Download carboxylic acids

Carboxylic acids
@Fear secretes acids; but love and trust are sweet juices
by Mehmet OKUYUCU
1
CARBOXYLIC ACIDS
Contents
 Classification
Nomenclature
 Properties
 Preparation reactions
 Typical reactions
Some important acids
by Mehmet OKUYUCU
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Carboxylic Acids
Warm Up
• What is an acid and its properties?
• What is the importance of functional group in any
organic molecule ? Does it play an important role the
existence of funtional group in the molecule ?
• What are the organic acids? What are the differences
between organic and inorganic acids?
by Mehmet OKUYUCU
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REVIEW:FUNCTIONAL GROUP
(ID CARD)
The chemically reactive groups
of atoms within an organic
molecule. Some basic functional
groups are Hydroxyl, carbonyl,
carboxyl, amino so on
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• Chemistry Music Video 29- It_s A Family
Thing [www.keepvid.com].flv
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Introduction
• Compounds containing the carboxyl group (-COOH) are
called carboxylic acids.
O
C
O
H
O
• General formula R C OHor RCOOH or RCO2H
• R group can be aliphatic, aromatic or cyclic.
• Major organic acids found in fruits and vegetables.
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HERE ARE SOME EXAMPLES:
LEMON JUICE, VINEGAR, TOMATOES, COFFEE AND MILK TURN LITMUS
COLOUR RED INDICATING THE ACIDIC NATURE OF THESE SUBSTANCES
• Ascorbic acid (vitamin C, as from certain fruits)
• Acetic acid (Vinegar)
• Butyric acid (butter)
• Tartaric acid (Grape)
• Oxalic acid (Tomatoes)
• Formic acid(Ants)
• Malonic
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OKUYUCU
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1. Classification of Carboxylic Acids
1. According to the Number of Carboxyl Group
Monocarboxylic Acids
• Acids that contain only one carboxyl group.
O
O
H C OH
formic acid
H3C C OH
acetic acid
Polycarboxylic Acids
• Acids that contain more than one carboxyl group.
O H O
2
HO C C C OH
1,3-propanedioc acid
malonic acid
by Mehmet OKUYUCU
COOH
HOOC
COOH
Pentane, 1,3,5-tricarboxylic8 acid
A MINOR DETAIL
Skeletal formulae
In a skeletal formula, all the hydrogen atoms are removed
from carbon chains, leaving just a carbon skeleton with
functional groups attached to it.
For example, we've just been talking about butan-2-ol. The
normal structural formula and the skeletal formula look like
this:
In a skeletal diagram of this sort
there is a carbon atom at each junction between bonds in a
chain and at the end of each bond (unless there is something
else there already - like the -OH group in the example);
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1. Classification of Carboxylic Acids
2. According to the Functional Group
Hydroxy Acids
• Acids that contain hydroxyl group.
OH
COOH
H2C
oxyacetic acid
glycolic acid
OH
COOH
C
H
2-oxypropionic acid
lactic acid
H3C
Amino Acids
• Acids that contain amino group.
NH2
COOH
CH
2-aminopropionic
acid
by Mehmet OKUYUCU
alanine
H3C
NH2
COOH
H2C
amino acetic acid 10
glycine
1. Classification of Carboxylic Acids
Example 1
Classify the following acids as mono and poly carboxylic acid.
A.
COOH
B. COOH
COOH
COOH
Poly carboxylic acid
Mono carboxylic acid
C. COOH
D.
H2
C
H3C
COOH
CH
OH
by Mehmet OKUYUCU
Mono carboxylic acid
Mono carboxylic acid
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2. Nomenclature of Carboxylic Acids
1. Common Names
• Simple carboxylic acids known by common names.
H
CH3
C3H7
COOH
COOH
COOH
acetic acid
butyric acid
formic acid
COOH
COOH
COOH
benzoic acid
by Mehmet OKUYUCU
oxalic acid
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2. Nomenclature of Carboxylic Acids
2. Using The IUPAC System
• Number the longest carbon atom chain containing carboxyl
group starting from carboxyl carbon.
• Replace –e at the end of corresponding alkane by suffix –oic
and the word “acid”.
CH3
COOH
ethanoic acid
by Mehmet OKUYUCU
Br O
H3C
C
C
OH
CH3
2-bromo-2-methyl propanoic acid
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2. Nomenclature of Carboxylic Acids
2. Using The IUPAC System
• If the carboxylic acid contains more than one carboxyl group
-dioic acid or -trioic acid suffixes are used.
H2
HOOC C
COOH
propanedioic acid
malonic acid
CH3
COOH
COOH
ethanedioic acid
oxalic acid
HOOC
H2
C
CH
CH
COOH
COOH
butane-1,2,3-tricarboxylic acid
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2. Nomenclature of Carboxylic Acids
Example 2
Name the following carboxylic acids.
