20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of...

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C A 20 RETANOIC ACID

Transcript of 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of...

Page 1: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

Carboxylic Acids20

RETANOIC ACID

Page 2: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.1 CARBOXYLIC ACIDS AND ACYL GROUPS

C O

O

carboxyl group

H R C O

O

carboxylic acids

H Ar C O

O

H

methanoic acid

H C O

O

1

H H C O

O

2

H H C O

O

H

3

C

O

H OH

134 pm

120 pm

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Figure 20.1 Bonding in Carboxylic Acids

!e π bond is formed by overlap of the 2p orbitals of carbon and oxygen.

(a) Lowest energy bonding orbital in methanoic acid (formic acid)

(b) Electron distribution in methanoic acid

Regions colored red have a partial negative charge (at the carboxyl oxygens) and regions colored blue have a partial positive charge (at the hydroxyl hydrogen and carbonyl carbon).

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20.1 CARBOXYLIC ACIDS AND ACYL GROUPSThe Acyl Group and Carboxylic Acid Derivatives

R C O

O

examples of esters (acyl groups shown in red)

R' R C O

O

Ar Ar C O

O

Ar'

R C NH2

O

primary amide

R C NHR

O

R C NR2

O

secondary amide tertiary amide

R C Cl

O

acid chloride

R C O

O

R C S

O

acid anhydride thioester

C R

O

R

lactone(a cyclic ester)

O

O

N O

H lactam(a cyclic amide)

N

SN

H

CO2H

CH3

CH3

C

O

O

penicillin G

H

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20.2 NOMENCLATURE OF CARBOXYLIC ACIDSCommon Names of Carboxylic Acids

γ-bromo-β-ethylcaproic acid

CH3 CH2 CH CCH

Br

CH2 OH

O

αβγδε

CH2CH3

α-bromoglutaric acid

CH2 CH2 CH C

Br

αβγ

β-methyladipic acid

C CH2 CHαβγδ

HO

O

CH2

CH3

CH2 C OH

O

OH

O

CHO

O

OH

CO2H

CO2H

CO2H

CO2H

HO2C

salicylic acid phthalic acid terephthalic acid

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Table 20.1Nomenclature of Carboxylic AcidsFormula Common Name IUPAC NameHCO2H formic acid methanoic acidCH3CO2H acetic acid ethanoic acidCH3CH2CO2H propionic acid propanoic acidCH3(CH2)2CO2H butyric acid butanoic acidCH3(CH2)3CO2H valeric acid pentanoic acidCH3(CH2)4CO2H caproic acid hexanoic acidCH3(CH2)6CO2H caprylic acid octanoic acidCH3(CH2)10CO2H lauric acid dodecanoic acidCH3(CH2)12CO2H myristic tetradecanoic acidCH3(CH2)14CO2H palmitic hexadecanoic acidCH3(CH2)16CO2H stearic octadecanoic acid

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20.2 NOMENCLATURE OF CARBOXYLIC ACIDSIUPAC Names of Carboxylic Acids

4-bromo-3-methylpentanoic acid

CH3 CH CCH

Br

CH2 OH

O

2345

CH3

1

4--methyl-2-pentynoic acid

CCH C OH

O

2345

CH3

1CCH3

1. Name the longest continuous carbon chain containing the carboxyl carbon atom as the parent chain. Replace the !nal -e of the parent hydrocarbon by the ending -oic acid. Table 20.1 gives examples of IUPAC names of unsubstituted carboxylic acids.

Number the parent chain by assigning the number 1 to the carboxyl carbon atom. Do not add the number “1” to the name to indicate the position of the carboxyl carbon because it must be located at the end of the chain. Add the names and locations of any substituents as pre!xes to the parent name.

2.

"e carboxylic acid group has a higher priority than double or triple bonds. To name a carboxylic acid that contains a double or triple bond, replace the !nal -e of the name of the parent alkene or alkyne name with the su#x -oic acid. Indicate the position of the multiple bond with a pre!x.

