Carboxylic Acid

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Carboxylic Acid
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A. Preparation

• 1. Oxidation of primanry alcohol

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A. Preparation

• 2. From acid nitrile

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A. Preparation

• 3. For aromatic acid

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B. Physical properties

• 1. The boiling point and melting point are higher
  than corresponding ester due to the existence of
  H-bond between the molecules of acid. Lower
  members of aliphatic acids are liquid with
  pungent smell.
• 2. Lower members of aliphatic acids are soluble
  in water due to the formation of extensive H-bond
  with water molecules.

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B. Physical properties

• 3. Molecular mass of acids is found to be doubled
  when dissolved in benzene due to the formation of
  dimer via H-bond formation.

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C. Chemical Properties

• 1. Acid character

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C. Chemical Properties

• 1. Acid character (contd)

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C. Chemical Properties

• 1. Acid character (contd)Carboxylic acid is
  more acidic than alcohol and phenol due to the
  comparatively more stable carboxylate anion than
  alkoxide and phenoxide ion. The equilibrium
  position thus lie closer to the right hand side.

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C. Chemical Properties

• 1. Acid character (contd)The resulting
  resonance hybrid of the carboxylate anion is more
  stable than that of phenoxide ion due to the
  equal contribution of the two canonical forms.On
  passing up the homologous series, the members
  become less acidic since alkyl group is electron
  donating which makes the negative charge on the
  resulting carboxylate anion to be more
  intensified and thus less stable.

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C. Chemical Properties
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C. Chemical Properties

• 1. Acid character (contd)
• Chlorine replacing hydrogen in alkyl group of
  the acid causes the acid to be more acidic since
  the chlorine has an negative inductive
  effect.This causes the negative charge in the
  carboxylate anion to be spread through the ion
  more effectively, i.e. more stable.

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C. Chemical Properties

• 2. Esterification

Forward reaction is an acid-catalyzed
esterificationwhile the backward reaction is
acid-catalyzedhydrolysis of ester.
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C. Chemical Properties

• 2. Esterification (contd)
• SaponificationIn alkaline medium (hydrolysis
  of ester).(Not a equilibrium reaction)

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C. Chemical Properties

• 3. Reduction

LiAlH4 is a very strong reduction agent
(especially in organic compound). N.B. NaBH4
cannot reduce carboxylic acid.
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C. Chemical Properties

• 4. Replacement of OH by -X

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C. Chemical Properties

• 5. Formation of amide

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C. Chemical Properties

• 6. Decarboxylation

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C. Chemical Properties

• 7. Chlorination

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C. Chemical Properties Special reaction for
methanoic acid

• 1. Oxidation

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C. Chemical Properties Special reaction for
methanoic acid

• 2. Dehydration

How can you test CO?
1. turn citrated blood cherry red.2. burn with
blue flame the gas turn limewater milky.
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C. Chemical Properties Special reaction for
methanoic acid

• 3. Decomposition by heating

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C. Chemical Properties Special reaction for
methanoic acid

• 4. With neutral FeCl3

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Ethanedioic acid (Oxalic acid)

• A. Preparation
• 1. Oxidation of ethene

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Ethanedioic acid (Oxalic acid)

• A. Preparation
• 2. Ozonolysis of ethyne

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Ethanedioic acid (Oxalic acid)

• B. Physical Properties1. It is a colourless
  solid.2. It is quite soluble in water.

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Ethanedioic acid (Oxalic acid)

• C. Chemistry Properties1. As an acid2.
  Formation of acid chloride3. Formation of ester

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Ethanedioic acid (Oxalic acid)

• c. Chemistry Properties4. With oxidising agent

It is used as a primary standard involumetric
analysis.
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Ethanedioic acid (Oxalic acid)

• c. Chemistry Properties5. With conc. sulphuric
  acid

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Butenedioic acid
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Butenedioic acid

• A. Difference in physical porperties

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Butenedioic acid

• A. Difference in physical porperties (contd)

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Butenedioic acid

• B. Reasons for the differences
• 1. Melting point
• Melting involves the breaking of intermolecular
  bond. The cis-isomer has intramolecular H-bond
  since the acid group are close together and this
  reduce the extent of formation of intermolecular
  H-bond.

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Butenedioic acid

• B. Reasons for the differences
• 1. Melting point (contd)

Trans-isomer can form intermolecular H-bond only
since the 2 acid groups are too far apart.Also,
packing of the molecules in trans-isomer is
better as it has a more symmetrical structure.
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Butenedioic acid

• B. Reasons for the differences
• 2. Density
• The intermolecular force in cis-isomer is weaker
  and so molecules are packed less closely
  together, leading to lower density than the
  trans-isomer.

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Butenedioic acid

• B. Reasons for the differences
• 3. Solubility
• Since intermolecular force in cis-isomer is
  weaker, it is more easily broken on adding to
  water and thus more soluble. In cis-isomer,
  there is a net dipole moment, it is thus more
  soluble in a polar solvent.

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Butenedioic acid

• B. Reasons for the differences
• 4. Acidity
• Ka1 for trans-isomer is smaller than that of
  cis-isomer. In cis-isomer, after the first
  proton is released, the anion exists in resonance
  which causes it to be more stable than that of
  trans-isomer. And thus the equilibrium position
  shift to the right hand side.

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Butenedioic acid

• B. Reasons for the differences
• 4. Acidity (contd)

But on releasing the second proton, such
extrastability may be lost and therefore Ka2 is
smallerfor cis-isomer.
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Butenedioic acid

• C. Difference in chemical properties

The ease of formation of acid anhydride indicates
that maleic acid is the cis-isomer.Since the
CC bond cannot be rotated, the twoacid groups
in trans-isomer are not close enough to lose a
molecule of water in the same way.