This document discusses alcohols, phenols, and ethers. It defines that alcohols contain hydroxyl groups attached to carbon atoms in aliphatic compounds, while phenols have hydroxyl groups attached to aromatic systems. Ethers are formed when a hydrogen atom in a hydrocarbon is replaced by an alkoxy or aryloxy group. Alcohols and phenols can be classified based on the number of hydroxyl groups as mono-, di-, tri-, or polyhydric. The document also discusses the structures and preparations of these compounds.

1. CBSE Class 12 Chemistry
Alcohols, Phenols and Ethers

3. Alcohols and phenols are formed when a hydrogen atom in a hydrocarbon, aliphatic and
aromatic respectively, is replaced by –OH group.
An alcohol contains one or more hydroxyl (OH) group(s) directly attached to carbon atom(s), of
an aliphatic system (CH3OH) while a phenol contains –OH group(s) directly attached to carbon
atom(s) of an aromatic system (C6H5OH).
Spirit used for polishing wooden furniture is chiefly a compound containing hydroxyl group,
ethanol. The sugar we eat, the cotton used for fabrics, the paper we use for writing, are all made
up of compounds containing –OH groups.
The substitution of a hydrogen atom in a hydrocarbon by an alkoxy or aryloxy group (R–O/Ar–
O) yields another class of compounds known as ‘ethers’.

4. Alcohols and phenols may be classified as mono–, di–, tri- or polyhydric compounds depending
on whether they contain one, two, three or many hydroxyl groups.
Monohydric alcohols may be further classified according to the hybridisation of the carbon atom
to which the hydroxyl group is attached.

18. Structure of functional group of alcohol phenol and ether

19. Preparation of alcohols from alkenes
(i) by acid catalysed hydration
Alkenes react with water in the presence of acid as catalyst to form
alcohols. In case of unsymmetrical alkenes, the addition reaction takes
place in accordance with Markovnikov’s rule.

20. THF (tetrahydrofuran) is the solvent that is used to stabilize the dimer of BH3 which is a
flammable, toxic, and explosive gas.

21. Preparation of alcohols from carbonyl compounds

22. Preparation of alcohols from Grignard reagents

24. While studying organic chemistry, we have come across the term ‘phenol’ many times. Haven’t
you? So, what are phenols?
Preparation of Phenols
Phenols are the organic compounds that have a benzene ring bonded to a hydroxyl group. We also
know them by the name of carbolic acids. They are weak acids and generally form phenoxide
ions by losing one positive hydrogen ion (H+) from hydroxyl group.
In earlier days, people were able to synthesise phenol from coal tar. It was a very complex and
lengthy process. It had a lot of risks associated with it as well. Nowadays, with advancements in
technologies, however, certain new methods have come up for the preparation of phenols in
laboratories. In laboratories, chemists primarily synthesise and derive phenol from benzene
derivatives.
Joseph Lister discovered
that carbolic spray was very
effective in stopping wounds
from getting gangrene.

26. Preparation of Phenol
Chlorobenzene is fused with NaOH at 623K and 320 atmospheric pressure.
Phenol is obtained by acidification of sodium phenoxide so produced.
Benzene is sulphonated with oleum and benzene sulphonic acid so formed is
converted to sodium phenoxide on heating with molten sodium hydroxide.
Acidification of the sodium salt gives phenol.
A diazonium salt is formed by treating an aromatic primary amine with
nitrous acid (NaNO2 + HCl) at 273-278 K. Diazonium salts are hydrolysed
to phenols by warming with water or by treating with dilute acids.
Cumene (isopropylbenzene) is oxidised in the presence of air to cumene
hydroperoxide. It is converted to phenol and acetone by treating it with
dilute acid. Acetone, a by-product of this reaction, is also obtained in large
quantities by this method.

32. Phenols are weak acid in water. They undergo
deprotonation.

33. Saytzeff's Rule is also called Zaitsev's rule,
Saytzev's rule or Z-rule.

36. Based on the cleavage of O–H and C–O bonds, the reactions
of alcohols and phenols may be divided into two groups:

38. “The greater the pKa value, the weaker the acid. ”
Aspirin possesses analgesic, anti-inflammatory
and antipyretic properties.
H+

41. Trinitrophenol is a strong acid due to the presence of three electron
withdrawing –NO2 groups which facilitate the release of hydrogen
ion.