CH223 ORGANIC CHEMISTRY II
QUIZ 1
25 September 2008
Time allowed: 80 minutes
Attempt all 35 questions by writing answers for each question on the grid answer sheet provided
1. In conventional mass spectrometry, what is being detected?
A.
The molecular weight of the compound
B.
The molecular formula of the compound
C.
The mass of any cationic species
6. Which of the following statements is (are) accurate about the IR
spectrum of compounds A, B, and C below?
D. The mass of any neutral species
2. You observe a compound that exhibits a mass spectrum with
peak at 160 and a peak at 162, both of equal intensity. This
compound contains
A.
Compound A shows absorptions at 3000 and 1700 cm-1.
B.
Compound B show absorptions at 3200-3600 and 1650 cm1.
A.
C.
two chlorines.
B.
one iodine.
C.
one bromine.
Compound C show absorptions at 3200-3600 and 3000 cm1.
D. Both (Compound A shows absorptions at 3000 and 1700
cm-1) and (Compound B show absorptions at 3200-3600
D. two bromines.
and 1650 cm-1) are true.
3. What type(s) of molecular motion is (are) observed using
E.
infrared spectroscopy?
Statements (Compound A shows absorptions at 3000 and
1700 cm-1), (Compound B show absorptions at 3200-3600
A.
and 1650 cm-1), and (Compound C show absorptions at
Stretching and bending
B.
Rotation and excitation
C.
Spin flipping
D. Fragmentation
3200-3600 and 3000 cm-1) are all true.
7.
Which of the circled C-H bonds absorbs at the highest wave
number in the IR spectrum?
4. Compared to a C-H bond, a C-D bond will vibrate where in the
infrared spectrum?
A.
Higher molecular weight
B.
Lower molecular weight
C.
Lower wavenumbers
D. Higher wavenumbers
5. Why is the infrared absorption for the stretching motion of
internal alkynes rarely observed?
A.
B.
B
C.
C
D. D
E.
A.
A
E
They do not form cations.
B.
They are too strong.
C.
There must be a change in dipole.
D. They don't have hydrogens.
1
8. You are given a bottle of an organic liquid and told it must be
either cyclohexane or 1-hexene. Which of the following
10. What type of signals would you observe in the mass and/or
infrared spectrum of the following compound?
statements is (are) true about these two compounds?
A.
A. The two compounds can be differentiated by their mass
spectra because they will have molecular ions at different
masses.
B.
1-hexene will show an absorption at 1650 cm-1 but
A signal at 96 amu
B.
Two signals at 112 and 114 amu
C.
A signal at 1600 cm-1
D. A signal at 1715 cm-1
11. How many different kinds of protons are present in each of the
following compounds?
cyclohexane will not.
C.
Both cyclohexane and 1-hexene will show C-H
absorptions at about 3000 cm-1.
D. Statements (1-Hexene will show an absorption at 1650
12. Into how many peaks will each of the circled protons be split?
cm-1 but cyclohexane will not) and (Both cyclohexane
and 1-hexene will show C-H absorptions at about 3000
cm-1) are both true.
E.
Statements (The two compounds can be differentiated by
their mass spectra because they will have molecular ions
at different masses), (1-Hexene will show an absorption
at 1650 cm-1 but cyclohexane will not), and (Both
cyclohexane and 1-hexene will show C-H absorptions at
about 3000 cm-1) are all true.
9. Which of the following statements is (are) true about a
compound that has a molecular ion in its mass spectrum at
13. How many different kinds of protons are present in each of the
following molecules?
mass 170 and 172, and shows prominent peaks in its IR
spectrum at 3150-3000 and 1600 cm-1?
A.
The compound is not pure.
B.
The compound contains a halogen.
C.
The compound contains an OH group and sp2 hybridized
C-H bonds.
D. Both (The compound is not pure) and (The compound
contains a halogen) are true statements.
E.
Both (The compound is not pure) and (The compound
contains an OH group and sp2 hybridized C-H bonds) are
true statements.
2
14. Which of the labeled hydrogens absorbs furthest upfield in the
NMR?
19. How could spectroscopy be used to distinguish between the
following compounds?
A.
15. Which of the circled protons in the molecules below would
absorb furthest downfield in the NMR?
