In this presentation You will get Acidity of phenols, Resonance , Qualitative test for Phenols, Uses And Structure Of phenols.

1. PHENOLS
BY ROHITKUMAR RATHI & GAURI TAJANE
FINAL YEAR B PHARM
GES’S SIR DR. M S GOSAVI COLLEGE OF PHARMACY,
NASHIK

2.  INTRODUCTION
• PHENOL is compound which contains directly attached hydroxyl
group to the carbon atom of benzene ring.
• Phenols also known as CARBOLIC ACID.
• Phenol is an aromatic organic compound with the
molecular formula C₆H₅OH.

3.  ACIDITY OF PHENOLS
• The acidity of phenols is due to its ability to lose
hydrogen ion to form phenoxide ions.
• Phenols react with active metals like sodium,
potassium to form phenoxide. This reaction of phenol
with metals indicates its acidic nature.
• Phenols react with aqueous sodium hydroxide too to
produce phenoxide ions. This indicates that
the acidity of phenols is higher in comparison to the
alcohols and water molecules.

4. • In a phenol molecule, the sp2hybridised carbon atom of the benzene ring
attached directly to the hydroxyl group acts as an electron-withdrawing
group.
• This sp2 hybridized carbon atom of a benzene ring attached directly to the
hydroxyl group has higher electronegativity in comparison to the hydroxyl
group.
• Due to the higher ELECTRONEGATIVITY of this carbon atom in
comparison to the hydroxyl group attached, electron density decreases on
the oxygen atom.
• The decrease in electron density increases the polarity of O-H bond and
results in the increase in ionization of phenols.
• Thus, the phenoxide ion is formed. The phenoxide ion formed is stabilized
by the delocalization of negative charge due to the resonance in the
benzene ring.
• Phenoxide ion has greater stability than phenols, as in the case of phenol
charge separation takes place during RESONANCE.

5.  RESONANCE OF PHENOL

6. • The resonance structures of phenoxide ions explain the
delocalization of negative charge. In the case of substituted
phenols, the acidity of phenols increases in the presence of the
electron-withdrawing group. This is due to the stability of the
phenoxide ion generated. The acidity of phenols further increases
if these groups are attached at ortho and para positions.
• This is due to the fact that the negative charge in phenoxide ion is
mainly delocalized at ortho and para positions of the attached
benzene ring. On the other hand, the acidity of phenols decreases
in the presence of electron-donating groups as they prohibit the
formation of phenoxide ion.

7.  EFFECTS OF SUBSTITUENTS ON ACIDITY
OF PHENOLS
• Electron-withdrawing substituents make a phenol more
acidic by stabilizing the phenoxide ion through
delocalization of the negative charge and through
Inductive effects. The effect of multiple substituents
on phenol acidity is additive.

8. • The effect of electron donating groups on a
phenol is to make it less acidic.

9.  QUALITATIVE TESTS FOR PHENOLS
Following test May be performed for Detection of phenolic group :-
(1) Solubility in sodium hydroxide :- Most phenols are soluble
in dilute NaOH but insoluble in NaHCO3.
(2) Ferric chloride test :- 6 C6H5 + FeCl3 H3 + { Fe(OC6 H5)6 } +
3 HCL

10. (3) Bromine water test :- Phenols react rapidly with bromine
water to produce insoluble substitution products; all available
position ortho and para to the phenol are brominated.

11. (4) Phthalein test :- On heating with phthalic anhydride in presence of
Conc. H2SO4, phenols produce condensation compounds which give a
characteristic colour in alkaline solution
(5) Lirbremann Nitroso Reaction
(6) Phenolate Test ( UV Visible/Spectroscopy)

12.  STRUCTURE & USES:-
(1) PHENOLS :-
Disinfectant & Antiseptic. The primary use of phenol is in
the production of phenolic resins, which are used in the plywood,
construction, automotive, and appliance industries. medicinal
products such as ear and nose drops, throat lozenges, and
mouthwashes. Phenols are widely used in household products and
as intermediates for industrial synthesis.

13. (2) CRESOL :-
Disinfectant & Antiseptic. Cresols are precursors or
synthetic intermediates to other compounds and materials,
including plastics, pesticides, pharmaceuticals, and dyes.
Most recently, Cresols have been used to create a
breakthrough in manufacturing carbon nanotubes.

14. (3) NAPTHOL :-
Antiseptic. Naphthol is used as colourants .It is
used to make medicines, specifically the
antifungal tolnaftate, naproxen, nafcillin and perfumes. It
also used in the synthetic rubber industry. In
pharmaceuticals Industry also.

15. (4) RESERSINOL :-
Disinfectant & Antiseptic. Resorcinol is used to make other
chemicals and pharmaceuticals such as acne creams, hair dyes and
sun tan lotions. As skin disorders and infections such as acne,
seborrheic dermatitis, eczema, psoriasis, corns, calluses, and warts.

16.  SYNTHETIC USES OF ARYL DIAZONIUM
SALTS
(1) They are useful in the synthesis of a large variety of organic
compounds, especially aryl derivatives. Ex: (C6H5) phenyl Functional
Group
(2) They find application in the dye and pigment industries and are
used to produce dyed fabrics.