Organic Chemistry
I need a clear step by step solution for this worksheet. for example : the answer is 2.2, how did you get the answer ?Â
“Practice exam questions” for the Midterm Exam
Unit 1
1. What is the degree of unsaturation for a compound whose molecular formula is C14H17NOS? 2. What is the wavenumber (with appropriate units) of radiation that
has a frequency of 9.96 x 1013 Hz?
3. What is the frequency (with appropriate units) of radiation that has a corresponding wavenumber of 12000 cm-1?
4. Which one of the following statements is correct? Please check ( ) your selection.
B
P(CH3)2
A Si(CH3)3
! The IR absorption band due to bond A will be more intense than the IR absorption band due to bond B ! The IR absorption band due to bond A will be less intense than
the IR absorption band due to bond B
5. Which one of the following statements is correct? Please check ( ) your selection. ! The absorption band due to a C=Si bond occurs at a smaller wavenumber than
the absorption band due to a C=Ge bond ! The absorption band due to a C=Si bond occurs at a larger wavenumber than the absorption band due to a C=Ge bond
6. Draw a plausible structure for a compound whose molecular formula is C7H10O that is consistent with the information provided below. Bromine test positive Complete
set of IR absorption bands 2992 cm-1 (sharp, medium) 1705 cm-1 (sharp, strong) 1642 cm-1 (sharp, medium)
7. The molecular formula of compound C is C5H8. IR data for compound C is provided below. Treatment of compound C with excess hydrogen gas (in the presence of a
suitable metal catalyst) gives a compound whose molecular formula is C5H10. Draw a plausible structure for compound C.
Complete set of IR absorption bands 3004 cm-1 (sharp, medium) 2993 cm-1 (sharp, medium) 1681 cm-1 (sharp, medium)
3 of 17 | P a g e
8. The molecular formula of compound D is C6H10. IR data for compound D is provided below. Draw a plausible structure for compound D.
Complete set of IR absorption bands 3305 cm-1 (sharp, medium) 2997 cm-1 (sharp, medium) 2191 cm-1 (sharp, weak)
9. The molecular formula of compound E is C7H10O2. IR data for compound E is provided below. Draw a plausible structure for compound E. Bromine test Positive
Complete set of IR absorption bands 3005 cm-1 (sharp, medium) 2918 cm-1 (sharp, medium) 1709 cm-1 (sharp, strong) 1653 cm-1 (sharp, medium) 1243 cm-1 (sharp, strong)
1054 cm-1 (sharp, strong)
10. The molecular formula of compound F is C10H11NO. IR data for compound F is provided below. Draw a plausible structure for compound F. Bromine test Negative
Complete set of IR absorption bands 3302 cm-1 (broad, strong) 3008 cm-1 (sharp, medium) 2994 cm-1 (sharp, medium) 2210 cm-1 (sharp, medium) 1501 cm-1 (sharp, medium)
1247 cm-1 (sharp, medium)
Unit 2
1. A signal has been reported to occur 5000 Hz downfield from TMS in an NMR spectrometer operating at 500 MHz. What is the chemical shift (with appropriate units) of
this signal on the delta scale?
2. Which of the following statements are correct? Please check ( ) your selection.
a) b)
H O CH3 Br H CH3 H
H
CH3
! The circle protons are chemically equivalent ! The circle protons are not chemically equivalent
! The circle protons are chemically equivalent ! The circle protons are not chemically equivalent
4 of 17 | P a g e
3. For each of the following compounds label the various sets of chemically equivalent protons.
e.g.
O
H
H
H
4. Using the approach/notation/data presented in lecture what are the predicted chemical shifts (in ppm) of the circled protons? Please show your work.
H O H
H H
O OH
NC C
S
C CCH2CH2OH
CH3O C C
OCH2CH2SH
O
5. What type of signals (singlet, doublet, triplet, quartet, etc) will the circled protons give rise to?
O Cl CH3 H CH3
CH2Br H O
H C C C C H
OCH3
H
CH3 H
H
CH2Br
OCH3
6. A proton NMR spectrum exhibits signals at 5.0 ppm and 9.0 ppm. The operating frequency of the spectrometer is 200 MHz. Complete the following statement with the
appropriate numerical values.
The two peaks are separated by Hz.
The peak at ppm is more upfield than the peak at ppm.
5 of 17 | P a g e
7. Which one of the following statements is correct? Please check ( ) your selection.
! Proton HC is more shielded than proton HD ! Proton HC is less shielded than proton HD ! Protons HC and HD are equally shielded
8. Which one of the following statements is correct? Please check ( ) your selection.
! The Beffective sensed by proton HE is smaller than the Beffective sensed by proton HF ! The Beffective sensed by proton HE is larger than the Beffective sensed by
proton HF ! None of the above
9. A certain segment of an unknown compound’s proton NMR spectrum contains peaks K and L. Given that peak L corresponds to two protons how many protons does peak K
correspond to?
K
L
6 of 17 | P a g e
10. Which compound is responsible for Spectrum A? Which compound is responsible for Spectrum B? Briefly outline your reasoning.
