Chapter 18 Carboxylic Acids Chapter 18 Carboxylic Acids and Their Derivatives.and Their Derivatives.Nucleophilic AdditionNucleophilic Addition--

Elimination at the Acyl CarbonElimination at the Acyl Carbon羧酸及其衍生物

酰基碳原子上的亲核加成－消除反应

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Chapter 18

18.1 Introduction

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Chapter 18

R C LO

L = OH, X, R,COO

OR', NH2

The carboxyl group is one of the most widely occurring functional in chemistry and biochemistry. Not only are carboxylic acids themselves important, but the carboxyl group is the parent group of a large family of related compounds called acyl compounds or carboxylic acid derivatives.

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Chapter 18

RC

X

O

RCO

RC

NH2

OR C

RC

O

O

RCO

R'O

RC

Cl

O

N

Acyl halide(Acid halide)

Acyl chloride Acid anhydride

EsterNitrile

RC

NHR'

O

RC

NR'R"

O

Amide

酰卤 酰氯 酸酐

酯腈

酰胺

RC

OH

O

Carboxylic acid

羧酸

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Chapter 18

18.2 Nomenclature and Physical Properties

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Chapter 18

18.2A Carboxylic AcidsCarboxylic acids that are derived from openchainalkanes are systematically named by replacing the terminal –e of the corresponding alkane name with –oic acid.The carboxyl carbon atom is assigned number 1

4-Methylpentanoic acid

CH3CHCH2CH2CO

OHCH3

4-甲基戊酸

3-Ethyl-6-methyloctanedioic acid

CCH2CHCH2CH2CHCH2CO

OHCH3O

HOCH2CH3

3-甲基-6-乙基辛二酸

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Compounds that have a —COOH group bonded to a ring are named using the suffix –carboxylic acid. The carboxylic acid carbon is attached to C1 and is not itself numbered in this system.CCS system:烃名＋羧酸——脂肪酸烃名＋甲酸——芳香酸

COOH

Br

12

34

5

6

COOH1

2

34

5CO2H

3-Bromocycloheanecarboxylic acid

1-Cyclopentenecarboxylic acidBenzenecarboxylic acid

(Benzoic acid)

苯甲酸

3-溴环己烷羧酸

1-环戊烯羧酸

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Chapter 18

Some Common Names of Carboxylic Acids

苯甲酸

丙烯酸

硬脂酸

棕榈酸，软脂酸

月桂酸

酪酸

醋酸

蚁酸

Stearic acidCH3(CH2)16COOH

Lauric acidCH3(CH2)10COOH

Benzoic acidC6H5COOHAcrylic acidCH2=CHCOOH

Palmitic acidCH3(CH2)14COOH

Butyric acidCH3CH2CH2COOHAcetic acidCH3COOHFormic acidHCOOH

Common nameStructure

Many carboxylic acids have common names that are derived from Latin or Greek words that indicate one of their natural sources.

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Chapter 18

18.2B Carboxylic SaltsSalts of carboxylic acids are named as –ates; in both common and systemic names.

-ic acid→ -ate

CH3CO2K CO2NaPotassium acetate Sodium benzoate乙酸钾 苯甲酸钠

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18.2C Acidity of Carboxylic AcidsMost unsubstituted carboxylic acids pKa =4~5

RCO2H

MgO

NaOH

Na2CO3

NaHCO3

RCO2Na + CO2 + H2O

(RCO2)2Mg + H2O

RCO2Na + H2O

RCO2Na + CO2 + H2O

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Chapter 18

Carboxylic acids having electron-withdrawing groups are stronger than unsubstituted acids.Carboxylic acids having electron-donating groups are weaker than unsubstituted acids.

C O

O

C O

O

Electron-withdrawing groups

Electron-donating groups

C

O

R

H

O

CO

RO

CO

RO

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Chapter 18

Acidity of Some Carboxylic Acids

Strongeracid

Weakeracid4.76CH3COOH

4.31PhCH2COOH3.83HOCH2COOH2.89BrCH2COOH2.86ClCH2COOH2.59FCH2COOH1.48Cl2CHCOOH0.70Cl3CCOOH0.23F3CCOOHpKaStructure

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Chapter 18

Acidity of Chlorosubstituted Butanoic Acid

4.87CH3CH2CH2COOH

4.50ClCH2CH2CH2COOH

4.05CH3CHClCH2COOH

2.85CH3CH2CHClCOOH

pKaStructure

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Chapter 18

Acidity of Some Substituted Benzoic Acids

3.423.492.21—NO2

3.55—CN3.973.832.92—Cl3.973.812.85—Br4.023.852.86—I4.204.204.20—H4.384.273.91—CH3

4.474.094.09—OCH3

4.574.082.98—OH

pmoY

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Chapter 18

18.2D Dicarboxylic Acids3-Ethyl-6-methyloctanedioic acid

CCH2CHCH2CH2CHCH2CO

OHCH3O

HOCH2CH3

3-甲基-6-乙基辛二酸

酞酸

富马酸

马来酸

肥酸

琥珀酸

缩苹果酸

草酸

Adipic acidHOOC(CH2)4COOH

Malonic acidHOOCCH2COOH

Phthalic acido-C6H4(COOH)2

Fumaric acidHOOCCH=CHCOOH(trans)Maleic acidHOOCCH=CHCOOH(cis)

Succinic acidHOOC(CH2)2COOH

Oxalic acidHOOCCOOHCommon nameStructure

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Chapter 18

18.2E EstersSystematic names for esters are derived by first giving the name of the alkyl group attached to oxygen and then identifying the carboxylic acid. In so doing, the –ic acid ending is replaced by –ate.