3.

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20.2 NOMENCLATURE OF CARBOXYLIC ACIDSIUPAC Names of Carboxylic Acids

3-hydroxy-2-methylbutanoic acid

CH3 CH CCH

OH

OH

O

234

CH3

1

2-methyl-3-oxobutanoic acid

CH3 C CCH

O

OH

O

234

CH3

1

O

CO2H

Cl

CO2H

3-oxocyclopentanecarboxylic acid cis-2-chlorocyclohexanecarboxylic acid

!e carboxylic acid functional group has a higher priority than aldehyde, ketone, halogen, hydroxyl, and alkoxy groups. Indicate the names and locations of these groups with pre"xes to the name of the parent carboxylic acid.

4.

If a carboxylic acid contains an aldehyde or ketone, the names of the carbonyl group is -oxo. !e priority order is aldehyde > ketone.

5.

Name compounds that have a —COOH group bonded to a cycloalkane ring as derivatives of the cycloalkane with the su$x carboxylic acid. !e ring atom to which the carboxyl group is attached is C-1. Do not include this number in the name.

6.

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Name dicarboxylic acids by adding the su!x dioic acid to the name the parent alkane that contains both carboxylic acid groups. Number the chain starting with the carboxyl carbon closest to the "rst substituent.

7.

CH2 3 4

CH2CH3

5C OH

O

1CH2 CH2CHO

O

2-ethylpentanedioic acid

2345C OH

O

1CH2 CH2CHO

O

3-chlorohexanedioic acid

CH

Cl

CH2

6

20.2 NOMENCLATURE OF CARBOXYLIC ACIDSIUPAC Names of Carboxylic Acids

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20.1 CARBOXYLIC ACIDS AND ACYL GROUPSNames of Carboxylate Anions

CH3 C O

O

sodium ethanoate (sodium acetate)

Na CH2 CH2 C O

O

K

potassium 3-phenylpropanoate(potassium β-phenylpropionate)

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20.3 PHYSICAL PROPERTIES OF CARBOXYLIC ACIDSBoiling Points

CH3 C O

O

bp 118 oC

H CH3 C CH3

O

bp 56.5 oC bp -7 oC

CH3 C CH3

CH2

C

O H O

C

OHO

CH3 CH3

hydrogen-bonded dimer of acetic acid

Table 20.2Boiling Points of Carboxylic AcidsIUPAC Name Common Name Boiling Point, oCmethanoic acid formic acid 101ethanoic acid acetic acid 118propanoic acid propionic acid 141butanoic acid butyric acid 1642-methylpropanoic acid isobutyric acid 155 pentanoic acid valeric acid 1863-methylbutanoic acid isovaleric acid 1772,2-dimethylpropanoic acid pivalic acid 164hexanoic acid caproic acid 205octanoic acid caprylic acid 239decanoic acid capric 270dodecanoic acid lauric acid 299

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20.3 PHYSICAL PROPERTIES OF CARBOXYLIC ACIDSMelting Points

Table 20.2Melting Points of Carboxylic AcidsNumber of Carbon Atoms

IUPAC Name Common Name Melting Point, oC

10 decanoic acid capric acid 31.312 dodecanoic acid lauric acid 43.214 tetradecanoic acid myristic acid 54.416 hexadecanoic acid myristic acid 62.818 octadecanoic acid isobutyric acid 69.9 20 eicosanoic acid arachidic acid 75.422 docosanoic acid behenic acid 79.924 tetracosanoic acid lignoceric acid 84.226 hexacosanoic acid ceratoic acid 87.7

C OH

O

CH2 CH2CHO

O

succinic acid mp 185 oC

C OH

O

CH2CHO

O

malonic acid mp 136 oC

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20.3 PHYSICAL PROPERTIES OF CARBOXYLIC ACIDSSolubilities

