Transcript Ch-9-Carboxylic acids and their derivatives-corr2 - Home

Dr Nahed Elsayed
1
Learning Objectives
Chapter nine introduces carboxylic acids and their derivatives. The chemistry is very
similar to that of aldehydes and ketones because of the presence of the carbonyl group .
The main topics in this chapter that the students should know and understand include:
The structure of carboxylic acids
The common and IUPAC nomenclature of carboxylic acids
The physical properties of carboxylic acids
The Factors affecting acidity of carboxylic acids.
The different ways to make carboxylic acids
Salt formation reactions of carboxylic acids
The nucleophilic substitution reactions at the carbonyl carbon and the specific
products formed in each case.
 The chemistry of carboxylic acid 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
 Carboxylic acids are classified as aliphatic R-COOH or aromatic
Ar-COOH depending on the group bonded to the carboxylic
group.
 The simplest aliphatic acid is formic acid R= H
 The fatty acid is long chain aliphatic acids CH3-(CH2)16-COOH
Nomenclature Of Carboxylic Acids
Common Nomenclature
Some carboxylic acids are called after characteristic properties or their origin.
All common names ending -ic acid
Formula
HCOOH
CH3COOH
CH3CH2COOH
CH3 (CH2)2COOH
CH3 (CH2)3COOH
Common name
formic acid
acetic acid
propionic acid
butyric acid
valeric acid
origin of name
Latin for ant
Latin for vinegar
Greek for milk
Latin for butter
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),
etc.

C
3

C
2
COOH
1
 Example of dicarboxylic acids
COOH
HOOC
Succinic acid
 Some aromatic acids have common names
COOH
COOH
OH
Benzoic acid
Salicylic acid
IUPAC Nomenclature
Find the longest continuous carbon chain contains the COOH group to get the
root name of the parent hydrocarbon, then replace the ending -e 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, positions and list them as prefixes
in alphabetical order.
Examples:
(CH3)2CH - CH(CH3) - CH2 - CH2 - COOH
4,5-Dimethylhexanoic acid
is called
O
C3H7
O
OH
Butanoic acid
C4H9
OH
Pentanoic acid
Br
NH2 O
O
OH
OH
HOOC
OH
3-Aminobutanoic acid
COOH
1,4-Butandioic acid
3-Bromo-2-hydroxy-4-hexenoic acid
 Cyclic compounds 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
Cyclopropanecarboxylic acid
COOH
CH(CH3)2
2-Isopropyl-cyclobutanecarboxylic acid
COOH
Br
Cl
2-Bromo-4-chloro-cyclopentanecarboxylic acid
COOH
NH2
3-Amino-cyclohexanecarboxylic acid
 Some aromatic compounds have common names accepted by the IUPAC also
they can be named as benzene carboxylic acids
COOH
COOH
OH
Benzene carboxylic acid
2-Hydroxybenzene carboxylic acid
COOH
COOH
Benzene-1,2-dicarboxylic acid
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Physical Properties OF Carboxylic Acids
Solubility
 Carboxylic acids are polar, they can form hydrogen bonds with water molecules


