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)