C

O

OH3CH

H

OH

OH

HHO

H

hydrogen bonds between acetic acid and water in aqueous solution

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20.4 ACIDITY OF CARBOXYLIC ACIDSResonance Stabilization of the Carboxylate Ion

CH3CH2OH + H2O CH3CH2O + H3O Ka = 1 x 10-16

CH3CO2H + H2O CH3CO2 + H3O Ka = 1.8 x 10-5

CH3 C O

O

1

CH3 C O

O

2Resonance structures of acetate ion

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20.4 ACIDITY OF CARBOXYLIC ACIDSInductive Effect on Acidity

C

O

OCl H

HHδδ

δ

δ

Electron density is pulled towards the oxygen atom.

Electron density is pulled towards the carbon atom.

The chlorine atom pulls electron density to itself.

CH3CH2CHCO2H

Cl

CH3CHCH2CO2H

Cl

CH2CH2CH2CO2H

Cl

pKa 2.84 pKa 4.06 pKa 4.52

CH3CH2CH2CO2H

pKa 4.72

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Table 20.4pKa Values of Carboxylic AcidsIUPAC Name Formula pKa

methanoic acid HCO2H 3.75ethanoic acid CH3CO2H 4.72propanoic acid CH3CH2CO2H 4.87butanoic acid CH3(CH2)2CO2H 4.822-methylbutanoic acid (CH3)2CHCO2H 4.84pentanoic acid CH3(CH2)3CO2H 4.812,2-dimethylmethylpropanoic acid (CH3)CCO2H 5.03

#uoroethanoic acid FCH2CO2H 2.59chloroethanoic acid ClCH2CO2H 2.86bromoethanoic acid BrCH2CO2H 2.90idoethanoic acid ICH2CO2H 3.18dichloroethanoic acid Cl2CHCO2H 1.24trichloroethanoic acid Cl3CCO2H 0.64tri#uoroethanoic acid F3CCO2H 0.23

methoxyethanoic acid CH3OCH2CO2H 3.55cyanoethanoic acid CNCH2CO2H 2.46nitroethanoic acid NO2CH2CO2H 1.72

Table 20.5pKa Values of Dicarboxylic AcidsIUPAC Name Formula pKa1 pKa2

oxalic acid HO2CCO2H 1.27 4.27malonic acid HO2CCH2CO2H 2.85 5.70succinic acid HO2C(CH2)2CO2H 4.35 5.64glutaric acid HO2C(CH2)3CO2H 4.41 5.41adipic acid HO2C(CH2)4CO2H 4.42 5.42pimelic acid HO2C(CH2)5CO2H 4.51 5.42suberic acid HO2C(CH2)6CO2H 4.52 5.41azelic acid HO2C(CH2)7CO2H 4.54 5.41sebacic acid HO2C(CH2)8CO2H 4.55 5.40

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20.4 ACIDITY OF CARBOXYLIC ACIDSAcidity of Aromatic Carboxylic Acids

Table 20.6pKa Values of SubstitutedBenzoic AcidsSubstituent Ortho Meta ParaCH3O 4.06 4.10 4.47CH3 3.91 4.27 4.37H 4.20 4.20 4.20Cl 2.92 3.82 3.98NO2 2.17 3.49 3.42

C O

O

1

C O

O

2Resonance structures of benzoate ion

CO2H CO2H CO2H

NO2 OCH3

pKa = 4.20 pKa = 3.42 pKa = 4.47

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20.6 SYNTHESIS OF CARBOXYLIC ACIDSOxidative Methods

KMnO4

CO2H

tetralin phthalic acidCO2H

C CH2

CH3

CH3

C CH3

OI2

OH-C CH2

CH3

CH3

C OH

O

CH3(CH2)8CH2OHCrO3

H2SO4CH3(CH2)8CO2H

1-decanol decanoic acid

CHOCrO3

H2SO4

CO2H

3-cyclohexenecarbaldehyde 3-cyclohexenecarboxylic acid

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20.6 SYNTHESIS OF CARBOXYLIC ACIDSCarboxylation of Grignard Reagents