H
O
H-Bonds
H


R

H
O
H
O
C

O

H

 The first four aliphatic acids are completely miscible in water. Higher members
are less soluble
 Aromatic acids are insoluble in water
Boiling Points
 Carboxylic acids have exceptionally high boiling points than alcohols and
aldehydes, because their dimeric structures. of identical relative molecular
masses, For example:
Propanol
Ethanoic acid
M.F.
M.W
bp / °C
C 3H 8O
60.01
97.2
C 2 H 4 O2
60.05
118
O
R
HO
C
C
OH
O
Hydrogen-bonded acid dimer
R
Acid Strength
 Carboxylic acids are stronger acids compared to alcohols and phenols
 Electron withdrawing substituents near the carboxyl group increase the acidity
 Whereas electron donating substituents decrease the acidity .
 HCOOH > CH3COOH > CH3CH2COOH > CH3CH2CH2CH2COOH ( size of R
group)
 Cl3CCOOH > Cl2CHCOOH > ClCH2COOH > CH3COOH
withdrawing atoms)
COOH
COOH
>
O2 N
NO2
COOH
>
NO2
( number of electron
COOH
>
>
COOH
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Preparation Of Carboxylic acids
1- Oxidation Of Primary Alcohols
O
K2Cr2O7/H+
R CH2OH
R COH
or KMnO4/heat
Primary alcohol
carboxylic acid
O
O
K2Cr2O7/H+
R CH
aldehyde
or KMnO4/heat
R COH
carboxylic acid
2- Oxidation Of Alkyl Benzenes
CH3
KMnO4
COOH
KMnO4
COOH
Alkyl benzene
CH3
Toluene
Benzoic acid
CH2-CH3
KMnO4
COOH
+
Ethyl benzene
Benzoic acid
CO2 + H2O
3- Carbonation Of Grignard Reagents
R MgX +
O C O
O
Dry ether
H3O+
R
O
R
OH
OMgX
H3C MgX +
O C O
O
Dry ether
H3O+
H3C
O
H3C
OH
OMgX
4- Hydrolysis Of Nitriles
R X
NaCN
R C N
H3O+/ heat
or i) KOH
ii) H3O+
H3C Br
NaCN
H3C C N
H3O+/ heat
or i) KOH
ii) H3O+
R COOH + NH4+
H3C COOH + NH4Cl
Reactions Of Carboxylic Acids
1- Salts Formation
COOH
COO Na
NaHCO3
+ CO2
Sodium benzoate
+ H2O
2- Substitution Of Hydroxyl Group
General Equation
O
O
+
R
Examples
L
+
Nu
R
Nu
L
Carboxylic Acid Derivatives
O
R
C
R
Cl
Acid Chloride
R
C
OR'
Ester
O
O
O
C
R
C
O
O
C
R'
N
Amide
Acid anhydride
 The derivatives of carboxylic acids are compounds in which the OH of carboxylic acid is replaced by nucleopile (-X for acid halide,
-OR for ester, -NH2, -NHR, -NR2 for amids, -OOCR for anhydride).
 Carboxylic acids derivatives can converted to carboxylic acids by
simple acidic or basic hydrolysis.
Carboxylic Acid Derivatives
1-Nomenclature Of Acid Chlorides
 Replace the -ic acid ending in the name of the parent acid by –yl chloride
O
H3C
Cl
IUPAC: Ethanoyl chloride
Common : Acetyl chloride
O
O
Cl
CH3CH2
Benzoylchloride
C
Cl
Propanoyl chloride
2- Nomenclature of esters
 The alkyl group (R’) is written first followed by the name of the parent acid with
replacing of the ending –ic acid by –ate :
(IUPAC)
(common)
Ethyl ethanoate
Ethyl acetate
Methyl benzoate
O
O
HO
CH3CH2
C
OCH3
(IUPAC) Methyl propanoate
O
Isopropyl-4-hydroxy-5-methyl-5- hexenoate
3- Nomenclature of amide
 Replace the ending oic acid of the parent acid’s by the word
amide
If there is R group on the nitrogen atom, it is listed first and
designated with –N
O
CH3CH2
(IUPAC) Ethanamide
(common) Acetamide
Benzamide
(IUPAC) N,N-Dimethylmethamide
(Common) N,N-Dimethylformamide
C
NHCH3
N-Methylpropanamide
N-Methylpropionamide
N-Ethyl-N-methylbenzamide
4- Nomenclature of anhydride
 An anhydride is named by replacing the word acid
in the
corresponding acid by the word anhydride. Due to it is obtained
from corresponding acid by dehydration as shown in the
following equation:
O
O
OH
heat
O
OH
O
O
(IUPAC) Ethanoic anhydride Benzoic anhydride
Butandioic anhydride
(Common) Acetic anhydride
Succinic anhydride
Preparation of acid derivatives from acid chloride
O
CH3OH
OCH3
O
O
CH3NH2
Cl
NH-CH3
O
O
O
O
ONa
Reaction of Derivatives of carboxylic acid
 On hydrolysis (reaction with H2O/ H+) all carboxylic acid derivatives convert to
carboxylic acid.
O
R
H3O+
O
O
R
O
H3O+
R
O
O
R
O
R
H3O+
NH2
or eq NaOH/H3O+
O
R
Cl
H3O+
O
H
Questions
MgBr
1- Reaction of
with CO2 under heat and pressure gives:
COOH3
A)
COOH
B)
CH2OH
C)
COOH
D)
2- Oxidation of C6H5CH2OH with KMnO4 gives:
COOH
A)
CH2OH
COOH
B)
c)
CH2OH
D)
OH
NO2
3- The most acidic compound is?
A) CH3CH2CH2COOH
Cl
B) CH3CH2CH COOH
Cl
C) CH3CHCH2COOH
D) CH3CH2HC2COOH
O
4- The common name of this compound
CH3CH2
C
CH3
N
is?
CH3
A) N,N-Dimethylacetamide
C) N,N-Dimethylpropionamide
B) N,N-Dimethyl propanamide
D) N,N-Dimethylbutanamide
5- Acid halide react with ammonia to give?
A) Amines
B)Amides
C) Phenols
D) Alcohols
Questions?