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8/13/2019 2D-NMR-Athar-P-1 (1)
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1
2D-
NUCLEAR MAGNETIC RESONANCESPECTROSCOPY
Part-1
Dr. M. Athar Abbasi
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THE PRINCIPLE OF 2D-NMR SPECTROSCOPY
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GENERAL SCHEME FOR 2D-NMR
In 1D pulsed Fourier transform NMR the signal is recorded as a
function of one time variable and then Fourier transformed to givea spectrum which is a function of one frequency variable.
In 2D-NMR the signal is recorded as a function of two time
variables, t1
and t2
, and the resulting data Fourier transformed
twice to yield a spectrum which is a function of two frequency
variables.
The general scheme for two dimensional spectroscopy is
In the first period, called the preparation time, the sample is excited by one or more pulses. The resulting magnetization isallowed to evolve for the first time period, t1
.
Then another period follows, called the mixing time, which
consists of a further pulse or pulses. After the mixing period thesignal is recorded as a function of the second time variable, t2.
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This sequence of events is called a pulse sequence and the exact
nature of the preparation and mixing periods determines theinformation found in the spectrum.
It is important to realize that the signal is not recorded during the
time t1
, but only during the time t2
at the end of the sequence. The
data is recorded at regularly spaced intervals in both t1
and t2
.
The two-dimensional signal is recorded in the following way. First,
t1
is set to zero, the pulse sequence is executed and the resulting
free induction decay recorded. Then the nuclear spins are allowed
to return to equilibrium. t1
is then set to 1, the sampling interval
in t1
, the sequence is repeated and a free induction decay is
recorded and stored separately from the first. Again the spins are
allowed to equilibrate, t1
is set to 2 1, the pulse sequence
repeated and a free induction decay recorded and stored. Thewhole process is repeated again for t1
= 3 1, 4 1 and so on until
sufficient data is recorded, typically 50 to 500 increments of t1
.
Thus recording a two-dimensional data set involves repeating a
pulse sequence for increasing values of t1
and recording a free
induction decay as a function of t2 for each value of t1.
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TWO-DIMENSIONAL NMR PULSE SEQUENCE
Fig. 2D J-Resolved NMR spectroscopy; the evolution time t1 is gradually
increased while the detection time t2 is kept constant.
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Fig. Basic pulse sequence for 2D acquisition
2D Fourier transformThe FID is then Fourier transformed in both directions (fig. 2) to
yield the spectrum. The spectrum is conventionally displayed as a
contour diagram. The evolution frequency is labeled f 1 and the
acquisition frequency is labeled f 2 and plotted from right to left.
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PLOTTING 2D-NMR SPECTRUM
Conventional NMR spectra (1D-
spectra) are plots of intensity vs.
frequency; in 2D- spectroscopy intensity is plotted as a functionof two frequencies, usually called F1
and F2
.
There are various ways of representing such a spectrum on paper,
but the one most usually used is to make a contour plot in which the intensity of the peaks is represented by contour lines drawn at
suitable intervals, in the same way as a topographical map.
The position of each peak is specified by two frequency co-
ordinates corresponding to F1 and F
2
.
2D-NMR spectra are always arranged so that
the F2
co-ordinates of the peaks correspond
to those found in the normal 1D-
spectrum,
and this relation is often emphasized byplotting the 1D-
spect. alongside the F2
axis.
The figure shows a schematic COSY
spectrum of a hypothetical moleculecontaining just two protons, A and X, which
are coupled together.
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The one-dimensional spectrum is plotted alongside the F2
axis,
and consists of the familiar pair of doublets centred
on the
chemical shifts of A and X, δA and δX
respectively.
In the COSY spectrum, the F1
co-ordinates of the peaks in the two-
dimensional spectrum also correspond to those found in the normal one-dimensional spectrum and to emphasize this point theone dimensional spectrum has been plotted alongside the F1 axis.
It is immediately clear that this COSY spectrum has some
symmetry about the diagonal F1
= F2
which has been indicated
with a dashed line.
In a 1D-
spectrum scalar couplings give rise to multiplets
in the
spectrum. In 2D-
spectra the idea of a multiplet
has to be
expanded somewhat so that in such spectra a multiplet
consists
of an array of individual peaks often giving the impression of a
square or rectangular outline.
