This document provides information about carboxylic acids and their derivatives. It begins by stating the learning outcomes, which are to provide nomenclature of carboxylic acids and derivatives, describe physical properties of carboxylic acids, and explain the synthesis and reactions of carboxylic acids and derivatives. The document then discusses the structure, naming rules, physical properties, acid strength, and synthesis methods of carboxylic acids. It also explains the nomenclature and reactions of common carboxylic acid derivatives like esters, acid halides, anhydrides, and amides.

1. 1
Carboxylic Acid
Their Derivatives
Jully Tan
School of Engineering
EP101 / EG101
Learning Outcome
At the end of this chapter, students are able to:
Provide nomenclature of the carboxylic acid its derivatives
Physical properties of carboxylic acid
Synthesis and reaction of carboxylic acid its derivatives

2. 2
Carboxylic Acids and Their Derivatives:
Nucleophilic Addition-Elimination at the Acyl Carbon
Carboxylic acids are a family of organic compounds with the
functional group
EP101 / EG101
O=
-C-OH
which is also written as -CO2H or COOH.
The carbon-oxygen double bond is made up of a s-bond and a p-bond.
The carbon atom is sp2 hybridized, which explains the trigonal planar
geometry at this center.
p
R C O
HO s
R may be alkyl, aryl or simply H
EP101 / EG101
Naming Rules
Uses the name of alkane that corresponds to the longest continuous chain of the
carbon atom.
The final –e in the alkane name is replaced by suffix –oic acid
The chain is numbered, starting with carboxyl carbon (COO-) atom as C1.
Position of the substituent is indicated by a number.
Acid which has C=O attached to ring are named by adding the name carboxylic
acid to the name of the cyclic compound.
When the acid has C=C in their structure, stereochemical term of cis and trans or E
and Z are used as they are with other alkenes.

3. 3
EP101 / EG101
IUPAC Names
Remove -e from alkane (or alkene) name, add -oic acid.
The carbon of the carboxyl group is #1.
Cl
CH3CH2CHC
OH
O
2-chlorobutanoic acid
Ph
C
H
C
H
COOH
trans-3-phenyl-2-propenoic acid
EP101 / EG101
Naming Cyclic Acids
Cycloalkanes bonded to -COOH are named as cycloalkanecarboxylic acids.
Aromatic acids are named as benzoic acids.
COOH
CH(CH3)2
2-isopropylcyclopentanecarboxylic acid
COOH
OH
o-hydroxybenzoic acid
COOH
NO2
Cl
2-Chloro-4-nitrobenzoic acid

4. 4
Physical Properties of Carboxylic acids
Carboxylic acids are polar protic molecules. They form strong
hydrogen bonds. One example of this is that they exist as dimers
in the liquid state.
EP101 / EG101
C
O
O-H
R
O
C
H-O
R
The boiling points are about
20 oC higher than alcohols of
comparable size.
Boiling Points
Higher boiling points than similar alcohols, due to dimer formation, resulting from the
association of two molecules of the acid, facilitated by hydrogen bonding.
Carbonyl compound have the following relative BP:
AmideCOOHnitrileester=acyl chloridealdehydeketone
EP101 / EG101

5. 5
EP101 / EG101
Solubility
Water solubility decreases with the length of the carbon chain.
Up to 4 carbons, acid is miscible in water.
More soluble in alcohol.
Also soluble in relatively nonpolar solvents like chloroform because it dissolves
as a dimer.
The Acid Strength of Carboxylic Acids
Carboxylic acids are weaker acids than mineral acids like HCl,
HNO3, or H2SO4, but they are more acidic than organic weak
acids such as aliphatic alcohols. Carboxylic acids are converted
into their carboxylate salts by aqueous solutions of hydroxide.
RCOOH HO-/H2O
H3O+
-
RCO2
Carboxylate anion
of resulting salt
Aqueous solutions of mineral acids convert the salts
back into the carboxylic acids.
EP101 / EG101

