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Organic Organic Chemistry Chemistry

William H. Brown &William H. Brown &

Christopher S. FooteChristopher S. Foote

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Nuclear Nuclear Magnetic Magnetic

ResonanceResonanceChapter 13Chapter 13

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Molecular SpectroscopyMolecular Spectroscopy Nuclear magnetic resonance (NMR) Nuclear magnetic resonance (NMR)

spectroscopyspectroscopy:: a spectroscopic technique that gives us information about the number and types of atoms in a molecule, for example, about the number and types of • hydrogen atoms using 1H-NMR spectroscopy• carbon atoms using 13C-NMR spectroscopy• phosphorus atoms using 31P-NMR spectroscopy

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Nuclear Spin StatesNuclear Spin States An electron has a spin quantum number of 1/2

with allowed values of +1/2 and -1/2 • this spinning charge creates an associated

magnetic field• in effect, an electron behaves as if it is a tiny bar

magnet and has what is called a magnetic moment

Pauli exclusion principle:Pauli exclusion principle: two electrons can occupy the same atomic or molecular orbital only if they have paired (opposite) spins

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Nuclear Spin StatesNuclear Spin States Any atomic nucleus that has an odd mass, an

odd atomic number, or both also has a spin and a resulting nuclear magnetic moment

The allowed nuclear spin states are determined by the spin quantum number, I , of the nucleus

A nucleus with spin quantum number II has 22II + 1 + 1 spin states. If I = 1/2, there are two allowed spin states

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Nuclear Spin StatesNuclear Spin States Spin quantum numbers and allowed nuclear

spin states for selected isotopes of elements common to organic compounds

1H 2H 12C 13C 14N 16O 31P 32SElement

Nuclear spinquantum number (I )

Number ofspin states

1/2 1 0 0 01/2 1

2 3 1 2 3 1

1/2

2 1

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Nuclear Spins in BNuclear Spins in B00 Within a collection of 1H and 13C atoms,

nuclear spins are completely random in orientation

When placed in a strong external magnetic field of strength B0, however, interaction between nuclear spins and the applied magnetic field is quantized, with the result that only certain orientations of nuclear magnetic moments are allowed

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Nuclear Spins in BNuclear Spins in B00 For 1H and 13C, only two orientations are

allowed.

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Nuclear Spins in BNuclear Spins in B00 In an applied field strength of 7.05T, which is

readily available with present-day superconducting electromagnets, the difference in energy between nuclear spin states for • 1H is approximately 0.120 J (0.0286 cal)/mol, which

corresponds to electromagnetic radiation of 300 MHz (300,000,000 Hz)

• 13C is approximately 0.030 J (0.00715 cal)/mol, which corresponds to electromagnetic radiation of 75MHz (75,000,000 Hz)

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Nuclear Spin in BNuclear Spin in B00 The energy difference between allowed spin

states increases linearly with applied field strength. • values shown here are for 1H nuclei.

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance When nuclei with a spin quantum number of

1/2 are placed in an applied field, a small majority of nuclear spins are aligned with the applied field in the lower energy state

The nucleus begins to precess and traces out a cone-shaped surface, in much the same way a spinning top or gyroscope traces out a cone-shaped surface as it precesses in the earth’s gravitational field

We express the rate of precession as a frequency in hertz

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance If the precessing nucleus is irradiated with

electromagnetic radiation of the same frequency as the rate of precession,• the two frequencies couple, • energy is absorbed, and • the nuclear spin is flipped from spin state +1/2 (with

the applied field) to -1/2 (against the applied field)

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance Coupling of precession frequency and the

frequency of electromagnetic radiation

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance ResonanceResonance:: the absorption of electromagnetic

radiation by a precessing nucleus and the flip of its nuclear spin from a lower energy state to a higher energy state

The instrument used to detect this coupling of precession frequency and electromagnetic radiation records it as a signal

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance If we were dealing with 1H nuclei isolated from

all other atoms and electrons, any combination of applied field and radiation that produces a signal for one 1H would produce a signal for all 1H. The same is true of 13C nuclei

But hydrogens in organic molecules are not isolated from all other atoms; they are surrounded by electrons, which are caused to circulate by the presence of the applied field