The appearance in a COSY spectrum of a cross-peak multiplet
F1
=
δA, F2 = δX indicates that the two protons at shifts δA and δX havea scalar coupling between them.
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ADVANCED NMR TECHNIQUES
ONE DIMENSIONAL NMR TECHNIQUES
DEPT [Distortionless Enhancement (of NMR Signals) byPolarization Transfer]A procedure which enhances the intensities of 13C signals and
also provides information on the number of attached protons.
Quaternary carbons are not observed. The 135o
pulse results inpositive signals for CH and CH3
groups and negative signals for
CH2
groups. The 90o
pulse results in positive signals for CH
groups and null signals for CH2
and CH3
groups. The 45o
pulse
results in positive signals for CH, CH2
and CH3
groups.
INEPT
(Insensitive Nuclei Enhanced by Polarization Transfer)
A precursor to DEPT that gives similar results, although often not
as well.
NOE
(Nuclear Overhauser
Enhancement)
Irradiation at specific frequencies before signal aquisition
enhances the intensities of nearby nuclei. Nearby nuclei inducerelaxation, which leads to signal enhancement, through dipole- dipole interactions. The effect usually diminishes as a function
of
1/r6.
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TWO DIMENSIONAL NMR TECHNIQUES
NOESY
(Nuclear Overhauser
Enhancement Spectroscopy)
The 2D version of the NOE experiment yields a display of all
atoms that are close in space. The diagonal and the projection on
each axis are the one-dimensional spectrum. The off-diagonal
peaks indicate Overhauser
Enhancements between pairs of
protons.
ROESY
(Rotating Frame Overhauser
Enhancement Spectroscopy)
Advanced form of NOESY ideal for large molecules.
COSY
(Correlated Spectroscopy)
A 2D experiment that yields a display of all coupled protons. The
diagonal and the projection on each axis are the one-dimensional
spectrum. The off-diagonal peaks indicate the presence of
coupling between pairs of protons.
COLOC
(Correlated Spectroscopy for Long-Range Couplings)
Experiment correlating the 13C spectrum on one axis and 1H
spectrum on the other. Cross peaks indicate long-range C-Hconnectivity.
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SECSY
(Spin Echo Spectroscopy)
Technique that yields the same information as the COSY
procedure, but with a different display format.
EXTASY
(Exchange Inter action Spectroscopy)
Useful procedure for determining sites that undergo chemical
exchange.
J-Resolved 2D NMR
A 2D technique that results in the normal spectrum projected on
one axis and coupling projected on to the other axis.
HETCOR
(Heteronuclear
Shift Cor relation)
Experiment correlates the 13C spectrum on one axis and 1H
spectrum on the other. Cross peaks indicate C-H connectivity.
HMBC
(Heteronuclear
Multiple Bond Correlation)
Advanced inverse detected experiment correlating the 13C
spectrum on one axis and 1H spectrum on the other. Cross peaks
indicate long-range C-H connectivity.
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HMQC
(Heteronuclear
Multiple Quantum Coherence)
Advanced inverse detected version of HETCOR. Experiment
correlates the 13C spectrum on one axis and 1H spectrum on the
other. Cross peaks indicate C-H connectivity.
HOHAHA
(Homonuclear
Hartmann Hahn)
Experiment that takes COSY a step further by correlating protons
with small coupling constants as occurs with long range coupling.Identifies spin sets, similar to TOCSY.
INADEQUATE
(Incredible Natural Abundance Double Quantum
Transfer Experiment)
Procedure used to directly obtain carbon-carbon connectivities
and, ultimately, the carbon skeleton of a molecule.
INSIPID
(Inadequate Sensitivity Improvement by Proton Indirect
Detection)
A reverse detection INADEQUATE experiment that greatly reduces
the aquisition
time.
TOCSY
(Total Correlation Spectroscopy)
Experiment that takes COSY a step further by correlating protons with small coupling constants as occurs with long range coupling.Identifies spin sets, similar to HOHAHA.
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STRUCTURE ELUCIDATION
1H-NMR.
Information about protons.
Integration shows number of protons.
Splitting shows how many protons onadjacent carbons, and chemical shift
shows shielding.
H3C
CH
H3C
CH2
OH
0.92, d
0.92, d 3.39, d
2.59, s (variable)1.77, m
(9 peakes)
0.92, d
1.77, m
2.59, s
(variable)
3.39, d
Decoupled 13C-spectrum.