6. 6
A Comparison of the Acid Strength of
Carboxylic Acids and Alcohols
Carboxylic acids are considerably more acidic than alcohols in the
absence of special electronic influences.
RCOOH + H2O RCO2
- + H3O+ pKa ~ 5
ROH + H2O RO- + H3O+ pKa ~ 16
The enhanced acidity of carboxylic acids is attributed to the greater
stability of the carboxylate anion compared with the alkoxide anion,
which shifts the equilibrium more to the product side.
Resonance theory explains
this stability through two
equivalent resonance
R-C
structures that contribute to
the hybrid.
O .
. ..
..
..
O. .. ... O..
..- O..
.. O
..
R-C
-
R-C
1/2 -
.. O
..
1/2 -
X-ray analysis of sodium formate shows equivalent C-O bond
lengths of 1.27 A, consistent with this picture of a resonance hybrid. o
EP101 / EG101
Effect of Substituents on Acidity
Any factor that stabilizes the anion more than it stabilizes the acid
should increase acidity (decrease the magnitude of pKa). Any factor
that destabilizes the anion relative to the acid should decrease acidity.
- + H3O+
RCOOH + H2O RCO2
Electronic Influences
The electronic effect of a substituent G operates more strongly on the
anion (charged species) than on the carboxylic acid (neutral species).
EP101 / EG101
G C
O
O
-
Electron withdrawal
Stabilizes the anion and
increases acidity
G C
O
O
-
Electron release
Destabilizes the anion
and decreases acidity

7. 7
EP101 / EG101
Substituent Effects
on Acidity
Synthesis of Carboxylic Acids
EP101 / EG101
Oxidation of 1° ROH aldehydes
Side chain oxidation of alkylbenzenes
Conversion of Grignards.

8. 8
i) Oxidation of 1°ROH / Aldehydes
Aldehydes are easily oxidized to carboxylic acids, even by mild
oxidants such as Ag(NH3)2
+OH-, which is used in the Tollens' test for
distinguishing aldehydes from ketones. Stronger reagents such as
chromic acid (H2CrO4) or KMnO4 can oxidize either aldehydes or 1o
alcohols to carboxylic acids.
O
EP101 / EG101
O
R H
R OH
R OH
+OH-H2CrO4
Ag(NH3)2
or KMnO4
The alcohol is first oxidized to an aldehyde and then
to carboxylic acid
Oxidation of Alkylbenzenes
Vigorous oxidation by KMnO4 of primary and secondary (but not
tertiary) alkyl groups directly attached to a benzene ring produces
aromatic acids.
EP101 / EG101
CHRR'
(1) KMnO4, HO-, H2O
(2) H3O+
COOH
ii) Side chain oxidation of alkylbenzenes

9. 9
iii) Conversion of Grignards Reagent
Carbonation of Grignard Reagents
A more general way to prepare carboxylic acids from alkyl or aryl
halides is by carbonation (reaction with CO2) of the corresponding
Grignard reagents.
The strongly nucleophilic organomagnesium reagents add to CO2
to produce magnesium carboxylates. Acidification of these salts yields
the carboxylic acids.
- +MgX
::
H3O+
: :
R-C-OH
:O:
=
EP101 / EG101
d- d+
R-MgX
:O:
=
+ C
=
:O:
R-C-O
:O:
=
:
Nucleophilic
addition
All alkyl (1o, 2o, 3o) and aryl Grignard reagents undergo the
carboxylation reaction. This reaction is accomplished by either
bubbling dry gaseous CO2 through an ether solution of the Grignard
reagent or by pouring the Grignard reagent onto crushed dry ice
(solid CO2).
Syntheses Using the Grignard Carbonation Reaction
CH3
CH3
Mg
ether CH3C-MgCl
tert-Butylmagnesium
chloride
CH3
CH3
MgBr
COOH
H3C H3C
EP101 / EG101
CH3
CH3
CH3C-Cl
tert-Butyl
chloride
CH3C-COOH
2,2-Dimethyl-propanoic
acid
(1) CO2
(2) H3O+
Br
H3C CH3
CH3
Mg
ether
CH3
CH3
2,4,6-Trimethylphenyl-magnesium
bromide
CH3
CH3
2,4,6-Trimethylbenzoic
acid
(1) CO2
(2) H3O+
2,4,6-Trimethyl-bromobenzene

10. 10
Interconversion of Derivatives
More reactive derivatives
can be converted to less
reactive derivatives.
EP101 / EG101
Typical RCOOH Reactions
– Formation of Acid Derivatives
When the –OH of a carboxylic acid is replaced by nucleophile, :Nu, a
carboxylic acid derivatives is produced.
The carboxylic acid derivatives are:
O
R-C-X Amides
R-C-NH2
O
EP101 / EG101
O
O
R-C-O
O
Acyl (acid) halides
O
-C-R'
Acid anhydrides R-C-OR'
Esters
Another class of carboxylic acid

11. 11
Nomenclature of Acid Derivatives
Acid Halides
Replace the –ic acid suffix of carboxylic acids with –yl chloride.
If the acyl group is a branch of a cyclic compound, replace the ending from
O
EP101 / EG101
carboxylic acid to -carbonyl.
C
Cl
CH3CH2CH2C
O
Cl
butanoyl chloride
butyryl chloride
benzoyl chloride
Br
O
Benzoyl Bromide
Cyclohexanacarbonyl chloride
O
EP101 / EG101
Esters
The alkyl group (which replace of the hydrogen of the carboxylic acid) is named first
followed by the name of the parent acid, with the ending –ate in place of –ic acid
C
O CH2CH3
ethyl benzoate
O
O CH3
CH3CH2CH2C
methyl butanoate
methyl butyrate
Ethy 4-pentenoate Ethyl cyclohexanecarboxylate