Compound A has a triplet in the NMR at 1.0.
B.
Compound B has a peak at 3200-3000 cm-1 in the IR.
C.
Compound A has a peak in the IR at 3000 cm-1.
D. Compound A has a triplet in the NMR at 1.0 and
compound B has a peak at 3200-3000 cm-1 in the IR.
E.
Compound B has a peak at 3200-3000 cm-1 in the IR and
compound A has a peak in the IR at 3000 cm-1.
20. . What region of the electromagnetic spectrum does nuclear
16. Into how many peaks will the circled proton be split?
magnet resonance spectroscopy use?
A.
Radio frequency
B.
Microwave frequency
C.
Infrared frequency
D. Visible frequency
17. .For each of the following compounds, indicate how many 13C
NMR signals it will show.
E.
Ultraviolet frequency
21. Which of the following statements is true about electromagnetic
radiation?
A.
All molecules will absorb electromagnetic radiation at
some frequency.
18. An unknown compound X has the empirical formula C3H6O
and a molecular ion in its mass spectrum at 116. Compound X
shows no IR absorption at 3200-3600 cm-1 but shows a peak at
1700 cm-1. The NMR spectral data of X is shown below. What
is the structure of compound X?
B.
Frequency is directly proportional to wavelength.
C.
NMR uses the microwave region of the electromagnetic
spectrum.
D. The radio frequency region of the electromagnetic spectrum
has the largest energy per photon.
E.
Energy is inversely proportional to frequency.
22. Which of the following statements is (are) true about free radical
halogenation of alkanes?
A.
The first of the chain-propagating steps is rate-
determining.
3
B.
The reaction proceeds by way of a flat sp2 hybridized free
26. A possible reaction of ethane with chlorine:
radical.
C.
The chain-initiating step involves cleavage of a carbonhydrogen bond to afford a carbon radical and a hydrogen
atom.
D. Statements (The first of the chain-propagating steps is
from the mechanism in problem 25, Determine H for step [2].
Bond dissociation energies (kcal/mole):
rate-determining) and (The reaction proceeds by way of a
flat sp2 hybridized free radical) are both true.
E.
Statements (The first of the chain-propagating steps is
rate-determining), (The reaction proceeds by way of a
flat sp2 hybridized free radical), and (The chain-initiating
step involves cleavage of a carbon-hydrogen bond to
afford a carbon radical and a hydrogen atom) are all true.
23. Arrange the following radicals in order of decreasing stability
A.
-5
B.
+58
C.
-28
D. + 23
E.
24. Which of the labeled hydrogens is most easily abstracted in a
free radical bromination reaction?
None of the choices are correct.
27. A synthesis of the epoxide below can be completed in 3 steps
starting with chemistry of the indicated starting material. Select
a reasonable route to complete the synthesis.
A. (1) Br2,, h; (2) KOH, Ethanol; (3) peracetic acid
B. (1) Br2,, heat; (2) H2SO4; (3) peracetic acid
25. Draw a plausible reaction mechanism for the following reaction.
C. (1) HBr, peroxides; (2) H2SO4; (3) peracetic acid
A.
A
B.
B
C.
C
28. What is the missing reagent in the reaction below?
A.
NBS
B.
HBr/ ROOR
C.
HBr/ heat
4
29. Which of the following reactions does not proceed to form a
haloalkane?
31-35. Determine the structures for each problems with given
information.
31. For C5H10 O
A.
A
B.
B
C.
C
32. For C7H8
D. D
30. Select the major product in the following reaction.
33. M.W. =60.1
A.
A
B.
B
C.
C
D. D
E.
E
5
34.
6
35. 13C NMR shows peaks at 207.1, 172.0, 59.2, 46.6, 24.2, 13.2
7
CH223 QUIZ 1 ANSWER GRID
Name………………………..
Student Number………………………
1
2
3
4
5
C
C
A
C
C
6
7
8
9
10
D
B
D
B
D
11
12
6, 4, 6
3, 8, 2, 4, 4
13
14
15
B
4, 5, 5, 4, 3
He
16
17
7
5, 4, 7, 3
19
20
B
A
24
26
Hb
A
27
28
A
B
29
30
D
B
18
21
22
A
D
23
b>a>e>d>c
25
31
32
34
35
33
Total Score
8
9