No splitting. Chemical shift for
identification. Integration not valid
unless data collected under specialconditions.
H3C
CH
H3C
CH2
OH18.80
18.80
30.80
69.60 ISOBUTANOL
Integration
18.8030.8069.60
77.0(CDCl3
)
Solvent (CDCl3
). 77.0 ppm.Identified by chemical shift
and splitting. Deuterium has
spin quantum number 1 (3
spin states). Splits carbon to
three equal peaks.
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ATP. Attached Proton Test.Used to determine the number of
protons attached to each carbon.
Carbons with an even number of
protons (C and CH2
) go one direction.Carbons with an odd number of
protons (CH and CH3
) go the other. In
this spectrum, even protons go up and
odd protons go down.
DEPT 45. Distortionless
Enhancement
by Polarization Transfer.
This experiment with a 45 degree
decoupler
pulse gives a spectrum where
all carbons with attached protons areobserved. Quaternary carbons (with no
protons) are not observed. The
experiment is used in conjunction with
the DEPT 90 and DEPT 135
experiments to identify number ofprotons attached to each carbon.
18.80CH3
30.80
CH
69.60
CH277.0
(CDCl3
)
This peak is up so it is for
a carbon with an even
number (0) of proton. 18.80
30.80
69.60
These peaks are for carbons with
attached protons.
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DEPT 135.This experiment with a 135 degree
decoupler
pulse gives a spectrum
where CH and CH3
carbons are up, CH2carbons are down, quaternary carbons
are not observed. The experiment isused in conjunction with the DEPT 45
and DEPT 90 experiments to identify
number of protons attached to each
carbon.
DEPT 90.This experiment with a 90 degree
decoupler
pulse gives a spectrum
where CH carbons are observed. C,
CH2
and CH3
carbons are not
observed. The experiment is used in
conjunction with the DEPT 45 and
DEPT 135 experiments to identify
number of protons attached to each
carbon.
69.60
CH2
. A small peak is observed, but it is
much smaller in this spectrum. Shows that
this carbon is not a CH. Since it is
observed in the DEPT 45 it is also not a
quaternary carbon. The DEPT 135
distinguishes between remaining choices.
30.80CH3
. A small peak is observed, but it is
much smaller in this spectrum. Shows
that this carbon is not a CH. Since it is
observed in the DEPT 45 it is also not a
quaternary carbon. The DEPT 135
distinguishes between remaining choices.
CH. This peak is
observed at about
the same intensity
as in the DEPT
45, this show
s
that it is a CH
carbon.
18.80
18.80
30.80
69.60
CH2
. This peak is down
so it is a CH2
carbon.
CH. Since this peak is up it must be a CH3
or
CH, since it was present in the DEPT 90, it isa CH carbon.
CH3
. This peak is up, but is not observed in
the DEPT 90 so it must be a CH3
carbon.
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COSY. Correlation Spectroscopy.
This experiment shows proton-proton
correlation (which protons are coupled
to which). Coupled protons are typically
on adjacent carbons.
HETCOR. Heteronuclear
Correlation
Spectroscopy.
This experiment shows how protons
and carbons are coupled. Since
carbons are most strongly coupled toattached protons, this experiment
shows which protons are attached to
which carbons. This is useful for
assigning peaks in one spectrum if it isidentified in the other.
CH2
CH cross peaks.
This peak shows that
the CH2
protons are
coupled to the CH
proton.
3.39 1.77
0.92
CH3
CH cross peaks. This peak
shows that the CH3
protons are
coupled to the CH proton.
0.92
1.773.39
69.60
30.80
18.80
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PAMOIC ACID
CH2
OH
O
OH
OH
OH
O
12
345
6
7 8 9
10
HH
H
H
H
7.9, d
J = 7.9 Hz
7.2, t
J = 7.9 Hz
7.4, t
J = 7.9 Hz
8.1, d
J = 7.9 Hz 4.8, br s
8.5, s
1'2'
3'4'5'6'
7'8'
9'
10'
11
12
12'
Integration*
8.5, s
1H-NMR.
* Integration is not helpful since the molecule has two
similar ring systems, all the protons have an integration of 2.
Proton 1. No splitting. Integration 2. Identified by chemical shift (ring
proton) and splitting (only other proton with no splitting is the CH2
).
