Transcript Ch-9-Carboxylic Acids and their derivatives new

Carboxylic Acids and
Their Derivatives
By
Dr. Nahed Nasser
CARBOXYLIC ACIDS
CONTENTS
• Structure of carboxylic acids
• Nomenclature
• Physical properties of carboxylic acids
• Preparation of carboxylic acids
•Reactions of carboxylic acids
•Derivatives of carboxylic acids:
a. Acid chlorides
b. Esters
c. Amides
d. Anhydrides
•Occurrence and uses of carboxylic acids and their derivatives
STRUCTURE 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
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NOMENCLATURE Of CARBOXYLIC ACIDS
IUPAC 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:
(CH3)2CH - CH(CH3) - CH2 - CH2 - COOH
4,5-Dimethylhexanoic acid
is called
• 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.
COOH
COOH
Cyclopropanecarboxylic
acid
CH(CH3)2
2-Isopropyl-cyclobutanecarboxylic acid
COOH
COOH
Br
NH2
Cl
3-Amino-cyclohexanecarboxylic acid
COOH
2-Bromo-4-chloro-cyclopentanecarboxylic acid
COOH
COOH
OH
Benzene
carboxylic acid
2-Hydroxybenzene carboxylic acid
COOH
Benzene-1,2-dicarboxylic acid
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Common nomenclature of carboxylic acids
• Some carboxylic acids are called after characteristic properties or their
origin.
Formula
HCOOH
CH3COOH
CH3CH2COOH
CH3 (CH2)2COOH
CH3 (CH2)3COOH
IUPAC name
methanoic acid
ethanoic acid
propanoic acid
butanoic acid
pentanoic aic
Common name origin of name
formic acid
Latin for ant
acetic acid
Latin for vinegar
propionic acid Greek for milk
butyric acid
Latin for butter
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-COOH
6 54 3 2 1
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CH3
COOH
H3C
H3C
common:
IUPAC:
-- Dimethyl butyric acid
2,3-Dimethyl butanoic acid
• Some aromatic acids have common names.
COOH
COOH
COOH
COOH
COOH
OH
COOH
Benzoic acid
Salicylic acid
Phthalic acid
Terphathalic acid
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PHYSICAL PROPERTIES OF CARBOXYLIC ACIDS
Solubility
• Carboxylic acids are polar, they can form hydrogen bonds with
H
water molecules

O
H-Bonds

H
H

O
O

H
C
R

O
H
• 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
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Boiling Points
• 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


