Solapur University Question Paper
M.Sc. (Part – II) (Semester – III) Examination, 2014
ORGANIC CHEMISTRY
Advanced Spectroscopic Methods (Paper – X)
Day and Date : Wednesday, 23-4-2014 Total Marks : 70
Time : 3.00 p.m. to 6.00 p.m.
Instructions : 1) Attempt in all five questions.
2) Section I is compulsory.
3) Attempt any two questions from Section II and any two from
Section III.
4) Answers to all questions (Sections I, II and III) should be
written in the one answer book.
5) All questions carry equal marks.
6) Figures to the right indicate full marks.
7) Use of log table and calculators is allowed.
SECTION – I
1. A) Select the correct answer for each of the following : 4
i) Which of the following compound would be expected to absorb light of
longest wave length ?
a) b)
c) d)
ii) How many 1HNMR signals would you expect for H2C = C = CH2 ?
a) 1 b) 2
c) 3 d) 0
SLR-VD – 10 -2-
iii) A cyclic compound of molecular formula C6H10 shows only two signals
in the broad-band decoupled 13C NMR spectrum. The off resonance
decoupled spectrum showed a triplet and doublet. The compound is
a) b)
c) d)
iv) An aromatic hydrocarbon (M = 134) has an intense ion at m/e 91. Which
of the following is consistent with the data ?
a) 1, 4-Diethylbenzene b) n-Butylbenzene
c) 1, 2, 4, 5- Tetramethylbenzene d) 1-Isopropyl-4-methylbenzene
B) Fill in the blanks : 4
i) Each alkyl group produces a bathochromic shift of _____________ when
present on a diene.
ii) The long range coupling constants are usually ______________
iii) The carbonyl carbon of cyclohexanone appears at δ 210 relative to other
carbons due to _____________ in its 13CNMR spectrum.
iv) According to the nitrogen rule if M+ is even, then the compound will contain
an _____________ number of nitrogen atoms.
C) Solve the followings : 6
i) How are (E) and (Z)-2-butene differentiated by proton NMR spectroscopy ?
ii) What are the functional group and finger print region in IR spectrum ?
iii) The UV band of ethylene at λmax175 nm is shifted to λmax217 in 1, 3-
butadiene but remains unchanged in 1, 5-hexadiene. Explain.
iv) What are Lanthanide shift reagents ?
v) Suggest the structure for a hydrocarbon C5H12 with one1HNMR and two
13CNMR peaks.
vi) In 1-propanol the base peak is at 2
m = 31, in allyl alcohol, however it is
at 2
m = 57. Explain.
-3- SLR-VD – 10
SECTION – II
2. A) An organic compound with the molecular formula C8H8N2O3 shows the following
spectral data. Assign the values and deduce the structure of the compound
UV ( ) λmax nm : 225, 335
IR (cm–1) : 3279, 2920, 1683, 1508 and 1462
1HNMR (δ) ppm : 2.1(s, 3H); 7.85 (d, 2H; J = 7.5Jz)
8.25 (d, 2H, J = 7.5 Hz) and 10.6
(brs, 1H)
13CNMR (δ) ppm : 24 (q), 115(d), 122 (d), 123 (s),
171 (s) and 194 (s). 7
B) Draw the Karplus curve and explain its significance. 7
3. A) What is ortho effect in mass spectroscopy ? Explain how it is reflected in the
mass spectral fragmentation of ortho and p-nitro toluenes. 7
B) How are the following pairs of compounds differentiated by the suggested
methods ?
i) 1, 3, 5- Trinitrobenzene and 1, 2, 3-trinitrobonzene by 13CNMR
spectroscopy.
ii) Acetanilide and N-methylbenzamide by IR.
iii) and by UV spectroscopy. 7
4. A) How can the following reaction monitored with the assistance of IR spectra of
the compounds ? Justify your answer. 7
B) Discuss the principle and applications of FT-13CNMR spectroscopy. 7
SLR-VD – 10 -4-
SECTION – III
5. A) Describe the shielding and deshielding mechanisms in NMR. 5
B) How would you distinguish between the reactant and product using DEPT
NMR ? Explain taking proper example. 5
C) Two isometric compounds I and II having molecular formula C3H6O display
IR absorption at (I) ~ 1710 cm–1 (II) 3300 and 1640 cm–1. Predict the structure
of I and II based on the above data. 4
6. A) Explain the mechanism of spin-spin splitting and the rules for first order splitting
in 1HNMR. 5
B) An organic compound (C9H10O2) has a strong band in the IR spectrum at
1690 cm–1. Its PMR spectrum shows the following signals. Identify the
compound and interpret the spectral data δ2.5 (Sδ 3H); 3.9 (S, 3H); 7.0 (d,
2H, J = 12 Hz); 8.1 (d, 2H, J = 12 Hz.) 5
C) Taking appropriate example explain the utility of HRMS in determining the
exact molecular formulae. 4
7. Write a note on (any three) : 14
A) Nuclear Overhauser effect
B) Study of H-bonding by IR spectroscopy
C) Cosy spectroscopy
D) McLafferty rearrangement.