8.1,
d
Proton 5. 8.5 ppm
shift. No splitting. Integration 2. Identified as a ring proton by chemical shift. Doublet splitting is
consistent with Proton 5 or 8. NOE experiment is required to distinguish between position 5 and 8 (See NOESY data).
Proton 8. 7.9 ppm
shift. Doublet. Integration 2. Identified as a ring proton by chemical shift. Doublet splitting is
consistent with Proton 8 or 5. NOE experiment is required to distinguish between position 8 and 5 (See NOESY data).
7.9,
d
Proton 6. 7.4 ppm
shift. Triplet. Integration 2. Identified as a ring proton by chemical shift. Triplet splitting is consistent
with Proton 6 or 7. NOE experiment is required to distinguish between position 6 and 7 (See NOESY data for
experimental results identifying this proton.
7.4, t
Proton 7. 7.2 ppm
shift. Triplet. Integration 2. Identified as a ring proton by chemical shift. Triplet splitting is consistent
with Proton 6 or 7. NOE experiment is required to distinguish between position 6 and 7 (See NOESY data).
7.2, t
CH2
protons. 4.8 ppm
shift. No splitting. Integration 2. Identified by chemical shift (not a ring proton) and splitting
(only other proton with no splitting is on the ring).
4.8, br
s
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Decoupled carbon spectrum.
CH2
OH
O
OH
OH
OH
O
12
3456
7 8 9
10
173.0
114.6
131.9
153.8
121.0136.6123.8
123.72
129.3
1'2'3'
4'
9'10'
5'6'
7'8'
130.6127.2
20.4
173.0 ppm. Carboxylic acid carbon. Based on chemical shift. Not observed in DEPT-45spectrum so consistent with quaternary carbon.
153.8 ppm. Carbon 3. Not observed in DEPT-45 spectrum so must be quaternary carbon.
Chemical Shift is consistent with an aromatic carbon with -OH attached.
136.6 ppm. Carbon 10. Not observed in DEPT-45 spectrum so must be quaternarycarbon. Assignment is consistent with predicted chemical shift. Chemical shift is not
conclusive (difficult to distinguish between C-9 and C-10). Verified assignment would
require additional experiments (COLOC to show coupling to CH2
proton would be useful).
131.9 ppm. Carbon #1. Observed in all DEPT spectra so must be a CH carbon. Hetcor
shows coupling to proton #1.
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130.6 ppm. Carbon #8. Observed in all DEPT spectra so must be a CH carbon. Hetcor
shows coupling to proton #8.129.3 ppm. Carbon #6. Observed in all DEPT spectra so must be a CH carbon. Hetcor
shows coupling to proton #6.127.2 ppm. Carbon 9. Not observed in DEPT-45 spectrum so must be quaternary carbon.
Assignment is consistent with predicted chemical shift. Chemical shift is not conclusive
(difficult to distinguish between C-9 and C-10.) Verified assignment would require
additional experiments (COLOC to show coupling to adjacent carbons would be useful, but
complicated by aromatic ring.)
123.8 ppm. Two peaks are resolved. Peak at 123.80 is Carbon # 5. Peak at 123.72 is
Carbon #7. Both are observed in all DEPT spectra so must be a CH
carbon. Both are
identified from coupling in Hetcor.
121.0 ppm. Carbon #4. Not observed in DEPT-45 spectrum so must be quaternary carbon.
Assignment is consistent with predicted chemical shift. Chemical shift is not conclusive
(difficult to distinguish between C-4 and C-2.) Verified assignment would require additional
experiments (COLOC to show coupling to CH2
proton would be useful).
114.6 ppm. Carbon #2. Not observed in DEPT-45 spectrum so must be quaternary carbon. Assignment is consistent with chemical shift for aromatic carbon
with carboxylic acid.
Chemical shift is not conclusive (difficult to distinguish between C-4 and C-2.) Verified
assignment would require additional experiments (COLOC to show coupling to proton #1
would be useful).
20.4 ppm. CH2
Carbon. Only C-
with chemical shift in this region. Observed in DEPT-45,
Not observed in DEPT-90, and inverted phase in DEPT-135 so must be a CH2 carbon.
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DEPT 45. Distortionless
Enhancement
by Polarization Transfer.This experiment with a 45 degree
decoupler
pulse gives a spectrum where
all carbons with attached protons are
observed. Quaternary carbons (with noprotons) are not observed. The
experiment is used in conjunction with the
DEPT 90 and DEPT 135 experiments to
identify number of protons attached to
each carbon.