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance The circulation of electrons around a nucleus

in an applied field is called diamagneticdiamagnetic currentcurrent and the nuclear shielding resulting from it is called diamagnetic shieldingdiamagnetic shielding

The difference in resonance frequencies among the various hydrogen nuclei within a molecule due to shielding/deshielding is generally very small

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance The difference in resonance frequencies for

hydrogens in CH3Cl compared to CH3F under an applied field of 7.05T is only 360 Hz, which is 1.2 parts per million (ppm) compared with the irradiating frequency

360 Hz300 x 106 Hz

1.2 = 1.2 ppm106

=

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance It is customary to measure the resonance

frequency (signal) of individual nuclei relative to the resonance frequency (signal) of a reference compound

The reference compound now universally accepted is tetramethylsilane (TMS)

Tetramethylsilane (TMS)

CH3

Si CH3

CH3

H3C

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Nuclear Magnetic ResonanceNuclear Magnetic Resonance For a 1H-NMR spectrum, signals are reported

by their shift from the 12 H signal in TMS For a 13C-NMR spectrum, signals are reported

by their shift from the 4 C signal in TMS Chemical shift (Chemical shift ():): the shift in ppm of an NMR

signal from the signal of TMS

=Shift in frequency from TMS (Hz)Frequency of spectrometer (Hz)

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NMR spectrometerNMR spectrometer

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NMR SpectrometerNMR Spectrometer Essentials of an NMR spectrometer are a

powerful magnet, a radio-frequency generator, and a radio-frequency detector

The sample is dissolved in a solvent, most commonly CDCl3 or D2O, and placed in a sample tube which is then suspended in the magnetic field and set spinning

Using a Fourier transform NMR (FT-NMR) spectrometer, a spectrum can be recorded in about 2 seconds

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NMR SpectrumNMR Spectrum 1H-NMR spectrum of methyl acetate

• Downfield:Downfield: the shift of an NMR signal to the left on the chart paper

• Upfield:Upfield: the shift of an NMR signal to the right on the chart paper

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Equivalent HydrogensEquivalent Hydrogens Equivalent hydrogens:Equivalent hydrogens: have the same

chemical environment• a molecule with 1 set of equivalent hydrogens gives

1 NMR signal

H3C

C C

CH3

H3C CH3

CH3CCH3 ClCH2CH2Cl

Propanone(Acetone)

1,2-Dichloro-ethane

Cyclopentane 2,3-Dimethyl-2-butene

O

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Equivalent HydrogensEquivalent Hydrogens• a molecule with 2 or more sets of equivalent

hydrogens gives a different NMR signal for each set

1,1-Dichloro-ethane

(2 signals)

(Z)-1-Chloro-propene

(3 signals)

Cl

C

H

C

H

CH3Cl

CH3CHCl O

Cyclopent-anone

(2 signals)

Cyclohexene (3 signals)

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Signal AreasSignal Areas Relative areas of signals are proportional to

the number of H giving rise to each signal Modern NMR spectrometers electronically

integrate and record the relative area of each signal

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Chemical Shift - Chemical Shift - 11H-NMRH-NMRType of Hydrogen

0 (by definition)

Type of Hydrogen

Chemical Shift ()

1.6-2.6

2.0-3.0

0.8-1.0

1.2-1.4

1.4-1.7

2.1-2.3

0.5-6.0

2.2-2.6

3.4-4.0

Chemical (Shift )

3.3-4.0

2.2-2.5

2.3-2.8

0.5-5.0

RC CHO

O

RCH2 OR

(CH3 )4Si

ArCH3

RCH3

RCCH3

ROH

RCH2 OH

ArCH2 R

RCH2 R

R3 CH R2 NH

RCCH2R

R2 C=CRCHR2

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Chemical Shift - Chemical Shift - 11H-NMRH-NMRType of Hydrogen

Type of Hydrogen

Chemical Shift ()

4.6-5.0

9.5-10.1

5.0-5.7

10-13

3.7-3.9

4.1-4.7

3.1-3.3

3.4-3.6

3.6-3.8

4.4-4.5

6.5-8.5

Chemical (Shift )

O

O

O

O

R2 C=CHR

RCH

RCOH

RCH2 Cl

RCH2 Br

RCH2 I

RCH2 F

ArH

R2 C=CH2RCOCH3

RCOCH2R

4.5-4.7ArOH

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Chemical ShiftChemical Shift Depends on (1) electronegativity of nearby atoms, (2)

the hybridization of adjacent atoms, and (3) diamagnetic effects from adjacent pi bonds• electronegativity