B. COOH
A.
COOH
H
C
H2C
Br
2-bromo cyclopropanoic acid
C.
H3
C
H2
C
H
C
C
CH3
H
C
NH2
COOH
NO2
CN
by Mehmet OKUYUCU
3-cyano-3-pentenoic acid
CH3
5-amino-3-methyl hexanoic acid
D.
COOH
H2
C
o-nitrobenzoic acid
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2. Nomenclature of Carboxylic Acids
Example 3
Write the structural formulae for the following compounds.
A. 4-amino hexanoic acid
B. 1,5-pentanedioic acid
C. 2-phenyl propanoic acid
D. 3-bromo-1,4-butanedioic acid
E. 3-aminocyclohexanoic acid
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3. Physical Properties of Carboxylic Acids
• The first members are colorless liquids with sharp or
unpleasant odors.
water insoluble
exceptions: four carbons or less
•
The first four members are soluble in water.
•Their solubilities and boiling points are higher
than alcohols with the same number of carbon.
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THE EFFECT OF HIGH BOILING POINT:DIMER FORMATION
polar + hydrogen bond  relatively high mp/bp
The carboxylic acid functional group
contains both a hydrogen bond donor (-OH) and a hydrogen bond
acceptor (C=O).
Carboxylic acids exist as hydrogen bonded dimers.
O
CH3
C
C
O H
by Mehmet OKUYUCU
H O
CH3
O
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COMPARING PHYSICAL PROPERTIES
Carboxylic acid
Alcohols
Aldehydes/Ketones
Ethers
Alkanes
by Mehmet OKUYUCU
Carboxylic acid
Alcohols
Aldehydes/Ketones
Ethers
Alkanes
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4.CHEMICAL PROPERTIES OF CARBOXYLIC ACIDS
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4. Chemical Properties of Carboxylic Acids
• 1.Acidity of Carboxylic Acids
• When carboxylic acids dissolve in water hydrogen ions are
formed and equilibrium is established.
R COOH(aq)+ H2O(aq)
R COO-(aq) + H3O+(aq)
+
[H
O
[R-COO ] 3 ]
-
Ka =
[R-COOH ]
• Both number and location of electro negative substituent
affect the acid strength.
• As the size of alkyl group increases, acidic property
decreases.
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4. Chemical Properties of Carboxylic Acids
2.Salt Formation
• Carboxylic acids react with active metals and form
carboxylate salts and hydrogen gas.
R-COOH + Na
HCOOH + Na
Formic acid
by Mehmet OKUYUCU
R-COONa + 1/2H2
HCOONa + 1/2H2
Sodium Formate
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4. Chemical Properties of Carboxylic Acids
3.Neutralization Reaction
R-COOH + NaOH
carboxylic
base
acid
HCOOH + NaOH
Formic acid
by Mehmet OKUYUCU
R-COONa + H2O
salt
HCOONa + H2O
Sodium Formate
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4. Chemical Properties of Carboxylic Acids
4.Esterification
O
R C
O
OH + R'- OH
carboxylic acid
H2SO4
alcohol
R C OR'+ H2O
ester
O
O
H3C
C OH + C2H5OH
acetic acid
ethanol
by Mehmet OKUYUCU
H2SO4
C O
C2H5 + H2O
ethyl acetate
H3C
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3. Chemical Properties of Carboxylic Acids
5. Reduction Reactions
• The reduction of carboxylic acids require strong reducing
agents like LiAlH4 or NaBH4.
• –COOH group is reduced to –CH2OH.
O
O
R C OH + 2[H]
O
LiAlH4
LiAlH4
R C H + 2[H]
RCH2OH
-H2O Aldehyde
primary alcohol
O
H3C C OH + 2[H] LiAlH4 H C C H + 2[H] LiAlH4
3
CH3CH2OH
-H
O
acetic acid
2
Acetaldehyde
ethyl alcohol
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4. Chemical Properties of Carboxylic Acids
6. Reactions Involving of C-O Bond Breakage
O
• R
C
group is called the acyl group. If a different
functional group is attached to the acyl group other than the
– OH group the compound is called an acid derivative.
Formation of Acid Anhydrades
• If a carboxylic acid is dehydrated acid anhyrades are
formed.
O
• The functional group of an acid unhydrade is
C
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O
O
C
TYPICAL COOH REACTIONS
Conversion to carboxylate salts
Conversion to acid halides
Conversion to esters
Conversion to amides
Conversion to anhydrides
Reduction to alcohols
Decarboxylation
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4. Chemical Properties of Carboxylic Acids
Example 5
Complete the following transformations.