131.9 ppm. Carbon #1. Observed in all
DEPT spectra so must be a CH carbon.
Hetcor
shows coupling to proton #1.
130.6 ppm. Carbon #8. Observed in allDEPT spectra so must be a CH carbon.
Hetcor
shows coupling to proton #8.
129.3 ppm. Carbon #6. Observed in all
DEPT spectra so must be a CH carbon.Hetcor
shows coupling to proton #6.
129.3 ppm. Carbon #6. Observed in all
DEPT spectra so must be a CH carbon.
Hetcor
shows coupling to proton #6.
123.8 ppm. Two peaks are resolved.
Peak at 123.80 is Carbon # 5. Peak at
123.72 is Carbon #7. Both are observed
in all DEPT spectra so must be a CH
carbon. Both are identified from coupling
in Hetcor.
20.4 ppm. CH2
Carbon. Only carbon with
chemical shift in this region. Observed in
DEPT-45, Not observed in DEPT-90, andinverted phase in DEPT-135 so must be
a CH2 carbon.
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DEPT 90.
This experiment with a 90 degree decoupler pulse gives a spectrum where CH carbons
are observed. C, CH2
and CH3
carbons are
not observed. The experiment is used in
conjunction with the DEPT 45 and DEPT135 experiments to identify number of
protons attached to each carbon.
131.9 ppm. Carbon #1. Observed in all
DEPT spectra so must be a CH carbon.
Hetcor
shows coupling to proton #1.
130.6 ppm. Carbon #8. Observed in all
DEPT spectra so must be a CH carbon.
Hetcor
shows coupling to proton #8.
129.3 ppm. Carbon #6. Observed in all
DEPT spectra so must be a CH carbon.
Hetcor
shows coupling to proton #6.
123.8 ppm. Two peaks are resolved.
Peak at 123.80 is Carbon # 5. Peak at
123.72 is Carbon #7. Both are observed
in all DEPT spectra so must be a CHcarbon. Both are identified from coupling
in Hetcor.
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HETCOR. Heteronuclear
Correlation
Spectroscopy.
This experiment shows how protons and
carbons are coupled. Since carbons are
most strongly coupled to attached protons,
this experiment shows which protons areattached to which carbons. This is useful
for assigning peaks in one spectrum if it is
identified in the other.
(See this region
expanded
on next slide)
4.81 ppm
H-11 (CH2
), 20.4 ppm
C-11. H-11 peak is identified as CH2
by chemical shift.
C-11 is identified as CH2 by DEPT experiment.
8.50 ppm
H-1, 131.9 ppm
C-13. H-1
peak is a singlet, the only other singlet is
identified as CH2
, so must be H at
position 1. C-13 is identified bycorrelation to proton in position 1 in
HETCOR. In addition, DEPT experiment
identifies this carbon as having a single
proton which correlates with correct
assignment.
8.14 ppm
H-1, 123.72 ppm
C-13. H-1
peak is identified by splitting (doublet) as
position 5 or 8, NOESY correlation to
CH2
protons at 4.8 ppm
identifies thispeak (8.14 ppm) as position 5. C-13 is
identified by correlation to proton at
position 5 in HETCOR (further expansion
of HETCOR spectrum clearly
distinguishes between C-13 peaks at123.7 and 123.8 ppm). In addition, DEPT
experiments identify this carbon is
attached to one proton. Consistent with
assignment.
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7.9 ppm
H-1, 130.6 ppm
C-13. H-1 peak
is identified by splitting (doublet) as
position 5 or 8, NOESY correlation to
position 1 at 8.5 ppm
identifies this peak(7.9 ppm) as position 8. C-13 is identified
by correlation to proton at position 8 in
HETCOR. In addition, DEPT experiments
identify this carbon is attached to one
proton. Consistent with assignment.
7.24 ppm
H-1, 123.81 ppm
C-13.
H-1
peak is identified by splitting (triplet) as
position 6 or 7; selective homonuclear
decoupling at 7.9 ppm
causes this peakto collapse to a doublet; since peak at 7.9
is assigned position 8 by NOESY, this
peak (7.24 ppm) is identified as position
7. C-13 is identified by correlation to
proton at position 8 in HETCOR (furtherexpansion of HETCOR spectrum clearly
distinguishes between C-13 peaks at
123.7 and 123.8 ppm). In addition, DEPT
experiments identify this carbon is
attached to one proton. Consistent withassignment.