Electroneg-ativity of X

Chemical Shift () of Methyl Hydrogens

4.0

3.53.1

2.82.5

2.11.8

4.26

3.473.05

2.682.16

0.860.00 ( )by definition

CH3OH

CH3F

CH3Cl

CH3Br

CH3I

(CH3 )4C(CH3 )4Si

CH3-X

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Chemical ShiftChemical Shift• hybridization of adjacent atoms

RCH3, R2CH2, R3CH

R2C=CHR, R2C=CH2

RCHO

R2C=C(R)CHR2

RC CH

Allylic

Type of Hydrogen(R = alkyl)

Name ofHydrogen

Chemical Shift ()

Alkyl

Acetylenic

Vinylic

Aldehydic

0.8 - 1.7

1.6 - 2.6

4.6 - 5.7

9.5-10.1

2.0 - 3.0

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Chemical ShiftChemical Shift Magnetic induction in pi bonds of a

• a carbon-carbon triple bond shields an acetylenic hydrogen and shifts its signal upfield (to the right) to a smaller value

• a carbon-carbon double bond deshields vinylic hydrogens and shifts their signal downfield (to the left) to a larger value

RCH3

Type of H Name alkyl

R2 C=CH2 vinylicRC CH acetylenic

0.8- 1.0

4.6 - 5.72.0 - 3.0

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Chemical ShiftChemical Shift• magnetic induction in the pi bonds of carbon-

carbon triple bond (Fig 13.7)

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Chemical ShiftChemical Shift• magnetic induction in the pi bond of a carbon-

carbon double bond (Fig 13.8)

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Chemical ShiftChemical Shift• magnetic induction of the pi electrons in an

aromatic ring (Fig. 13.9)

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Signal Splitting (n + 1)Signal Splitting (n + 1) Peak:Peak: the units into which an NMR signal is

split; doublet, triplet, quartet, etc. Signal splitting:Signal splitting: splitting of an NMR signal into

a set of peaks by the influence of neighboring nonequivalent hydrogens

(n + 1) rule:(n + 1) rule: the 1H-NMR signal of a hydrogen or set of equivalent hydrogens is split into (n + 1) peaks by a nonequivalent set of n equivalent neighboring hydrogens

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Signal Splitting (n + 1)Signal Splitting (n + 1)• 1H-NMR spectrum of 1,1-dichloroethane

For this hydrogen, n = 3; its signal is split into (3 + 1) or 4 peaks - a quartet

For these hydrogens, n = 1; their signal is split into (1 + 1) or 2 peaks - a doublet

CH3-CH-Cl

Cl

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Signal Splitting (n + 1)Signal Splitting (n + 1)ProblemProblem: predict the number of 1H-NMR signals and the splitting pattern of each

CH3CCH2 CH3 CH3CH2 CCH2CH3

CH3CCH(CH3)2

(a) (b)

(c)

O O

O

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Origin of Signal SplittingOrigin of Signal Splitting When the chemical shift of one nucleus is

influenced by the spin of another, the two are said to be coupled

Consider nonequivalent hydrogens Ha and Hb on adjacent carbons• the chemical shift of Ha is influenced by whether

the spin of Hb is aligned with or against the applied field

C C

Ha Hb

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Origin of Signal SplittingOrigin of Signal Splitting

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Origin of Signal SplittingOrigin of Signal Splitting The signal of Ha is split into two peaks of equal

area (a doublet) by its nonequivalent neighbor Hb.

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Signal SplittingSignal Splitting Pascal’s Triangle. As

illustrated by the highlighted entries, each entry is the sum of the values immediately above it to the left and the right.

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Structure

Ha

1 3 3 1

1 2 1

1 1

Spin States of Hb Signal of Ha

C C Hb

HbHa

C C

Ha Hb

Hb

Hb

C C

HbHa

C C

Ha

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Coupling ConstantsCoupling Constants Coupling constant (J):Coupling constant (J): the distance between peaks in

a split signal, expressed in hertz• the value is a quantitative measure of the magnetic

interaction of nuclei whose spins are coupled

8-11 Hz

8-14 Hz 0-5 Hz 0-5 Hz6-8 Hz

11-18 Hz 5-10 Hz 0-5 Hz

CCHa

C C

HbHaC

Hb

C

Ha

Hb

Ha

Hb

Ha

Hb HbHa

Hb

Ha

C CHaHb

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Coupling ConstantsCoupling Constants Jab for a doublet and a triplet from splitting of

Ha by nonequivalent hydrogen(s) Hb.