+
H
A. CH COOH + CH CH OH →
3
3
2
B. CH3CH2COOH + PCl5 →
+
H
C. CH COOH + Br →
3
2
D. HCOOH + NaOH →
E. CH3CH2COOH + H2SO4 →
F. CH3CH2COOH + LiAlH4 →
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4. Chemical Properties of Carboxylic Acids
Solution
A.
O
+
CH3COOH + CH3CH2OH
H
H3C
C
O
C2H5 + H2O
ethyl acetate
O
B.
CH3CH2COOH + PCl5
H3C
H2
C
C
Cl + POCl3 + HCl
propoyl chloride
C.
CH3COOH + Br2
+
Br
O
H2C
C
H
OH
-bromo acetic acid
by Mehmet OKUYUCU
+ HBr
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4. Chemical Properties of Carboxylic Acids
Solution
D.
HCOOH + NaOH
E.
CH3CH2COOH + H2SO4
F.
CH3CH2COOH + 4[H]
by Mehmet OKUYUCU
HCOONa + H2O
O
H3C
H2
C
C
O
O
C
H2
C
propionic anhydride
LiAlH4
CH3CH2CH2OH
propyl alcohol
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CH3
5. Preparation of Carboxylic Acids
1. Oxidation of Primary Alcohols
• Oxidation of primary alcohols produces aldehydes and when
aldehydes are oxidized carboxylic acids are produced.
• KMnO4 and K2Cr2O7 solutions in acidic medium are used.
R-CH2-OH
1o alcohol
[O]
-H2O
[O]
C2H5OH
-H2O
by Mehmet OKUYUCU
O
O
C H
aldehyde
R
[O]
R
C OH
carboxylic acid
O
H3C C
HO
acetic acid
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5. Preparation of Carboxylic Acids
2. Hydrolysis of Carboxylic Acid Derivatives
O
R C OR' + H2O
H+
ester
O
H3C C OCH2CH3 + H2O
ethyl acetate
by Mehmet OKUYUCU
O
R C OH + HO-R'
carboxylic acid
+
H
alcohol
O
H3C C OH + HO-CH2CH3
ethyl alcohol
acetic acid
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5. Preparation of Carboxylic Acids
Example 6
Complete the following transformations below indicating
conditions and catalyst.
A. n-butanoic acid from n-butanol
B. 1, 6-hexanedioic acid from cyclohexene
C. benzoic acid from chlorobenzene
D. 1, 5-pentanedioic acid from 1,3-dichloropropane
E. acetic acid from ethyl acetate
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5. Preparation of Carboxylic Acids
Solution
A. n-butanoic acid from n-butanol
O
H2
C
HO
H2
C
C
H2
CH3
H2
C
2[O]
-H2O
H3C
n-butanol
C
C
H2
OH
butanoic acid
B. 1, 6-hexanedioic acid from cyclohexene
H2
C
KMnO4
HOOC
by Mehmet OKUYUCU
cyclohexene
H2
C
C
H2
COOH
C
H2
1,6-hexanedioic acid
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5. Preparation of Carboxylic Acids
Solution
C. benzoic acid from chlorobenzene
Cl
CN
NaCN
-NaCl
chlorobenzene
by Mehmet OKUYUCU
COOH
+ H2O
H+
benzoic acid
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5. Preparation of Carboxylic Acids
Solution
D. 1, 5-pentanedioic acid from 1,3-dichloropropane
H2
C
Cl
H2
C
C
H2
2NaCN
H2
C
Cl
-2NaCl
NC
1,3-dichloropropane
C
H2
H2
C
+4 H2O
H2
C
CN
HOOC
H+
H2
C
C
H2
COOH
1,5-pentanedioic acid
E. acetic acid from ethyl acetate
O
O
H2
C
H3C
C
O
CH3
by Mehmet
OKUYUCU
ethyl
acetate
+ H2O
H+
C
H3C
OH
acetic acid36
+ C2H5OH
6. Some Common Carboxylic Acids
1. Formic Acid, HCOOH
• First member and the simplest
carboxylic acids.
• Was obtained by the distillation of
ants.
• Soluble in water, colorless, pungent, fuming and corrosive
liquid.
• In its structure there are both aldehyde and carboxyl group. It
can react with Fehling’s and Tollens’ reagents.
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6. Some Common Carboxylic Acids
1. Formic Acid, HCOOH
• It is a good disinfectant, exists in honey to prevent spoiling,
used in textile dying, leather tanning, is a starting substance in
the production of fertilizers, rubbers and plastics and its
calcium salt is a good water softener.