_____________________
M.Sc. (Part – II) (Semester – III) Examination, 2014
ORGANIC CHEMISTRY
Advanced Spectroscopic Methods (Paper – X)
Day and Date : Wednesday, 23-4-2014 Total Marks : 70
Time : 3.00 p.m. to 6.00 p.m.
Instructions : 1) Attempt in all five questions.
2) Section I is compulsory.
3) Attempt any two questions from Section II and any two from
Section III.
4) Answers to all questions (Sections I, II and III) should be
written in the one answer book.
5) All questions carry equal marks.
6) Figures to the right indicate full marks.
7) Use of log table and calculators is allowed.
SECTION – I
1. A) Select the correct answer for each of the following : 4
i) Which of the following compound would be expected to absorb light of
longest wave length ?
a) b)
c) d)
ii) How many 1HNMR signals would you expect for H2C = C = CH2 ?
a) 1 b) 2
c) 3 d) 0
SLR-VD – 10 -2-
iii) A cyclic compound of molecular formula C6H10 shows only two signals
in the broad-band decoupled 13C NMR spectrum. The off resonance
decoupled spectrum showed a triplet and doublet. The compound is
a) b)
c) d)
iv) An aromatic hydrocarbon (M = 134) has an intense ion at m/e 91. Which
of the following is consistent with the data ?
a) 1, 4-Diethylbenzene b) n-Butylbenzene
c) 1, 2, 4, 5- Tetramethylbenzene d) 1-Isopropyl-4-methylbenzene
B) Fill in the blanks : 4
i) Each alkyl group produces a bathochromic shift of _____________ when
present on a diene.
ii) The long range coupling constants are usually ______________
iii) The carbonyl carbon of cyclohexanone appears at δ 210 relative to other
carbons due to _____________ in its 13CNMR spectrum.
iv) According to the nitrogen rule if M+ is even, then the compound will contain
an _____________ number of nitrogen atoms.
C) Solve the followings : 6
i) How are (E) and (Z)-2-butene differentiated by proton NMR spectroscopy ?
ii) What are the functional group and finger print region in IR spectrum ?
iii) The UV band of ethylene at λmax175 nm is shifted to λmax217 in 1, 3-
butadiene but remains unchanged in 1, 5-hexadiene. Explain.
iv) What are Lanthanide shift reagents ?
v) Suggest the structure for a hydrocarbon C5H12 with one1HNMR and two
13CNMR peaks.
vi) In 1-propanol the base peak is at 2
m = 31, in allyl alcohol, however it is
at 2
m = 57. Explain.
-3- SLR-VD – 10
SECTION – II
2. A) An organic compound with the molecular formula C8H8N2O3 shows the following
spectral data. Assign the values and deduce the structure of the compound
UV ( ) λmax nm : 225, 335
IR (cm–1) : 3279, 2920, 1683, 1508 and 1462
1HNMR (δ) ppm : 2.1(s, 3H); 7.85 (d, 2H; J = 7.5Jz)
8.25 (d, 2H, J = 7.5 Hz) and 10.6
(brs, 1H)
13CNMR (δ) ppm : 24 (q), 115(d), 122 (d), 123 (s),
171 (s) and 194 (s). 7
B) Draw the Karplus curve and explain its significance. 7
3. A) What is ortho effect in mass spectroscopy ? Explain how it is reflected in the
mass spectral fragmentation of ortho and p-nitro toluenes. 7
B) How are the following pairs of compounds differentiated by the suggested
methods ?
i) 1, 3, 5- Trinitrobenzene and 1, 2, 3-trinitrobonzene by 13CNMR
spectroscopy.
ii) Acetanilide and N-methylbenzamide by IR.
iii) and by UV spectroscopy. 7
4. A) How can the following reaction monitored with the assistance of IR spectra of
the compounds ? Justify your answer. 7
B) Discuss the principle and applications of FT-13CNMR spectroscopy. 7
SLR-VD – 10 -4-
SECTION – III
5. A) Describe the shielding and deshielding mechanisms in NMR. 5
B) How would you distinguish between the reactant and product using DEPT
NMR ? Explain taking proper example. 5
C) Two isometric compounds I and II having molecular formula C3H6O display
IR absorption at (I) ~ 1710 cm–1 (II) 3300 and 1640 cm–1. Predict the structure
of I and II based on the above data. 4
6. A) Explain the mechanism of spin-spin splitting and the rules for first order splitting
in 1HNMR. 5
B) An organic compound (C9H10O2) has a strong band in the IR spectrum at
1690 cm–1. Its PMR spectrum shows the following signals. Identify the
compound and interpret the spectral data δ2.5 (Sδ 3H); 3.9 (S, 3H); 7.0 (d,
2H, J = 12 Hz); 8.1 (d, 2H, J = 12 Hz.) 5
C) Taking appropriate example explain the utility of HRMS in determining the
exact molecular formulae. 4
7. Write a note on (any three) : 14
A) Nuclear Overhauser effect
B) Study of H-bonding by IR spectroscopy
C) Cosy spectroscopy
D) McLafferty rearrangement.
_____________________
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