ByByDr. Nahed NasserDr. Nahed Nasser

Carboxylic Acids and Carboxylic Acids and Their DerivativesTheir Derivatives

CONTENTS

• Structure of carboxylic acids

• Nomenclature

• Physical properties of carboxylic acids

• Preparation of carboxylic acids

•Reaction os carboxylic acids

•Derivatives of carboxylic acids:

a. Acid chlorides

b. Esters

c. Amides

d. Anhydrides

•Occurrence and uses of carboxylic acids and their derivatives

CARBOXYLIC ACIDSCARBOXYLIC ACIDS

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STRUCTURE OF CARBOXYLIC ACIDSSTRUCTURE OF CARBOXYLIC ACIDS

• Carboxylic acids are organic acids contain one or more carboxyl group

•A carboxyl group is made up of a carbonyl (C=O) group and a hydroxyl (O-H) group

• It is often written in condensed form as –CO2H or –COOH

• The general formula of a carboxylic acid is R-COOH or Ar-COOH

NOMENCLATURE Of CARBOXYLIC ACIDSNOMENCLATURE Of CARBOXYLIC ACIDS

IUPAC Nomenclature of carboxylic acidsIUPAC Nomenclature of carboxylic acids

• Find the longest continuous carbon chain contains the COOH group to get the name of the parent hydrocarbon, the ending -e is replaced by the suffix –oic acid.• Number the chain starting with the carbon of COOH group as C-1• If there are substituents identify their names and positions and list them as prefixes in alphabetical order.

Examples: Examples: (CH(CH33))22CH - CH(CHCH - CH(CH33) - CH) - CH22 - CH - CH22 - COOH - COOH is called 4,5-Dimethylhexanoic acid

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COOH COOH

COOH COOH

NH2Cl

2-Isopropyl-cyclobutanecarboxylic acid

3-Amino-cyclohexanecarboxylic acid

Br

2-Bromo-4-chloro-cyclopentanecarboxylic acid

Cyclopropanecarboxylic acid CH(CH3)2

COOH

Benzene carboxylic acid

COOH COOH

Benzene-1,2-dicarboxylic acid

OH COOH

2-Hydroxybenzene carboxylic acid

• Cyclic compounds (Aliphatic or aromatic) containing one or more COOH groups attached to the ring are named by identifying the name of the ring followed by the word carboxylic acid or dicarboxylic acids etc. The carbon atom bearing the carboxylic group is numbered 1 and the substituents are numbered relative to it.

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Common nomenclature of carboxylic acidsCommon nomenclature of carboxylic acids

• Some carboxylic acids are called after characteristic properties or their origin.

Formula IUPAC name Common name origin of name

HCOOH methanoic acid formic acid Latin for ant

CH3COOH ethanoic acid acetic acid Latin for vinegar

CH3CH2COOH propanoic acid propionic acid Greek for milk

CH3 (CH2)2COOH butanoic acid butyric acid Latin for butter

CH3 (CH2)3COOH pentanoic aic valeric acid valerian root

• The positions of the carbons present on the acid chain, are located by the Greek letters α indicating the carbon atom next to COOH group (C2), β (C3), γ (C4), δ (C5), etc .

-C-C-C-C-C-COOH123456

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• Some aromatic acids have common names.

CH3

COOH

CH3

CH3

common: -- Dimethyl butyric acidIUPAC: 2,3-Dimethyl butanoic acid

COOH COOH COOH

OH COOH

COOH

COOH

Benzoic acid Salicylic acid Phthalic acid Terphathalic acid

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• Carboxylic acids are polar, they can form hydrogen bonds with water molecules

• Smaller carboxylic acids (1 to 4 carbons) are soluble with water• Whereas the solubility of bigger carboxylic acids decrease with size due to the increasing hydrophobic nature of the alkyl chain.

•Aromatic acids are insoluble in water

PHYSICAL PROPERTIES OF CARBOXYLIC ACIDS

SolubilitySolubility

R

C

O

O

H

O

H

H

H

O

H

H-Bonds

• Carboxylic acids have exceptionally high boiling points than alcohols of identical relative molecular masses, For example:

M.F. M.W bp / °C

1- Propanol C3H8O 60.01 97.2

Ethanoic acid C2H4O2 60.05 118

• This is due to carboxylic acids usually exist as dimeric pairs by forming two intramolecular hydrogen bonds in nonpolar media

Boiling PointsBoiling Points

H3C C

O

O H O

H O

C CH3

Hydrogen bond

Acidity and acid strength• Carboxylic acids are the most acidic simple organic compounds (they are

stronger acids by over ten powers of ten compared to alcohols of comparable weights); also they are more acidic than phenols

• However, they are weak acids compared to inorganic acids (HCl or H2SO4)

• Adjacent electron withdrawing substituents nearnear the carboxyl group increase the acidity

• Whereas electron releasing substituents decrease the acidity .

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• HCOOH > CH3COOH > CH3CH2COOH > CH3CH2CH2CH2COOH ( size of R group)

• Cl3CCOOH > Cl2CHCOOH > ClCH2COOH > CH3COOH > (OCH3)CH2COOH ( number of e.w.g. and e.r. g.)

