chemistry - carboxylic acids and their reactions.

CARBOXYLIC ACIDS AND THEIR DERIVATIVES
Ms.R. DHIVYA
ASSISTANT PROFESSOR
DEPARTMENT OF CHEMISTRY
SRI SARADA NIKETAN COLLEGE OF SCIENCE FOR WOMEN,
KARUR

WHAT IS CARBOXYLIC ACIDS?
• A Carboxylic Acid is an organic compound containing a
carboxyl functional group.
• They occur widely in nature and are also synthetically
manufactured by humans.
• Upon deprotonation, carboxylic acids yield
a carboxylate anion with the general formula R-COO–
,
which can form a variety of useful salts such as soaps.

NOMENCLATURE
O
HO
H
methanoic
acid
O
HO
Propanoic acid
O
HO
Butanoic acid
O
HO
Benzoic acid
O
HO
(2Z)-3-phenylprop-2-enoic acid
O
HO
Ethanoic acid

ACID DERIVATIVES
O
Cl
O
Cl
acetyl
chloride
O
Cl
benzoyl
chloride
propanoyl
chloride
O
H2
N
O
H2N
acetamid
e
O
H2
N
O
H2N
butanamid
e
benzamid
e
propanamid
e
O
O
O
O
O
O
O
O
ethyl
benzoate
4
ethyl
acetate
ethyl
propanoate
ethyl
butanoate

DICARBOXILIC ACIDS
O
HO
O
OH
oxalic acid
O
HO
O
OH
propanedioic
acid
O
HO
O
OH
butanedioic
acid
O
HO
O
OH
(2E)-but-2-enedioic
acid
GENERAL PREPARATION METHODS
1. Oxidation of alcohols, aldehydes and ketones
CH3CH2OH CH3CHO CH3COOH
[O
]
[O
]
OH
HO
O
H
HO
O
+
[O
]
O
[O
]
2. Hydrolysis of cyanides and amides
3
CH CN 3
CH CONH2 3
CH COOH
3
H
O+
3
H
O+
C6H5SO3K +
KCN
C6H5C
N
5

3. Hydrolysis of esters
CH3COOC2H5 CH3COOH + C2H5OH
Δ
KOH
4. Hydroloysis of trihalgen derivates of alkanes
CHCl3
HCOOH
CH(OH) 3
Cl Cl
Cl
OH
HO
HO
OH
O
-H2O
5. Heating dicarboxylic acids
O O
HO OH
H
O
OH
Δ
6

6. Carbonatin of Grignard reagent
CH3MgBr + CO2 CH3COMgBr CH3COOH
O
O
7. Arndt-Eistert Synthesis
RCOOH + SOCl2
RCOCl RCOCHN2 RCH2COOH
2
3
Ag O, H
O+
RCOCHN2
CH2
N2
RCH2COOH
H2
O
EtO
H
RCH2COOC2H5
RCH2CONH2
NH3
RNH2
RCH2CONHR
SPECIAL METHODS OF PREPARATION OF AROMATIC ACIDS
1. Oxidation of alkyl benzene
O OH
KMnO4
7

2. Friedel Craft reaction
O
CH3COCl
AlCl3
COCl2
AlCl3 O
3. Hydrolysis of Benzotrichloride
Cl
Cl
Cl
OH
HO
HO
OH
O
-H2O
4. Kolbe Reaction
OH
CO2
NaO
H
OH O
OH
8

PROPERTIES
1. The first three members are colourless, pungent smelling liquids. C4 to C8 have
unpleasant odours. Acids above C7 have no smell.
2. Carboxylic acids are free soluble in water due to hydrogen bonding with water molecule
3. Boiling points of acid lower member are higher than alcohols of comparable molecular
masses.
4. The even member carbon have markedly high melting points than the odd member
preceding or following acid.
5. Acidity of carboxylic acid and substituent’s on acidity
REACTIONS OF CARBOXYLIC ACIDS
A. INVOLVING HYDROGEN ATOM OF COOH GROUP
Reaction with metals
CH3COOH +Na
CH3COOH +Ca
CH3COOH +Ca
CH3COONa + 1/2 H2
(CH3COO)Ca + 1/2 H2
(CH3COO)Ca + 1/2 H2
CH3COOH +NaHCO3 CO2 + H2O + CH3COONa
CH3COOH +NaOH
C6H5COOH +NaOH
CH3COONa + H2O
C6H5COONa + H2O
9