R MgBr + C

O

O

R C O

O

MgBrH3O+

R C OH

O

R X3. H3O+ R C OH

O1.Mg

etherR MgX

2. CO2

3. H3O+

1.Mg /ether2. CO2

Br

CH3

C

CH3

O

OH

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20.6 SYNTHESIS OF CARBOXYLIC ACIDSHydrolysis of Nitriles

R XH3O+

R C OH

O

+ C N R C N

2. H3O+1.KCN

CH2Br CH2CO2H

Page 21: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.7 REDUCTION OF CARBOXYLIC ACIDSReduction with Lithium Aluminum Hydride

C O

O

HRLiAlH4 C O

O

R Li+ + H2 + AlH3

C O

O

R Li+ + H AlH3 C O

O

R

H

AlH2

Li+

C O

O

R

H

AlH2

Li+ C H

O

R Li++ H AlH2O-

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20.7 REDUCTION OF CARBOXYLIC ACIDSReduction with Diborane

BH3

THFCH2OHCCH3CH2

O

CCH3CH2

O

C OH

O

BH3

THFCH2CH2 C OH

O

O2N CH2CH2 CH2OHO2N

Page 23: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.8 DECARBOXYLATION REACTIONS

R C O

O

H R H + CO2

HCH2CHO

O

HCH2CCH3

O

OHCCH2

O

CHO

O

OHCCH2

O

CCH3

O

heat

heat

malonic acid

acetoacetic acid

O C O

O C O

+

+

O

C C

OH

CH3 OHH

O

CCCH3

H

H

+CO2

H

C

O

CH3 C

H

H

Hslow fast

CO2H

CO2H

heatH

CO2H

+ CO2

1,1-cyclobutanedicarboxylic acid cyclobutanecarboxylic acid

C CH2CO2H

Oheat

C CH3

O

+ CO2

3-phenyl-3-oxopropanoic acid 1-phenyl-ethanone

O

C C

OH

HO OHH

O

CCHO

H

H

+

H

C

O

HO C

H

H

Hslow fastC

O

O

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20.8 DECARBOXYLATION REACTIONSThe Hunsdiecker Reaction

CH2CH2CH2 C O

O

Ag CH2CH2CH2 BrBr2

Page 25: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.8 DECARBOXYLATION REACTIONSBiochemical Decarboxylation Reactions

CO2-

C H

C

C

CO2-H

HH

CO2-

+ NAD+

CO2-

C O

C

C

HH

HH

CO2-

+ NADH + CO2

HO

isocitrate α-ketoglutarate

isocitrate dehydrogenase

Mg2+

C C

C

O2CCH2

H

O

O

O

CO2

-CO2 C CO2CCH2

H O

CO2H+

CO2-

C O

C

C

HH

HH

CO2-

α-ketoglutarate(S)-3-oxalosuccinate

C

O

CRC

O

OH H

Mg2+

C

O

CR

H

H

Mg+

+ C

O

O

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20.9 REACTIONS OF CARBOXYLIC ACIDS AND THEIR DERIVATIVES: A PREVIEWNucleophilic Acyl Substitution

C

O

R'R

1. Nu

2. H3O+C

OH

NuR'

R

tetrahedral product

C

O

LRC

O

LNu

R

tetrahedral intermediate

Nu C

O

NuR

R C O

O

H Nu+

addition reaction acid-base reaction

HNu

R C O

ONuR C O

O

H

Nu

Page 27: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.10 CONVERSION OF CARBOXYLIC ACIDS INTO ACYL HALIDES

COH

O

+ SOCl2

CCl

O

+ SO2 + HCl

RC

OH

O

+R

CO

O

+ HClCl

SCl

O

SCl

O

RC

O

O

SCl

O

ClR

CO

O

SCl

O

Cl

RC

O

O

SCl

O

Cl RC

O

Cl+

O

S

O

+ Cl-

Page 28: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.11 CONVERSION OF CARBOXYLIC ACIDS INTO ESTERSAlkylation of Carboxylate Anions