12. 12
O O
EP101 / EG101
Acid Anhydrides
Anhydrides acids are named by replacing the word acid with anhydride.
H C O 3
Benzoic ethanoic anhydride
O
EP101 / EG101
Amides
An substituted –NH2 group is named by replacing the –oic acid of the carboxylic acid with –
amide and –carboxylic acid with –carboxamide.
A substituted compound is named by identification of the substituent followed by the
parent amide.
H C 3
O
NH2
ethylamide
C
NH2
CH3CH2CH2C
O
NH2
butanamide
butyramide
benzamide
N-metylbutanamide
Cyclohexanecarboxamide

13. 13
O
i) Formation of Ester
R C R C
OR'
O
R C OR'
O
O
R C OR'
EP101 / EG101
O
OH + R'OH
H+
+ HOH
acid
R C
O
Cl + R'OH + HCl
acid chloride
R C
O
O C
R + R'OH
H+
+ RCOOH
acid anhydride
O
O
O
+ R'OH
OH
EP101 / EG101
Reactions of Esters
O
R C
OR'
R C
OH + R'OH
R C
OR''
R C
NHR'' + R'OH
R CH2OH
R C
R''
R''
H2O
R''OH,
H+ or -OR''
R''NH2
(1)
(2) H2O
LiAlH4
(1) 2 R''MgX
(2) H2O
acid
ester
amide
1°alcohol
3°alcohol

14. 14
ii) Formation of Acid Halides
Synthesis of Acyl Chlorides
Because of their reactivity, acyl chlorides must be prepared under
conditions that exclude exposure to good nucleophiles like water.
Common reagents that convert carboxylic acids into acyl chlorides are
phosphorus trichloride (PCl3) phosphorus pentachloride (PCl5), and
thionyl chloride (SOCl2).
Typical Synthetic Procedures
The carboxylic acid is heated with the reagent, with or without the
presence of an inert solvent.
O=
+ SO2 + HCl
EP101 / EG101
O=
COH
Benzoic acid
or PCl3
+ SOCl2
Thionyl chloride
(bp 75-76 oC)
heat
CCl
Benzoyl chloride
Thionyl chloride is an especially convenient reagent because the
byproducts are gases and easily removed. Excess thionyl chloride is easy
to remove by distillation.
O
O
O
O
O
+ HCl
+ HCl
EP101 / EG101
Acid Chloride Reactions
H2O
R'OH
R'NH2
R'COOH
O
R C
Cl
R C
OH + HCl
R C
OR'
R C
NHR'
R C
O C
R' + HCl
acid
ester
amide
acid anhydride

15. 15
iii) Formation of Amides
Carboxylic acids react with aqueous ammonia to produce ammonium
carboxylates in an acid-base reaction:
O=
+
O=
EP101 / EG101
O=
RCOH
+ :NH3
Acid Base
RCO-
NH4
Ammonium carboxylate
Salt
Recovery of the ammonium carboxylate and heating of the dry salt leads to
dehydration and formation of the amide.
O=
RCO-
+
NH4
As the dry salt
RCNH2 + H2O
heat Amide
This method is generally not used in organic synthesis because the
vigorous heating required will often decompose the sample.
O
acid and amine
EP101 / EG101
Reactions of Amides
R C
OH + R'NH2
O
R C
NHR'
R CH2NHR'
H2O
H+ or -OH
(1)
(2) H2O
LiAlH4
Br-, OH-R
NH2 + CO2
POCl3
(or P2O5)
R C N
amine
1°amine
nitrile

16. 16
iv) Formation of Acid Anhydrides
The most general method for the preparing an acid anhydride is by nucleophilic
acyl substitution reaction of an acid chloride with a carboxylate anion.
EP101 / EG101
O
O
O
+ RCOOH
EP101 / EG101
Anhydride Reactions
O
R C
O
O C
R
R C
OH + RCOOH
R C
OR'
R C
NHR' + RCOOH
H2O
R'OH, H+
R'NH2
acid
ester
amide

17. 17
EP101 / EG101
Conclusion
At the end of the chapter…. You suppose able to:
Understand the nomenclature of carboxylic acid and its derivatives
The physical properties of carboxylic acid
The 3 main methods of synthesis carboxylic acid
The reaction of carboxylic acid to form its derivatives.