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Coupling ConstantsCoupling Constants• 1H-NMR spectrum of 3-pentanone; scale expansion

shows the triplet quartet pattern more clearly

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Stereochem & TopicityStereochem & Topicity Depending on the symmetry of a molecule,

otherwise equivalent hydrogens may be• homotopic• enantiotopic• diastereotopic

The simplest way to visualize topicity is to substitute an atom or group by an isotope. Is the resulting compound• the same as its mirror image• different from its mirror image• are diastereomers possible

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Stereochem & TopicityStereochem & Topicity Homotopic atoms or groups

• homotopic atoms or groups have identical chemical shifts under all conditions

Achiral

H

C

H

Cl

Cl

H

C

D

Cl

Cl

Dichloro-methane(achiral)

Substitution does not produce a stereocenter;therefore hydrogensare homotopic.

Substitute one H by D

Achiral

H

C

H

Cl

Cl

H

C

D

Cl

Cl

Dichloro-methane(achiral)

Substitution does not produce a stereocenter;therefore hydrogensare homotopic.

Substitute one H by D

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Stereochem & TopicityStereochem & Topicity Enantiotopic groups

• enantiotopic atoms or groups have identical chemical shifts in achiral environments

• they have different chemical shifts in achiral environments

Chiral

H

C

H

Cl

F

H

C

D

Cl

F

Chlorofluoro-methane(achiral)

Substitute one H by D

Substitution produces a stereocenter;therefore, hydrogens are enantiotopic. Both hydrogens are prochiral; one is pro-R-chiral, the other is pro-S-chiral.

Chiral

H

C

H

Cl

F

H

C

D

Cl

F

Chlorofluoro-methane(achiral)

Substitute one H by D

Substitution produces a stereocenter;therefore, hydrogens are enantiotopic. Both hydrogens are prochiral; one is pro-R-chiral, the other is pro-S-chiral.

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Stereochem & TopicityStereochem & Topicity Diastereotopic groups

• H atoms on C-3 of 2-butanol are diastereotopic• substitution by deuterium creates a stereocenter• because there is already a stereocenter in the

molecule, diastereomers are now possible

• diastereotopic hydrogens have different chemical shifts under all conditions

H OH

HH

H OH

HD

Chiral

Substitute one H on CH2 by D

2-Butanol(chiral)

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Stereochem & TopicityStereochem & Topicity The methyl groups on carbon 3 of 3-methyl-2-

butanol are diastereotopic• if a methyl hydrogen of carbon 4 is substituted by

deuterium, a new stereocenter is created• because there is already one stereocenter,

diastereomers are now possible

• protons of the methyl groups on carbon 3 have different chemical shifts

OH

3-Methyl-2-butanol

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Stereochem and TopicityStereochem and Topicity 1H-NMR spectrum of 3-methyl-2-butanol

• the methyl groups on carbon 3 are diastereotopic and appear as two doublets

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1313C-NMR SpectroscopyC-NMR Spectroscopy Each nonequivalent 13C gives a different signal

• a 13C signal is split by the 1H bonded to it according to the (n + 1) rule

• coupling constants of 100-250 Hz are common, which means that there is often significant overlap between signals, and splitting patterns can be very difficult to determine

The most common mode of operation of a 13C-NMR spectrometer is a hydrogen-decoupled mode

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1313C-NMR SpectroscopyC-NMR Spectroscopy In a hydrogen-decoupled mode, a sample is

irradiated with two different radio frequencies• one to excite all 13C nuclei• a second broad spectrum of frequencies to cause

all hydrogens in the molecule to undergo rapid transitions between their nuclear spin states

On the time scale of a 13C-NMR spectrum, each hydrogen is in an average or effectively constant nuclear spin state, with the result that 1H-13C spin-spin interactions are not observed; they are decoupled

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1313C-NMR SpectroscopyC-NMR Spectroscopy• hydrogen decoupled 13C-NMR spectrum

