Transcript Presentation11_108

Carboxylic Acids and
Their Derivatives
By:
Dr. Shatha Alaqeel
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
2
Nomenclature of Carboxylic
Acid
General formula: R-COOH or Ar-COOH
In the IUPAC: 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.
O
H
C
O
O
OH
H3C
common Formic acid
IUPAC Methanoic acid
C OH
Acetic acid
Ethanoic acid
C2 H5
C
O
OH
Propionic acid
C3H7
C
O
OH
Butyric acid
C4H9
C
OH
Valeric acid
Propanoic acid Butanoic acid Pentanoic acid
In common : the position 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 .
In IUPAC: The carboxylic carbon is numbered 1.
CH3
COOH
H3C
H3C
common:
IUPAC:
-- Dimethyl butyric acid
2,3-Dimethyl butanoic 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.
HOOC
HOOC
COOH
COOH
Cyclopropane
Carboxylic acid
Cyclobutane
Carboxylic acid
COOH
Cyclopropanecarboxylic acid
Cyclopentane
Carboxylic acid
Cyclohexane
Carboxylic acid
COOH
CH(CH3)2
2-Isopropyl-cyclobutanecarboxylic acid
COOH
Br
Cl
2-Bromo-4-chloro-cyclopentanecarboxylic acid
COOH
NH2
5
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
common Benzoic acid
IUPAC Benzene carboxylic acid
Salicylic acid
2-Hydroxybenzenecarboxylic acid
COOH
COOH
COOH
COOH
common Phethalic acid
IUPAC Benzene-1,2-dicarboxylic acid
Terephtalic acid
Benzene-1,4-dicarboxylic acid
Physical Properties OF Carboxylic Acids
Solubility
Carboxylic acids are polar, they can form hydrogen bonds with water molecules


H
O
H-Bonds
H


C

H
O
H
O
R

O

H

Smaller carboxylic acids (1 to 4 carbons) are soluble in water
Whereas the solubility of bigger carboxylic acids decrease with size
Aromatic acids are insoluble in water
Boiling Points
 The boiling points of carboxylic acids indicate a greater degree
than alcohols
This is due to carboxylic acids usually exist as dimeric pairs by forming two
intramolecular hydrogen bonds in nonpolar media


O
H3C
H
C
O
H

O
C
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 donating 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.d. g.)
CH3CH2CH2CH(Cl)COOH > CH3CH2CH(Cl)CH2COOH > CH3CH(Cl)CH2CH2COOH >
CH2(Cl)CH2CH2CH2COOH ( position of e.w.g. relative to COOH group)
COOH
COOH
>
O2 N
NO2
COOH
>
NO2
COOH
>
>
COOH
9
Preparation Of Carboxylic acids
1- Oxidation Of Primary Alcohols
2- Oxidation Of Alkyl Benzenes
3- Carbonation Of Grignard Reagents
H 2O
H2O
4- Hydrolysis Of Nitriles
Reactions of Carboxylic Acids
1- Salts Formation
KOH or NaOH
RCOOH
- +
RCOO K or Na
-
+
NaHCO 3
RCOO Na
NH3
RCOO NH 4
COOH
+
-
+
+
H2 O
+
+ H2O
CO 2
+
-
COO Na
+
NaHCO 3
Sodium Benzoate
OH
+
NaHCO 3
N.R
2- Substitution of hydroxyl group
R'OH / H
+
RCOOR'
NH3
RCOOH
RCONH 2
SOCl 2
1) PCl 5
RCOCl
-
2) R''COO Na
+
Ester
Amide
Acid Chloride
RCOOCOR"
Anhydride
Carboxylic Acid Derivatives
O
R
C
R
Cl
OR'
Acid Chloride
ٌ
R
C
Ester
O
O
O
C
R
C
O
O
C
R'
N
Amide
acid anhydride
1-Nomenclature of acid chloride
Replacing the –ic acid ending of the parent acid by –yl chloride
O
O
H3C
C
Cl
C
Cl
Ethanoyl chloride
Acetyl chloride
Benzoyl chloride
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 –ic
acid:
O
O
H3C
C
OCH 3
C
OC 2H5
Ethyl ethanoate
Ethyl acetate
Methyl benzoate
3- Nomenclature of amide
Replacing the ending oic acid of the parent acid’s by amide
O
C
O
H3C
NH2
C
NH2
Ethanamide
Acetamide
Benzamide
O
O
H
C
C
CH3
N
CH3
N,N-Dimethylmethamide
N,N-Dimethylformamide
CH3
N
CH3
N-Ethyl-N-methylbenzamide
4- Nomenclature of anhydride
An anhydride is named by replacing the word acid by
anhydride.
O
H3C
C
O
O
O
C
O
CH3
Ethanoic anhydride
C
O
O
O
C
Benzoic anhydide Succinic anhydride
O
Reaction of Esters
O
R
O
+
+
C
H
H2O
R
+
C
OH
OR'
O
R
O
+
+
C
H
R''OH
R
O
+
+
H
NH3
R
R
1) LiAlH 4
C
2) H 3O
OR'
+
R
CH2 OH
+
R"
O
+
OR'
R'OH
NH2
O
C
+
C
OR'
R
R'OH
OR"
O
C
+
C
OR'
R
R'OH
2 R"MgX
1) Dry ether
2) H 3O
+
R
C
R"
OH
+
R'OH
R'OH
Acid Chlorides: Reactions
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
Acid anhydride: Reactions
O
H2O
R
+
C
R'COOH
OH
O
R'OH
R
+
C
R'COOH
OR'
O
O
R
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
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