O
H3C
H
O
C
C
O
H

O

Hydrogen bond
CH3
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 near the carboxyl group increase
the acidity
Whereas electron releasing substituents decrease the acidity .
• 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
•
O2N
COOH
COOH
COOH
>
>
NO2
NO2
>
COOH
>
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CH3
Preparation of Carboxylic acids
1- Oxidation of primary alcohols or aldehydes
+
H2Cr 2O 7 or K 2Cr 2O 7/ H
R
CH2
O
OH
R
or KMnO 4 / heat
C
OH
carboxylic acid
Primary alcohol
+
H2Cr 2O 7 or K 2Cr 2O 7/ H
R
CH
O
O
R
or KMnO 4 / heat
Aldehyde
C
OH
carboxylic acid
2- Oxidation of Alkylbenzenes
CH3
COOH
KMnO
Toluene
4
Benzoic acid
CH
2 CH 3
COOH
KMnO
4
+
Benzoic acid
CO
2
+
H 2O
3- Carbonation of Grignard Reagents
H2O
H2O
4- Hydrolysis of nitriles
R-X
NaCN
+
R
C
N
H3O / heat
RCOOH
+
+
NH4
Reactions of Carboxylic Acids
1- Salts Formation
KOH or NaOH
RCOOH
- +
RCOO K or Na
-
+
NaHCO 3
RCOO Na
NH3
RCOO NH 4
-
+
+
H2 O
+
+ H2O
CO 2
+
-
COO Na
COOH
+
+
NaHCO 3
Sodium Benzoate
OH
+
NaHCO 3
N. R
2- Substitution of hydroxyl group
R'OH / H
NH3
RCOOH
SOCl2
1) PCL5
2) R''COO Na
RCOOR'
Ester
RCOO NH4
Salt of acid
RCOCl
Acid chloride
RCOOCOR'' Anhydride
Carboxylic Acid Derivatives
O
R
C
R
Cl
R
C
OR'
Acid Chloride
Ester
O
O
O
C
R
C
O
O
Amide
acid anhydride
O
H3C
IUPAC:
Common :
C
Cl
C
Cl
Ethanoyl chloride
Acetyl chloride
R'
N
1-Nomenclature of acid chloride
• Replace the -ic acid ending in the name of the parent acid
by –yl chloride
O
C
Benzoylchloride
Reactions of Acid Chlorides
O
H2O
R
+
C
HCl
OH
O
R'OH
R
+
C
HCl
OR'
O
O
R
R
NH3
Cl
HCl
NH2
+
C
+
C
O
NH 2R'
R
+
C
HCl
NHR'
O
AlCl 3
R
C
1) LiAlH 4
2) H 3O
+
R
CH 2OH
+
HCl
Reactions of Esters
O
R
O
+
+
C
H
H2O
R
+
C
OH
OR'
O
R
O
+
+
C
H
R''OH
R
O
+
+
C
H
NH3
R
O
C
OR'
1) LiAlH 4
2) H 3O
R
+
CH2 OH
+
R'OH
R"
+
OR'
R'OH
NH2
O
C
+
C
OR'
R
R'OH
OR"
O
R
+
C
OR'
R
R'OH
2 R"MgX
1) Dry ether
2) H 3O
+
R
C
R"
OH
+
R'OH
Reactions of Amides
O
R
H3O
C
O
+
R
+
C
NH2
OH
O
R
O
NaOH/ heat
C
R
ONa
O
1) LiAlH 4
C
NH2
O
R
NHR'
O
C
NH2
O
R
2) H 3O
+
1) LiAlH 4
C
R
+
C
NH2
R
NH3
C
NH2
2) H 3O
+
P 2O 5
R
CH2 NH2
R
CH2 NHR'
R
C
N
- H 2O
Br 2 / NaOH
or NaOBr
R
NH2
NH3
R
Reactions of Acid anhydride
O
H2O
R
+
C
R'COOH
OH
O
R'OH
R
+
C
R'COOH
OR'
O
O
C
O
C
R
NH3
O
R'
R'COOH
+
C
NH2
+
O
NH 2R'
R
+
C
R'COOH
NHR'
O
AlCl 3
R
1) LiAlH 4
2) H 3O
+
R
+
C
CH 2OH
+
R'CH 2OH
R'COOH
Occurrence and Uses of
Carboxylic Acids and their
Derivatives
• Carboxylic acids and their derivatives are widespread in
nature
O
O
C
C
OH
C
OH
O
Pyruvic acid - a metabolite
Butyric acid- a short chain fatty acid
C
H
N
H
S
O
CH3
O
C
SH
CH3
O
Pencillin G (an antibiotic)
COOH
O
CH3
Isopentyl acetate
(banana odour)
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Carboxylic acids are used in the production of polymers,
pharmaceuticals, solvents, and food additives.
Examples
H3C
O
C
O
C
C
OH
HO
Ibuprofen
analgesic and non sterodial anti-inflammatory
drug for relief of arthritis
O
Acetyl salicylic acid
aspirin(analgesic, antipyretic and
antiinflammatory)
O
O
C
OH
H
O
NH2
C
H3C
OH
Acetic acid
in vinegar, organic solvent
HO
OH
L-Dopa
( for treatment of parkinson's disease)
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OH
N
N
H2N
N
H2 H
C N
O
H COOH
C N CH
CH2CH2COOH
N
folic acid
H2N
COOH
p-aminobenzoic acd
PABA
H2N
SO2NH2
sulfanilamide
Antibiotic ‘’ Magic bullet’’
•
Sulfanilamide It eliminates bacteria that cause infections by stopping the production of folic
acid inside the bacterial cells
•
Para-amino benzoic acid, more commonly known as PABA, is a non-protein amino acid widely available
in nature. It can be found in food sources such as liver, eggs (whole), molasses, rice, wheat germ and
spinach. PABA is often referred to as Vitamin Bx (part of the Vitamin B complex family) and it has been
suggested to contribute to a lot of processes in the body and it marketed as PABA vitamin..
Most Popular Use of PABA: PABA is widely used as a topical sunscreen (i.e. Sunscreen with PABA), as it
has the ability to absorb UV rays from the sun ; it is considered as antioxidant, it has been found to reduce
wrinkles and even to restore gray hair to its original color, further more play a role in red cells formation and
manufacturing of folic acid, may play a role in reducing fatigue and limiting the effects of depression.
•
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