C O

O

CH3 I C O

O

CH3 + I-+

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20.11 CONVERSION OF CARBOXYLIC ACIDS INTO ESTERSEsterification With Diazomethane

R C O

O

R C O

O

CH3 + N2H C N

H

H

N+

R C O

O

H C N

H

H

N R C O

O

C N N

H

H

H+

R C O

O

C N N

H

H

H+ R C O

O

CH3 + N N

+

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20.11 CONVERSION OF CARBOXYLIC ACIDS INTO ESTERSReaction of Acyl Chlorides With Alcohols

RC

O

Cl+ +R'OH

RC

O

OR'pyridine

HCl

R C O

O

R'

ClR

C

O

Cl+ +

RC

O

OR' ClO R'H

H

+

H

RC

O

OR'

H

RC

O

OR' H+

1.

C

O

Cl

+ HOCH2OH more sterically hindered 2o alcohol

less sterically hindered 1o alcohol

C

O

OCH2

OH

Page 31: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.11 CONVERSION OF CARBOXYLIC ACIDS INTO ESTERSFischer Esterification

R C OH

O

CH3CH2 OH R C O

O

CH2CH3 + H2O+

Adding alcohol "pushes" the reaction to the right.

Removing water "pulls" the reaction to the right.

Page 32: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.12 MECHANISM OF ESTERIFICATION

C OH

O

+CH318O H C

O

18O CH3 + H2O

R C OH

O

+ H R C OH

O H

R C OH

O H

+

-H

R C OH

O H

R C OH

O HO R'H R C O

O

R'

OH H

H

R C O

O

R'

OH H

H

R C O

O

R'

OH

H

(hydrate of an ester)

-HR C O

O

R'

O

H

(conjugate acid of an ester)

R C O

O

R'

O

HH-H2O

R C O R'

OH H H

R C O R'

O H

R C O R'

O H

-HR C O R'

O

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20.13 BRIEF SYNTHETIC REVIEWFunctional Group Modifications in Organic Synthesis

O

CO2H

O

CH2OH

O

CO2H

O

CH2OHBH3

THF

O

CO2H

O

CO2CH31. CH3OH

H2SO4

2. HOCH2CH2OH

TsOH

CO2CH3

O O

3. LiAlH4

3a. H3O+

O

CH2OH

Page 34: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

Figure 20.2 Infrared Spectrum of Acetic Acid

20.14 SPECTROSCOPY OF CARBOXYLIC ACIDSInfrared Spectroscopy

Perc

ent

Tran

smit

tanc

e

50

100

4000 3000 2000 1000Wavenumber (cm–1)

1500 500

O—H stretch 1-butanolCH3(CH2)2CH2OH

3350 cm-1

C—O stretch CH3 C OH

O

acetic acidC=O stretch

O–H stretch

Page 35: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

Chemical shift, ppm (δ) 010 8 6 4 2

3 H triplet

TMS

2 H quartet

1 H

OCCH2

O

CH3 H

12

carboxylic acid proton

20.14 SPECTROSCOPY OF CARBOXYLIC ACIDSProton NMR Spectroscopy

Figure 20.3 Proton NMR Spectrum of Propanoic Acid

Page 36: 20 - Elsevier.com · 2014. 5. 6. · 20.2 NOMENCLATURE OF CARBOXYLIC ACIDS IUPAC Names of Carboxylic Acids 3-hydroxy-2-methylbutanoic acid CH3 CH CH C OH OH O 4 3 2 CH3 1 2-methyl-3-oxobutanoic

20.14 SPECTROSCOPY OF CARBOXYLIC ACIDSProton NMR Spectroscopy

Figure 20.4 C-13 NMR Spectrum of Propanoic Acid

Chemical shift, ppm (δ)

TMS

CH2

OCCH2

O

CH3 H

carbonyl carbon CH3

020406080100120140160180

181.5

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