Class 12 Chemistrty

1. Phenol
Govinda Pathak
Chemistry Lecturer
Samakhusi, Kathmandu 44600
Nepal
Email: Pathakgovinda32@gmail.com

2. Phenol
Phenol is an aromatic compound. The chemical
formula of this organic compound is C6H6O.
Phenol is also known as Carbolic acid. It consists
of a hydroxyl group and a phenyl group attached
to each other. It considerably dissolves in water.

3. Phenol
• General Properties of Phenol
• The molecular formula of phenol is
C6H5OH and molecular mass 94.113 amu.
• It is a transparent crystalline solid with a
sweet and tarry odour.
• The density is 1.07 grams per centimeter
cube, melting point is 40.5 °C and boiling
point is 181.7 °C

4. Nomenclature of Phenol
If –OH group is attached to the side chain of an aromatic
ring then it isn’t considered as Phenol. This type of
compounds are known as aromatic alcohol. E.g.

5. Question
• Write there method for preparation of
phenol. Write action of method with
a. Zn metal
b. Phthalic anhydride
c. CHCl3/KOH

6. 1.From Diazonium Salt (Laboratory method)
• Phenol is prepared in the laboratory by warming
aq. solution of benzene diazonium chloride.

7. 2.From Chlorobenzene (Dow’s process)
• Chlorobenzene when heated with aq. solution of
NaOH (or Na2CO3) at about 350o
C under 300
atmospheric pressure gives sodium phenoxide
which upon acidification gives phenol.

8. 2.From Chlorobenzene (Dow’s process)

9. 3.From Methoxy Benzene(anisole)
• Methoxy benzene when heated with
HI gives phenol

10. a)
1. When phenol is heated with zinc dust,
benzene is formed.

11. b)
2. Phenol react Phthalic anhydride to
give phenolphthalein. This
phenolphthalein is used as indicator
during laboratory work.

12. b)
3. When phenol is refluxed with chloroform
and aq. NaOH at 600
C, a mixture of o
hydroxybenzaldehyde and p-
hydroxybenzaldehyde is obtained. This
reaction is called Reimer-Tiemann
reaction.

13. Question
• What happened when phenol is heated with
i. Formaldehyde
ii. Azobenzene
• Answer
• Phenol react with formaldehyde to form bakelite.
OH
+ H C H
O

14. Question

15. Coupling Reaction
• Phenols react with benzene diazonium chloride in
slightly alkaline medium and at low temperature to
form coloured compounds called azo dyes. This
reaction is called coupling reaction.

16. Phenol
• An aromatic hydrocarbon (A) is used to manufacture
phenol by reacting with air at high temperature in
presence of minerals acid. (8 marks)
a. Write the IUPAC name and common name of
hydrocarbon(A).
b. Write the series of reaction to convert (A) to phenol.
c. Convert phenol into i) picric acid ii) p cresol and iii)
phenolphthalein
d. Write the colour of product when phenol react with a) FeCl3
b) aq Br2
e. Draw the structure of an antiseptic Dettol.

17. Phenol
• The IUPAC and Common name of that aromatic
hydrocarbon is Isopropyl benzene(cummene).

18. Phenol
• Oxidation of cumene in presence
of Sulphuric acid give phenol.

19. Phenol
OH OH
Conc. HNO3
NO2
NO2
+ 3H2O
NO2
OH
H
H
CH3-Cl
AlCl3
OH
CH3
+
OH
CH3

20. Structure of Dettol
• Structure of Dettol

21. Some Important Short
Question Related to Phenol.
1. Phenol is more acidic than alcohol.
2. Phenol is slightly soluble in water but alcohol is
highly soluble in water.
3. –OH group of phenol is ortho and para directing
towards electrophilic substitution reaction.
4. Phenol has higher boiling point than arene and
haloarene of comparable molecular mass.
5. 2,4,6-trinitrophenol is more acidic than phenol.
6. Picric acid reacts with NaHCO3 or Na2CO3 but
phenol can’t

22. 1. Answer

23. 2. Answer
• Phenols are slightly (sparingly) soluble in water
though it can form intermolecular H-bond with
water molecules. Limited solubility is mainly due
to hydrophobic nature of benzene ring.

24. 3. Answer

25. 4. Answer
• The melting and boiling points of phenols are higher
than the arenes and holoarenes of comparable
molecular masses. This is due to the presence of
intermolecular H-bond between phenol molecules.

26. Resonating Structure of
Phenol & Phenoxide Ion

27. Transforming Education