B. INVOLVING –OH OF THE –COOH GROUP
i. Reaction with Alcohols (Breakage of Carbonyl and oxygen of –COOH
group)
O
O
H
H O
+
O
O
H
H O
+
not
occur
occur's
1
RCOOH + R OH
1
RCOOR + H2O
anhydrous
ZnCl2
H
SO
2 4
CH3COOH + CH3OH CH3COOCH3 + H2O
anhydrous
ZnCl2
H
SO
2 4
6 5 2 5 6 5 2 5 2
C H COOH + C H OH C H COOC H + H O
Decreasing reactivity order of alcohol
CH3OH > C2H5OH > (CH3)2CHOH > (CH3)3OH
Decreasing reactivity order of acid
HCOOH > CH3COOH> C2H5COOH > (CH3)3COOH
H+
O OH O OH O OH
Decreasing reactivity order of
acid
10
> >

ii.
+ HCl + POCl3
Rection with PCl5, PCl3 or SOCl2
CH3COOH + PCl5
CH3COCl
CH3COOH + PCl3 CH3COCl
+ H3PO3
CH3COOH + SOCl2
C6H5COOH + SOCl2
CH3COCl
C6H5COCl
+ SO2 + HCl
+ SO2 +
HCl
iii. Reaction with ammonia
RCOOH + NH3
RCOONH4
RCONH2 + H2O
Δ
HCOOH + NH3 HCOONH4 HCONH2 + H2O
Δ
C6H5COOH + NH3 C6H5COONH4 C6H5CONH2 + H2O
Δ
iv. Dehydration
2CH3COOH CH3COOCOCH3
2C6H5COOH C6H5COOCOC6H5
P2O5
O
O
O
C. INVOLVING –C=O GROUP OF –COOH GROUP
Reduction
RCOOH + LiAlH4
RCH2OH
11

D. INVOLVING ALKYL GROUP OF THE ACID
Hell-Volhard-Zelinsky Reaction (HVZ reaction)
O
O H
O
O
H
Cl
Cl2
Alc. KOH
O
O
H
KCN
O
O
H
NC
Aq.
KOH
O
O H
HO
E. DECARBOXYLATION
O
O
H
O
3 keto pentanoic acid
Δ
O
+
O
O
O
O H
Δ
+
O
O
12

+
N
O
– O
+
N
OH
O
O
+
O
– N
O
F. SALTS OF CARBOXYLIC ACID
O
+
N
O
–
+
N
O
+
O
– N
O
Δ
O
O H
CaO
NaOH
O
–
O Na
+
O
O H
Ag2O, Br2,
Δ
Br
13

ACID CHLORIDES
O
O H
O
R
1
= X, NH2, OCOR, OR
Preparation: These are prepared by treating caroxylicl acid with SOCl2, PCl5 and PCl3.
CH3COOH + PCl5 CH3COCl + HCl + POCl3
CH3COOH + PCl3
CH3COOH + SOCl2
CH3COCl
CH3COCl
+ H3PO3
+ SO2 +
HCl
C6H5COOH + SOCl2 C6H5COCl + SO2 +
HCl
Chemical Reactions
1. Nucleophilic substitution
Cl
O
H2O
O
OH
-HCl
O
C2
H5
OH
Cl
O
O
O
Cl
O
NH2
NH3
14

O
Cl
O
NHNH2
N2H4
O
NH2OH
Cl
O
NHOH
2. Reduction
O
Cl
LAH
OH
O
H
15

3. Friedel-Craft reaction
O
CH3COCl
AlCl3
COCl2
AlCl3 O
4. Diazomethane
O
N2
O
O
Cl
CH2N2
Ag2O
O
OH
H2O
16

ACETIC ANHYDRIDE
Preparation
O
Cl
Pyridine
CH3COON
a
O O
O
O
OH
P2O5
Δ
O O
O
O
OH
O
OH
Δ
O
O
O
O
OH
O
OH
O
O
O
Δ
17

chemistry - carboxylic acids and their reactions.

chemistry - carboxylic acids and their reactions.

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