R C OR'R C OHO O

Replaced H by R'

CH3CO

OCH2CH3

COCH3

O

COCH2CH3

O

Ethyl acetate Methyl benzoate Ethyl cyclohexanecarboxylate乙酸乙酯 苯甲酸甲酯 环己烷羧酸乙酯

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18.2F Carboxylic AnhydridesSymmetrical anhydrides of straight-chainmonocarboxylic acids, and cyclic anhydrides ofdicarboxylic acids, are named by replacing the word acid with anhydrideWhen the acyl groups are different, they are cited in alphabetical order.

CH3CO

O C CH3

O

HCO

O C CH3

OO

O

O

乙酸酐 丁二酸酐 甲(酸)乙(酸)酐

Acetic anhydride Butanedioic anhydride Acetic formic anhydride(Succinic anhydride)

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18.2G Acyl Chlorides-ic acid → -yl halide or-carboxylic acid → carbonyl halide酰基名 + 卤素名

CH3CClO C

Br

O

CCl

O

乙酰氯 苯甲酰溴 环己烷羧酰氯

Acetyl chloride Benzoyl bromide Cyclohexanecarbonylchloride

Ethanoyl chloride

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Chapter 18

18.2H AmidesAmides with an unsubstituted –NH2 group are named by replacing the –oic acid or –ic acidending with –amide or by replacing the –carboxylic acid ending with –carboxamide.Alkyl groups on the nitrogen of amides are named as substituents, and the named substituent is prefaced by N- or N,N-.

CH3CO

NH2

CNH2

O

HCO

N(CH3)2

乙酰胺 环戊烷羧酰胺 N,N-二甲基甲酰胺Acetamide Cyclopentanecarboxamide N,N-Dimethylformamide

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Chapter 18

18.2I NitrilesCompounds containing the –CN functional group are known as nitriles. Simple acyclicnitriles are named by adding –nitrile as a suffix to the alkane names, with the nitrile carbon itself numbered C1.More complex nitriles are named as derivatives of carboxylic acid by replacing the –ic acid or –oic acid ending with –onitrile, or by replacing the carboxylic acid ending with –carbonitrile.

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Chapter 18

Alkanenitrile-ic acid or –oic acid→-onitrile-carboxylic acid→-carbonitrile×腈(含CN碳原子)

CH3CN CN

CN

乙腈

CH3CH3

2,2-Dimethylcyclohexancarbonitrile

CH2 CH CNEthanenitrile(acetonitrile)

Propenenitrlie(acrylonitrile) Benzonitrile

2,2-二甲基环己烷甲腈

丙烯腈 苯甲腈

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Chapter 18

18.2J Spectroscopic Properties of Acyl Compounds

IR:O—H, 2500 ~ 3100 cm-1

N—H, 3140 ~ 3500 cm-1

C=OCarboxylic acids 1700 ~ 1725Acid anhydrides 1800 ~ 1850 and 1740 ~ 1790Acyl chloride 1780 ~ 1850Esters 1735~1750Amides 1630 ~ 1690

C≡N 2250

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Chapter 18

CH2 CO

OHδ 10 ~ 12δ 2.0 ~ 2.5

1H NMR

13C NMR

R CO

L

δ 160 ~ 180

L = OH, X, OCOR, OR', NH2

C NR

δ 115 ~ 120

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Chapter 18

18.3 Preparation of Carboxylic Acids

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Chapter 18

1. By oxidation of alkenes and alkynes

RCH CHR'KMnO4

OH

H3O∆

RCO2H R'CO2H+RC CR'

RCH CHR'(1) O3

(2) H2O2RCO2H R'CO2H+

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2. By oxidation of aldehydes and primary alcohols

RCHO

RCH2OH

RCO2H

(1) AgO or Ag(NH3)2 + OH-(2) H3O+

(1) KMnO4, OH-, heat

(2) H3O+

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Chapter 18

3. By oxidation of alkylbenzenes

CH3KMnO4

OH

H3O∆ CO2H

4. By oxidation of methyl ketones

Ar C CH3

O (1) X2 / NaOH

(2) H3OAr C OH

O+ CHX3

Haloform reaction

KMnO4

OH

H3O∆

HO2C(CH2)4CO2H

O

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Chapter 18

5. By hydrolysis of cyanohydrins and other nitriles

R C R'O

+ HCN R CR'

OHCN

Cyanohydrin

HA

H2OR C

R'

OHCO2H

α−Hydroxy acid

R X + NaCN R CNHA

H2OR CO2H

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Chapter 18

6. By hydrolysis of carboxylic acid derivatives

RC

X

O

RCO

RC

O

O

RC

NH2

OR

CO

R'O

H2O

H+ or OH-R CO2H

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Chapter 18

7. By carbonation of Grignard reagents

RMgX + CO2 RCO2MgXH2O

H+RCO2H

Et2ORMgX + CO2 RCO2MgX

H2O

H+RCO2H

Et2O

CH3CH2CH2CH2ClMgEt2O CH3CH2CH2CH2MgCl

CO2 H2O

H+CH3CH2CH2CH2CO2H

CH3CH3

CH3

BrMgEt2O

CO2 H2O

H+

CH3CH3

CH3

CO2H