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Chemical Shift - Chemical Shift - 1313C-NMRC-NMR

0-40

110-160

165 - 180

160 - 180

165 - 185

180 - 215

40-80

40-80

35-80

25-65

65-85

100-150

20-60

15-55

10-40

Type of Carbon

ChemicalShift ()

Chemical (Shift )

Type ofCarbon

RC CR O

O

O

O

C RRCH3

RCH2 R

R3 CH

R2 C=CR2

RCNR2

R3 COR

RCH, RCR

RCOH

RCOR

RCH2 Cl

RCH2 Br

RCH2 I

R3 COH

O

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The DEPT MethodThe DEPT Method In the hydrogen-decoupled mode, information

on spin-spin coupling between 13C and attached hydrogens is lost

The DEPT method is an instrumental mode that provides a way to acquire this information• Distortionless Enhancement by Polarization Distortionless Enhancement by Polarization

TransferTransfer (DEPTDEPT) is an NMR technique for distinguishing among 13C signals for CH3, CH2, CH, and quaternary carbons

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The DEPT MethodThe DEPT Method The DEPT methods uses a complex series of

pulses in both the 1H and 13C ranges, with the result that CH3, CH2, and CH signals exhibit different phases;• signals for CH3 and CH carbons are recorded as

positive signals

• signals for CH2 carbons are recorded as negative signals

• quaternary carbons give no signal in the DEPT method

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Isopentyl acetateIsopentyl acetate• (a) proton decoupled and (b) DEPT

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Interpreting NMR SpectraInterpreting NMR Spectra AlkanesAlkanes

• 1H-NMR signals appear in the range of 0.8-1.7 • 13C-NMR signals appear in the considerably wider

range of 10-60

AlkenesAlkenes • 1H-NMR signals appear in the range 4.6-5.7• 1H-NMR coupling constants are generally larger for

trans vinylic hydrogens (J= 11-18 Hz) compared with cis vinylic hydrogens (J= 5-10 Hz)

• 13C-NMR signals for sp2 hybridized carbons appear in the range 100-160, which is downfield from the signals of sp3 hybridized carbons

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Interpreting NMR SpectraInterpreting NMR Spectra• 1H-NMR spectrum of vinyl acetate (Fig 13.18)

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Interpreting NMR SpectraInterpreting NMR Spectra• graphical analysis of signal splitting of the three

vinylic hydrogens in vinyl acetate (Fig 13.19)

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Interpreting NMR SpectraInterpreting NMR Spectra AlcoholsAlcohols 1H-NMR O-H chemical shifts often appears in

the range 3.0-4.0, but may be as low as 0.5. • 1H-NMR chemical shifts of hydrogens on the carbon

bearing the -OH group are deshielded by the electron-withdrawing inductive effect of the oxygen and appear in the range 3.0-4.0

EthersEthers • a distinctive feature in the 1H-MNR spectra of ethers

is the chemical shift, 3.3-4.0, of hydrogens on carbon attached to the ether oxygen

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Interpreting NMR SpectraInterpreting NMR Spectra• 1H-NMR spectrum of 1-propanol (Fig. 13.20)

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Interpreting NMR SpectraInterpreting NMR Spectra Aldehydes and ketonesAldehydes and ketones

• 1H-NMR: aldehyde hydrogens appear at 9.5-10.1• 1H-NMR: -hydrogens of aldehydes and ketones

appear at 2.2-2.6• 13C-NMR: carbonyl carbons appear at 180-215

Carboxylic acidsCarboxylic acids• 1H-NMR: carboxyl hydrogens appear at 10-13,

lower than most any other hydrogens • 13C-NMR: carboxyl carbons appear at 160-180

AminesAmines• 1H-NMR: amine hydrogens appear at 0.5-5.0

depending on conditions

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Index of H DeficiencyIndex of H Deficiency Index of hydrogen deficiency (IHD):Index of hydrogen deficiency (IHD): the sum of

the number of rings and pi bonds in a molecule

To determine IHD, compare the number of hydrogens in an unknown compound with the number in a reference hydrocarbon of the same number of carbons and with no rings or pi bonds• the molecular formula of the reference hydrocarbon

is CnH2n+2

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Index of H DeficiencyIndex of H Deficiency