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6. Some Common Carboxylic Acids
1. Formic Acid, HCOOH
• Prepared by following method in industry,
CO + NaOH
O
heat
pressure
H
C
O
H2SO4
ONa
H
C
OH + NaHSO4
• In laboratory,
COOH heat
HCOOH + CO2
formic acid
COOH
oxalic acid
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6. Some Common Carboxylic Acids
2. Acetic, CH3COOH
• Principal ingredient of
vinegar which has 4-6 % of
acetic acid and water.
• It is produced commercially by the oxidation of acetaldehyde,
and is also formed from the oxidation of ethyl alcohol.
• Soluble in water, and colorless.
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6. Some Common Carboxylic Acids
2. Acetic, CH3COOH
CH3CH2OH + O2
H C
C
acetylene
bacteria
H + H2O
O
H3C C
HgSO4
H2SO4
OH + H2O
O
CH3-C-H
acetaldeyde
[O]
O
CH3-C-OH
acetic acid
• It is an important substance for making textile fibers, vinyl
plastics.
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7. Dicarboxylic Acids
• They have two carboxyl groups.
• General formula is HOOC-(CH2)n-COOH
• All they have common names.
• Some of them are important monomers.
1. Oxalic Acid
• It occurs in beet leaves, sorrel, spinach, asparagus, tobacco,
and tomatoes.
• It is a white crystalline solid, its calcium salt precipitates in
kidneys.
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7. Dicarboxylic Acids
1. Oxalic Acid
• It is used as bleach in wood cellulose, hay, and feathers, and
in the manufacture of ink.
• Free oxalic acid is toxic and is used to remove stain from
fabrics and porcelain ware.
• Tomatoes are vegetables that contain oxalic acid and its
salts.
• Oxalic acid salts can be obtained from some plants, such as
asparagus.
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7. Dicarboxylic Acids
1. Oxalic Acid
COOH
COOH
heat
glycerine
oxalic acid
2HCOONa
HCOOH + CO2
formic acid
heat
sodium formate
COONa
+ H2
COONa
sodium oxalate
COONa
COONa
COOH
+ H2SO4
by Mehmet OKUYUCU
COOH
+ Na2SO4
oxalic acid
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7. Dicarboxylic Acids
2. Malonic Acid
• It was first obtained from malic acid (apple acid).
• It is colorless liquid, soluble in water and alcohol.
• It can be obtained from the hydrolysis of cyanoacetic acid.
COOH
COOH
+ 2H2O
H2C
CN
cyanoacetic acid
by Mehmet OKUYUCU
+ NH3
H2C
COOH
malonic acid
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7. Dicarboxylic Acids
3. Adipic Acid
• It was first obtained from oil.
• It is a solid, and produced from
the oxidation of cyclohexanol with
a nitric acid catalyst.
• Adipic acid is used in making of nylon.
H
%65 HNO3
OH
30-40oC
cyclohexanol
by Mehmet OKUYUCU
O
%65 HNO3
COOH
30-40oC
COOH
cyclohexanone
adipic acid
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8. Fatty Acids
1. Saturated Fatty Acid
•They are long chained carboxylic acids.
• Simplest fatty acid is
butyric acid, C3H7COOH
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47
8. Fatty Acids
1. Saturated Fatty Acid
Palmitic Acid, C15H31COOH
• It is a white crystalline solid, insoluble in water but soluble in
alcohol and ether.
• It occurs in palm oil,
beeswax and other animal
and vegetable fats and
oils.
by Mehmet OKUYUCU
48
8. Fatty Acids
1. Saturated Fatty Acid
Stearic Acid, C17H35COOH
• It is a crystalline solid, soluble in ether and hot alcohol.
• It occurs in the form of glycerides in
most animal and vegetable fats.
• Candles are a mixture of stearic
acid and palmitic acid.
by Mehmet OKUYUCU
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8. Fatty Acids
2. Unsaturated Fatty Acid
• Fatty acids containing carbon-carbon double bond on the
chain.
Oleic Acid, C17H33COOH
• It occurs in the form of glycerides in olive,
almond, cotton, and sunflower oils.
•It is colorless, tasteless, and odorless liquid.
•It is used in the production of lubricants,
detergents, resins and other products.
•Stearic acid is obtained by the addition of
by Mehmet
hydrogen
toOKUYUCU
oleic acid.
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8. Fatty Acids
2. Unsaturated Fatty Acid
Linoleic Acid, C17H31COOH and Linolenic Acid C17H29COOH
• They are found in the form of glycerides in vegetables oils
such as linseed, sesame and poppy oils.
•Linoleic acid has two and Linolenic acid has three double
bonds in alkyl chain.
by Mehmet OKUYUCU
51
Hope it has been helpful!!!
by Mehmet OKUYUCU
52