organic chemistry laboratory ii example ir and nmr 1 16 ir and nmr ana
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Organic Chemistry Laboratory II
EXAMPLE IR AND NMR (#1)
16-IR and NMR Analysis
100
WAVEHUMBER CM*
630 425
4000
3000
2300
2000
1300 1309
1100 1000
900
800
700
90
70
60
30
40
30
20
10
о
2.5
3
ก
S
NEAT
Pappas and Goicoechea-Pappas
20
10
11
12
13
Aldrich Chemical Company
14
15
16
WAVELENGTH IN MICRONS
100
16-8
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IR and NMR ANALYSIS
CHM 2211L
16-IR and NMR Analysis
MODULE 16
NAME Example 1
YOU MUST SUPPORT YOUR REASONING BY FILLING IN ALL BLANKS
Major Functional Group Analysis
carboxylic acid, amide (primary or secondary), aldehyde, ester, ketone, alcohol, phenol,
amine (primary or secondary), terminal alkyne, or nitrile.
O
||
(6) Major Functional Group Present:
- C-OR (ester)
Reasoning using IR spectrum:
Give specific location of absorption(s)
Reasoning using NMR spectrum:
Only RCOOH and RCHO need justification.
Minor Functional Group Analysis
@ 1754 cm¯ and C-O @ 1198 cm
Indicate the presence or absence of each of the following minor functional groups, by
placing an A for Absent, P for Present, or M for Maybe in the space provide. You must
include your justification.
(6) Aromatic Group
Presence
IR Peak(s) indicating
Presence or Absence
= C-H @ 3021 cm- (due to alkene)
Absent
no
1575-1625 cm-
(157
1475 1525 cm-
If aromatic, type of substitution (mono, ortho, meta, para):
Reasoning:
(4) Alkene Group
Presence
Present
IR Peak(s) indicating
Presence or Absence
= C H @ 3021 cm¯
C=C @ 1666 cm-
Pappas and Goicoechea-Pappas
NMR Peak(s) indicating
Presence or Absence
no peaks in NMR
between 6.0 - 9.5 ppm
NMR Peak(s) indicating
Presence or Absence
peak @ 4.6 ppm
16-9
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Н R₁
H
16- IR and NMR Analysis
Ro" or RCC or RC-CH
C=C
Η
H
'R
_ R R
If alkene, type of substitution:
H
H
R
H
R
H
C=C
C=C
H´
H
H
H
H
H
R
R'
R
R
900 cm¯
R
963 cm-
Η
H
Reasoning:
C= C 833 cm-
-->{-- >{\|--><
IR Peak(s) indicating Presence or Absence
H
R
C=
R
R
Group
(3) Alkyl
(3) Ether
(3) Nitro
Presence
Present
Maybe
Absent
C H@2941 cm-
I can't be confirmed due to presence of C-O from ester.
no N=O @ 15151560 cm & @ 1345 1385 cm-
NMR Analysis
(4) 1. How many different types of protons are there? 3
Reasoning: There are 3 different peaks (singlets)
(5) 2. Give the area (proton ratio) for each signal. (When the signal is split, consider the center
of the signal to denote its location)
1. Peak @
4.6
ppm ---> Area = 2
4. Peak @
ppm -> Area =
2. Peak @
2.1
ppm-
---> Area = 3
5. Peak @
ppm
---> Area =
3. Peak @ 1.9 ppm
---> Area = 3
6. Peak @
ppm ---> Area =
(6) 3. Taking all the above information into account, draw the structural formula for the
compound.
R
H
R
R
is eliminated because the NMR indicates that there are 2
alkene protons and this would only have one.
H
C'
Η
is eliminated because the alkene protons from this type of
R molecule would be split and no splitting is seen in NMR.
Since all 3 signals are singlets, we must come up with a structure in which
the C's have no adjacent H's.
Pappas and Goicoechea-Pappas
2.1 ppm
CH3-C.
бот
4.6 ppm
CH 3
1.9 ppm
16-10
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EXAMPLE IR AND NMR (#2)
16-IR and NMR Analysis
4000
3000
2300
2000
2000
1900
1300
1100
1000
900
WAVENUMBER CM
700
650 625.
30
10
DEAT
100
80
500
400
300
Pappas and Goicoechea-Pappas
°
Aldrich Chemical Company
12
13
100
90
10
16
14
15
WAVELENGTH IN MICRONS
16-11
Scanned with CamScanner Organic Chemistry Laboratory II
IR and NMR ANALYSIS
CHM 2211L
16-IR and NMR Analysis
MODULE 16
NAME Example 2
YOU MUST SUPPORT YOUR REASONING BY FILLING IN ALL BLANKS
Major Functional Group Analysis
carboxylic acid, amide (primary or secondary), aldehyde, ester, ketone, alcohol, phenol,
amine (primary or secondary), terminal alkyne, or nitrile.
(6) Major Functional Group Present:
-OH (phenol or aromatic alcohol)
Reasoning using IR spectrum:
Give specific location of absorption(s)
-OH @ 3448 cm (broad) and
=C-H @3040 cm and
benzene ring @ 1587 cm and 1492 cm
Reasoning using NMR spectrum:
Only RCOOH and RCHO need justification.
Minor Functional Group Analysis
Indicate the presence or absence of each of the following minor functional groups, by
placing an A for Absent, P for Present, or M for Maybe in the space provide. You must
include your justification.
(6) Aromatic Group
Presence
Present
IR Peak(s) indicating
Presence or Absence
= C H @ 3040 cm¯
1587 cm-
1492 cm-
NMR Peak(s) indicating
Presence or Absence
multiplet centered
@ 7 ppm
If aromatic, type of substitution (mono, ortho, meta, para): ortho or para
Reasoning: 749 cm
(ortho)
ог 837 cm
(para)
(4) Alkene Group
Presence
Absent
IR Peak(s) indicating
Presence or Absence
= C H @ 3040 cm
no C = C @ 1630-1680 cm-
NMR Peak(s) indicating
Presence or Absence
peak @ 4.7 is in alkene region,
but upon further examination
it is due to the -OH
Pappas and Goicoechea-Pappas
16-12
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