UNIVERSITETET I OSLO
Det matematisk-naturvitenskapelige fakultet
Exam in:
KJM3000 and KJM4000
Day of exam:
2007-06-07
Exam hours:
14.30 – 17.30 ( 3hours)
This examination paper consists of 2 page(s).
Appendices:
3 (3, 2 and 3 pages respectively)
Permitted materials: Ruler and calculator
Make sure that your copy of this examination paper
is complete before answering.
Question 1 (20%)
O
O
O
N
O
1
Compound 1 has been synthesised. Identification of 1 has been done by spectroscopic
techniques. Below are listed a selection of NMR-data (The list does not include all H’s and
C’s in the molecule).
(300 MHz; CDCl3): δ 2.13 (dd, 1H, J = 9.0 og 6.2 Hz), 2.15 (s, 3H), 3.10 (dd, 1H, J
= 6.2 og 5.9 Hz), 3.68 (s, 3H), 3.80 (dd, 1H, J = 9.0 og 5.9 Hz)
13C-NMR (75MHz, CDCl ): δ 17.0 (CH ), 21.0 (CH ), 33.8 (C), 36.8 (CH) 52.7 (CH ).
3
2
3
3
1H-NMR
a)
Calculate the accurate m/z value for M+· from a high resolution mass spectrum of 1.
Conditions: (EI, 70 eV).
b)
If you record the IR spectrum of 1, you would expect three strong stretching
frequencies at approx. 1715, 1740 and 1785 cm-1. Identify the functional groups which
give rise to the three frequencies? Give a short explanation
c)
Identify (circle) the chromophore in 1 which is expected to lead to the highest ε and
λmax values in a UV spectrum of 1? Give a short explanation.
d)
Assign the listed 1H-NMR-signals of 1 to the structure and give a short explanation of
the coupling pattern.
e)
Assign the listed 13C-NMR-signals of 1 to the structure.
Question 2 (40%)
An “unknown” compound has been studied spectroscopically. Propose a molecular structure
for the “unknown” compound based on the spectroscopic data found in attachment 2. Assign
as many of the signals in the 13C- and 1H-NMR spectra as possible and give a brief
explanation for your assignments. Draw equations to account for the fragmentation reactions
which produce the indicated fragments.
Question 3 (40%).
An “unknown” compound has been studied spectroscopically. Propose a molecular structure
for the “unknown” compound based on the spectroscopic data found in attachment 3. Assign
as many of the signals in the 13C- and 1H-NMR spectra as possible and give a brief
explanation for your assignments. Draw equations to account for the fragmentation reactions
which produce the indicated fragments. A HRMS spectrum of the unknown gave m/z =
84.0577 ± 0.0005 for M+·. Briefly explain the difference between the two IR spectra (in
attachment 3) in the area above 3000 cm-1.
Vedlegg 1 / Attachment 1
Vedlegg 2 / Attachment 2
Grunnstoff analyse / Elemental analysis: C = 44.8 %, H = 3.27 %
1
H-NMR: 90 MHz, 42mg in 0.5 ml CDCl3
δ: 10.6 (1H, s), 7.44 (2H, d, J = 8 Hz), 7.15 (2H, d, J = 8 Hz), 3.58 (2H, s)
13
C-NMR: Broadband decoupled, 25MHz, 350 mg in 1.5 ml CDCl3
δ: 177.7, 132.1, 131.7, 131.1, 121.5, 40.4.
IR: KBr disc.
MS: EI, 75 eV.
Vedlegg 3 / Attachment 3
Masseformel basert på nøyaktig masse fra de mest naturlig forekommende isotoper.
Formula mass based on the accurate mass of the most abundant isotopes.
1
H-NMR: 400 MHz, 0.5 ml in 0.5 ml CDCl3
δ: 4.33 (1H, m), 3.53 (1H, s), 2.48 (1H, s), 1.78 – 1.70 (2H, m), 1.01 (3H, t)
13
C-NMR: Broadband decoupled, 15 MHz, 20 volume % in CDCl3
δ: 85.0, 72.9, 63.4, 30.7, 9.4.
IR: Liquid film
IR: Gas phase
MS: EI, 70 eV