• CH3CH2CH2CH(Cl)COOH > CH3CH2CH(Cl)CH2COOH > CH3CH(Cl)CH2CH2COOH > CH2(Cl)CH2CH2CH2COOH ( position of e.w.g. relative to COOH group)

•

COOH

NO2

COOH

NO2

COOH

O2N

COOH

CH3

COOH

> > > >

Preparation of Carboxylic acids1- Oxidation of primary alcohols or aldehydes

R CH2 OHH2Cr2O7 or K2Cr2O7/ H

+

or KMnO4 / heat

OR C

OHPrimary alcohol carboxylic acid

R CH OH2Cr2O7 or K2Cr2O7/ H

+

or KMnO4 / heat

OR C

OHcarboxylic acidAldehyde

2- Oxidation of AlkylbenzenesC H 3

KMnO 4

Toluene

COOH

Benzoic acid

CH 2 CH 3KMnO 4

COOH

Benzoic acid

+ + OH 2CO 2

3- Carbonation of Grignard Reagents

R MgX + C OO R

O

OMgX

R

O

OH

CH3 MgX + C OO CH3

O

OMgX

CH3

O

OH

4- Hydrolysis of nitriles

R C N RCOOH + NH4+H3O

+/ heat

R-XNaCN

Reactions of Carboxylic Acids

1- Salts Formation

RCOOH

KOH or NaOHRCOO

-K

+ or Na

+ + H2O

NaHCO3 RCOO-Na

+

+ CO2 H2O+

NH3 RCOO-NH4

+

COOH

OH

+

+

NaHCO3

NaHCO3

COO-Na

+

N . R

Sodium Benzoate

2- Substitution of hydroxyl group

RCOOH

R'OH / H+

NH3

SOCl2

1) PCl52) R''COO

-Na

+

RCOOR'

RCONH2

RCOCl

RCOOCOR"

Ester

Amide

Acid Chloride

Anhydride

Carboxylic Acid Derivatives

R C

O

Cl

R C

O

OR'

R C

O

N

R C

O

O C

O

R'

CH3 C

O

Cl

C

O

Cl

Acid Chloride Ester Amide acid anhydride

1-Nomenclature of acid chloride • Replace the -ic acid ending in the name of the parent acid by –yl chloride

IUPAC: Ethanoyl chloride Benzoylchloride Common : Acetyl chloride

Reactions of Acid Chlorides

R C

O

Cl+

OH2 R C

O

OH

+ ClH

R'OH R C

O

OR'+ ClH

NH3 R C

O

NH2

+ ClH

NH2R' R C

O

NHR'

+ ClH

R C

O

1) LiAlH4

2) H3O+ R CH2OH

AlCl3 + ClH

2- Nomenclature of esters

• The alkyl group (R’) is named first followed by the name of the parent acid with the ending –ate in place of –ic acid ending

• e.g.:

IUPAC: Ethyl ethanoate Methyl benzoate Common: Ethyl acetate

R O

O

R'

H3C OC2H5

O O

OCH3

Reactions of Esters

R C

O

OR'

+ OH2 R C

O

OH

+ R'OHH

+

R C

O

OR'

+ R''OH R C

O

OR"

+ R'OHH

+

R C

O

OR'

+ NH3 R C

O

NH2

+ R'OHH

+

R C

O

OR'

R CH2 OH + R'OH1) LiAlH4

2) H3O+

R C

O

OR'

R C OH

R"

R"

+ R'OH1) Dry ether

2) H3O++ 2 R"MgX

3- Nomenclature of amides• Replace the oic acid ending of the parent acid by amide word

IUPAC: Ethanamide Benzamide

Common: Acetamide

IUPAC: N,N-Dimethylmethamide N-Ethyl-N-methylbenzamide

Common:N,N-Dimethylformamide

CH3 C

O

NH2

C

O

NH2

H C

O

NCH3

CH3

C

O

NCH3

CH3

Reactions of Amides

R C

O

NH2

H3O+

R C

O

OH+ NH3

R C

O

NH2

NaOH/ heatR C

O

ONa+ NH3

R C

O

NH2

1) LiAlH4R CH2 NH2

2) H3O+

R C

O

NHR'

1) LiAlH4R CH2 NHR'

2) H3O+

R C

O

NH2

P2O5R C N

- H2O

R C

O

NH2

Br2 / NaOHR NH2

or NaOBr

4- Nomenclature of acid anhydrides• An anhydride is named by replacing the word acid by the word

anhydride in the name of the parent acid.

Ethanoic anhydride Benzoic anhydide Succinic anhydride

CH3 C

O

O C

O

CH3C

O

O C

O

O OO

Reactions of Acid anhydride

+

OH2 R C

O

OH

+ R'COOH

R'OH R C

O

OR'+ R'COOH

NH3 R C

O

NH2

+ R'COOH

NH2R' R C

O

NHR'

+ R'COOH

R C

O

1) LiAlH4

2) H3O+ R CH2OH

AlCl3 + R'COOH

R C

O

O C

O

R'

+ R'CH2OH

Occurrence and Uses of Occurrence and Uses of Carboxylic Acids and their Carboxylic Acids and their

DerivativesDerivatives• Carboxylic acids and their derivatives are widespread in nature

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C

OH

O

Butyric acid- a short chain fatty acid

C

C

OH

O

O

Pyruvic acid - a metabolite

S

SH

HN

H

C

O

O

CH3

CH3

COOHPencillin G (an antibiotic)

O

C

CH3

O

Isopentyl acetate (banana odour)

Carboxylic acids are used in the production of polymers, pharmaceuticals, solvents, and food additives.

Examples

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O

COH3C

C

O

OH

Acetyl salicylic acidaspirin(analgesic, antipyretic and

antiinflammatory)

H3CC

OH

O

Acetic acidin vinegar, organic solvent

C O

HOIbuprofenanalgesic and non sterodial anti-inflammatory drug for relief of arthritis

HO

OH

C

O

OH

H NH2

L-Dopa ( for treatment of parkinson's disease)