7 of 17 | P a g e
11. Which compound is responsible for Spectrum C? Which compound is responsible for Spectrum D? Briefly outline your reasoning.
8 of 17 | P a g e
12. Which compound is responsible for Spectrum E? Which compound is responsible for Spectrum F? Briefly outline your reasoning.
S
S
Compound Q Compound R
SPECTRUM E 6H
2H 3H
3H
3H
1H
8 7 6 5 4 3 2 1 0 PPM
9 of 17 | P a g e
SPECTRUM F 3H
6H
3H
3H
2H
1H
8 7 6
5 4 PPM
septet 3 2 1 0
10 of 17 | P a g e
13. Which compound is responsible for Spectrum J? Which compound is responsible for Spectrum K? Briefly outline your reasoning.
N N
Compound S Compound T
SPECTRUM J 6H
3H 3H
3H
2H
4H
1H 1H 1H 1H
8 7 6 5 4 3 2 1 0 PPM
octet
11 of 17 | P a g e
SPECTRUM K
doublet (6H)
triplet (3H)
3H
1H 1H
2H 4H 2H
2H
1H
8 7 6 5 4 PPM
3 2 1 0
octet
12 of 17 | P a g e
14. Which one of the following statements is correct?
! Spectra I, II and III are due to compounds U, V and W respectively ! Spectra I, II and III are due to compounds U, W and V respectively ! Spectra I, II and III are
due to compounds V, U and W respectively ! Spectra I, II and III are due to compounds V, W and U respectively ! Spectra I, II and III are due to compounds W, U and V
respectively ! Spectra I, II and III are due to compounds W, V and U respectively
N
N
N
Compound U Compound V Compound W
SPECTRUM I 6H
2 quartets (2H each)
2 triplets (3H each)
3H (phenyl protons)
8 7 6 5 4 3 2 1 0 PPM
13 of 17 | P a g e
SPECTRUM II 6H
3H
6H
3H (phenyl protons)
1H (septet)
8 7 6 5 4 3 2 1 0 PPM
SPECTRUM III 6H
6H
3H (phenyl protons) 4H
7 6 5 4 3 2 1 0 PPM
14 of 17 | P a g e
Unit 3
1. Draw the major organic product(s) of the following reactions. Don’t forget to use wedge/dash notation where appropriate. If no reaction is expected write NR.
i.
CH3 D2O
H C
CH3
CH2MgBr CH3CH2CH2OH
ii.
Br 1. Mg, dry diethyl ether, heat
CH3
2. H2O
2. Draw the major organic product(s) of the following reactions. Don’t forget to use wedge/dash notation where appropriate. If no reaction is expected write NR.
i.
Cl + Mg
dry diethyl ether,
heat
ii.
CH2MgBr
CH3
C CH
dry THF
3. Give a balanced chemical equation, with appropriate solvent, for the preparations of the following compounds.
CH2Li MgCl
15 of 17 | P a g e
Unit 4
1. Draw the major organic product(s) of the following reactions. Please be careful to use wedge/dash notation where appropriate. If no reaction is expected write
NR.
i.
HO H
PCl3, pyridine
ii.
OH
CH3
CH3 H2SO4, heat
2. Draw the major organic product(s) of the following reactions. Please be careful to use wedge/dash notation where appropriate. If no reaction is expected write
NR.
i.
MsCl, pyridine
OH
ii.
OH
HBr
3. Draw the major organic product(s) of the following reactions. Please be careful to use wedge/dash notation where appropriate. If no reaction is expected write
NR.
i.
OH PCC, dry CH2Cl2
ii.
HCl
OH
16 of 17 | P a g e
4. Draw the major organic product(s) of the following reactions. Please be careful to use wedge/dash notation where appropriate. If no reaction is expected write
NR.
i.
O
OH
H3C S Cl O
OH
(1 mole)
(1 mole)
in pyridine
ii.
H2SO4, heat
OH
5. Provide the structures of compounds A and B in the spaces provided below. Please be careful to use wedge/dash notation where appropriate.
OH
PBr3, pyridine
NaCN, A B DMSO, heat
6. Draw the major organic product(s) of the following reactions. Please be careful to use wedge/dash notation where appropriate. If no reaction is expected write
NR.
i.
O
H aqueous H2CrO4
ii.
CH3 C OH
H2SO4, heat
CH3
17 of 17 | P a g e
7. Draw the major organic product(s) of the following reactions. Please be careful to use wedge/dash notation where appropriate. If no reaction is expected write
NR.
i.
CH3CH2CH2OH
ii.
HBr
OH
excess aq H2CrO4
HO
8. Which one of the following statements is correct?
H N N
C D
! Compound D arose from the oxidation of compound C ! Compound D arose from the reduction of compound C ! The conversion of compound C to compound D did not involve a
redox reaction
9. Which one of the following statements is correct?
O O
H CH3
E F
! Compound F arose from the oxidation of compound E ! Compound F arose from the reduction of compound E ! The conversion of compound E to compound F did not involve a
redox reaction