• for each atom of a Group 7 element (F, Cl, Br, I), add one H

• no correction is necessary for the addition of atoms of Group 6 elements (O,S) to the reference hydrocarbon

• for each atom of a Group 5 element (N, P), subtract one hydrogen

IDH =2

(Hreference - Hmolecule)

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Index of H DeficiencyIndex of H DeficiencyProblem:Problem: isopentyl acetate has a molecular formula of C7H14O2. Calculate its IHD• reference hydrocarbon C7H16

• IHD = (16-14)/2 = 1

Problem:Problem: calculate the IHD for niacin, molecular formula C6H6N2O• reference hydrocarbon C6H16

• IHD = (16 - 6)/2 = 5

O

O

Isopentyl acetate

N

NH2

O

Niacin

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Prob 13.13Prob 13.13 Calculate the index of hydrogen deficiency of each

compound.

(a)

(b)

(d)

(c)

(e)

(f)

Aspirin, C9H8 O4

Ascorbic acid (vitamin C), C6H8 O6

Pyridine, C5H5N

Urea, CH4N2O

Cholesterol, C27 H46 O

Dopamine, C8H11NO2

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Prob 13.16Prob 13.16 Assign each constitutional isomers its spectrum.

(a)

(c)

(b) Spectrum 1Spectrum 2Spectrum 374.6630.54

7.73 29.21

43.7470.97 62.93

32.79

31.86

22.6325.7529.1426.60

23.2714.09

14.08

OH

CH3

OH

CH2CH3

CH3CCH2 CH2CH2CH3

CH3CH2 CH2CH2CH2CH2CH2 OH

CH3CH2 CCH2CH3

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Prob 13.17Prob 13.17 Assign each compound its 13C spectrum.

(a)

(b)

(c)

23.0115.97 26.54

20.85

30.6731.35 34.20

31.30

23.56 32.88

35.1444.60

Spectrum 3Spectrum 2Spectrum 1

CH3

CH3

CH3

CH3

CH3

CH3

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Prob 13.23Prob 13.23 Compound K, molecular formula C6H14O, readily

undergoes acid-catalyzed dehydration when warmed with phosphoric acid to give compound L, molecular formula C6H12, as the major organic product.

The 1H-NMR spectrum of compound K shows signals at 0.90 (t, 6H), 1.12 (s, 3H), 1.38 (s, 1H), and 1.48 (q, 4H). The 13C-NMR spectrum of compound K shows signals at 72.98, 33.72, 25.85, and 8.16.

Deduce the structural formulas of compounds K and L.

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Prob 13.28Prob 13.28 Assign each carbon in each compound its correct 13C

chemical shift.Br

13C DEPT

51.5543.22

26.4621.0013.40

CH

CH2

CH2

CH3

CH3CH2CH2CHCH3

CH3

(a) (b)

13C

147.70108.33

30.56

22.4712.23

CH2

CH2

CH3CH3

CH3CH2C=CH2

CH3

-----

DEPT

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Prob 13.28 (cont’d)Prob 13.28 (cont’d) Assign each carbon in each compound its correct 13C

chemical shift.

CH2=CHCH2CHCH3

CH3

13C

137.81115.26

43.35

28.1222.26

CH2

CH

CH2

CHCH3

(c)

DEPT

(d)

13C DEPT

49.0233.1528.72

CH2

CH3

CH3CCH2Br

CH3

CH3

-----

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Prob 13.28 (cont’d)Prob 13.28 (cont’d) Assign each carbon in each compound its correct 13C

chemical shift.

CH3CH2CCH2CH3

O

13C

207.835.17.5 CH3

-----

(e)

CH2

CH3CH2CCH3

O

13C

208.737.630.1 CH3

-----

(f)

CH2

9.2 CH3

DEPT DEPT

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Prob 13.28 (cont’d)Prob 13.28 (cont’d) Assign each carbon in each compound its correct 13C

chemical shift.

(h)

13C DEPT

171.1763.12

37.2125.0524.45

CH2

CH2

CH3CH3

CH3COCH2CH2CHCH3

21.02

----

CH

(g)

13C DEPT

177.4851.50

33.9419.01

CH

CH3

CH3

CH3CHCOCH3

-----

CH3

CH3O O

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NuclearNuclear

Magnetic Magnetic ResonanceResonance

End Chapter 13End Chapter 13