7.4 ppm
H-1, 129.3 ppm
C-13. H-1 peak is
identified by splitting (triplet) as position 6 or 7;
Selective Homonuclear
decoupling at 8.1 ppm
causes this peak to collapse to a doublet,since peak at 8.1 is assigned as position 5 byNOESY, this peak (7.4 ppm) is identified asposition 6 (Same information would be
available from a COSY spectrum). C-13 is
identified by correlation to proton at position 6
in HETCOR. In addition, DEPT experiments
identify this carbon is attached to one proton.Consistent with assignment.
(Expanded region)
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COSY Spectrum.
C. This COSY Cross peak shows the coupling between peaks at 7.2 and 7.4 ppm. This
is consistent with the coupling between the two triplets for protons 6 and 7.
A. This COSY Cross peak shows the coupling between peaks at 8.1 and 7.4 ppm. This
shows the connection between protons 5 and 6 OR between 7 and 8.
It is not possible to
distinguish which pair from the COSY spectrum.
B. This COSY Cross peak shows the coupling between peaks at 7.2 and 7.9 ppm. This
shows the connection between protons 5 and 6 OR between 7 and 8.
It is not possible to
distinguish which pair from the cosy
spectrum.
A B
C
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NOESY Spectrum.
A. This NOE cross peak shows the NOE between peaks at 8.5 and 7.9
ppm. Since the
peak at 8.5 is a singlet and has a chemical shift consistent with a ring proton, it has been
assigned proton 1. This peak does not appear in the COSY spectrum, so it must be
caused by NOE. The NOE peak identifies the peak at 7.9 as proton
8.
A
B CD
E
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SYRINGALDEHYDE
H3CO
CO
H
H3CO
HO1
3
5
1'
2'
3'
Pale yellowish needles
Melting point: 113-114o
Boiling point: 192-193o
UV λmax
nm (logε) (MeOH):
303 (4.01), 229.8 (4.15),
225.8 (4.14), 214.8 (4.20),
198.4 (3.92) nm 200 nm 250 300 350 400 450
IRν
max
(CHCl3
):3282 (OH),
2923, 2850.5
(C-H, aldehyde),
1671 (C=O, ald.),
1606-1462 (C=C,Ar),1330 (overt. aldehyde
C-H, bend.),
1252, 1207 (C-O-C),
1141, 1109 (C-O)831, 727 cm-1
4000 3500 3000 2500 2000 1500 1000 500
Wavenumber
cm-1
T r a n s m i t t a n c e [ % ]
IR Spectrum
UV spectrum
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182
40 60 80 100 120 140 160 180
166
153
139
123
m/z
183
51.9
11193.1
78
65.1
10
20
30
40
50
60
70
80
90
0
%age
EI-MS
HR-MS
EI-MS m/z (rel. int. %):
182 [M]+
(100), 153 [M-HCO]
+
(10.2),
123 [M –
(MeO
+ CO]+
(6.7)
HR-MS:
The molecular formula was
deduced as C9
H10
O4
through HR-MS,
showing a [M]+
ion peak at m/z
182.04329, (Calcd. for 182.04192), and
indicating 5 degrees of unsaturation.
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1H-NMR.The 1H-NMR spectrum displayed a
singlet at δ 9.80, which is characteristic
for an aldehyde
group while a two-
proton singlet at δ 7.13 revealed the
presence of a symmetrically substituted
aromatic ring. Similarly, a six-proton
singlet at δ 3.89 was assignable to
two
magnetically equivalent methoxyl
groups in the molecule.
1H-NMR
(CDCl3
) (300 MHz) (δ
ppm):
9.80 (1H, s, H-1'), 7.13 (2H, s, H-2, H-6), 3.89 (6H, s, OMe-2', OMe-3')
H3CO
C
O
H
H3CO
HO1
3
5
1'
2'
3'
H
H
9.80 s
7.13 s
7.13 s
3.89 s
3.89 s
9.80, s
7.13, s
3.89, s
Note:
Some extra peaks show that purity is
not good. It may be mixture of two isomers.
0.010.0 1.02.03.04.05.06.07.08.09.0
ppm
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