.
A) I and II B) I and III C) only II D) only III
Ans: A
37. How many different E2 products are expected in the reaction of 3-bromo-1,1dimethylcyclohexane with NaOCH2CH3?
A) only 1 B) 2 C) 3 D) 4
Ans: B
Page 9
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
38. Which one of the following compounds cannot undergo an E2 reaction?
A) 1-bromo-2,2-dimethylbutane
C) 1-bromo-3,3-dimethylbutane
B) 1-bromo-2,3-dimethylbutane
D) 2-bromo-2,3-dimethylbutane
Ans: A
39. What is the major product of the reaction sequence shown below?
A) 2-methyl-1-butene
B) 2-methyl-2-butene
Ans: B
C)
D)
3-methyl-1-butene
2-methylbutane
40. Which of the following compounds gives 4,4-dimethylcyclohexene as the exclusive E2
product?
A) A B) B C) C D) both A and B
Ans: A
41. How many stereoisomers are possible for the following diene?
CH3CH=CHCH2CH2CH=CHCH2CH2CH3
A) only 1 B) two C) three D) four
Ans: D
Page 10
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
42. Based on Zaitsev's rule, which of the following is the major product of the reaction
below?
A) A B) B C) C D) D
Ans: C
43. Which of the alkenes below has the Z-configuration?
CH3
H3CO
A)
CH3
H3C
B)
OCH3
H3C
CH3
CH3
N
C)
H3C
OCH3
H
D)
CH3
H3C
CH2CH3
Cl
CH3
OCH3
A) A B) B C) C D) D
Ans: B
Page 11
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
44. Which alkene of formula C5H10 gives off the least heat (per mol) when burned?
A)
B)
C)
D)
A) A B) B C) C D) D
Ans: B
45. When a C=C is present in a molecule, what is the minimum number of atoms that must
lie in a single plane?
A) 2 B) 4 C) 6 D) 8
Ans: C
46. If you wanted to make compound III, starting with compound I or II, what would you
do?
OH
?
I
Br
A)
B)
C)
D)
Ans:
III
?
II
React I with H2SO4.
React II with NaOEt.
Either of the reactions in A or B above would work.
Neither of the reactions in A or B above would work.
B
Page 12
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.
Chapter 5 Structure and Preparation of Alkenes - Elimination Reactions: Answers
Prof. Sivaguru Jayaraman
47. Which compound would react slowest with KOtBu?
Br
Br
D
D
A
B
Br
Br
D
C
D
D
A) A B) B C) C D) D
Ans: A
48. Which reagent accomplishes the following?
Cl
OH
?
A) HCl
Ans: C
B) Cl2, light
C) SOCl2
D) NaCl
49. What would be the proper name of the molecule below?
A) (E)-2-ethyl-2-butene
B) (Z)-3-methyl-3-pentene
Ans: C
C)
D)
(E)-3-methyl-2-pentene
(Z)-2-isohexene
Page 13
Chem 341: Organic Chemistry, Prof. Sivaguru Jayaraman, Fall 2010.