CBSE Class 12 Chemistry Notes Chapter 11 Alcohols, Phenols and Ether

Alcohols, Phenols and Ethers belong to the class of organic compounds formed by substituting one or more atoms in a hydrocarbon with another group of atoms. 

• Alcohol is a type of compound that consists of at least one hydroxyl (−OH) functional group bound with a carbon atom.
• Phenol, also known as benzenol, is a type of aromatic compound where the phenyl group is bonded with a hydroxyl group.
• Ether group consists of bond formation between ether and two alkyl or aryl groups.
• These are naturally organic molecules that are derivatives of alkanes or alkyl groups.
• Alcohols, Phenols and Ethers have a wide range of applications, which include the preparation of antiseptics, detergents and fragrances.
• Methanol and ethanol are the most common examples of alcohol, and bakelite is an important example of phenol.
• Ethers are mostly used in solvents and anesthetics. 

According to the CBSE Syllabus 2023-24, the chapter on Alcohols, Phenols and Ethers has been renumbered as NCERT Class 12 Chemistry Chapter 7. Alcohols, Phenols and Ethers Notes are given in the article below for preparation for the CBSE Class 12 Chemistry Examination.The chapter helps an individual score six marks in the board exam.

Read More:

---

Alcohols, Phenols and Ether Notes

Nomenclature of Alcohols, Phenols and Ethers

The nomenclature of alcohols, phenols and ethers consists of the functional group OH. 

Nomenclature of Alcohols

In IUPAC nomenclature, the name of alcohol is obtained by replacing the last ‘e’ with the corresponding ‘-ol’.

• The nomenclature of alcohols is classified into monohydric alcohol, dihydric alcohol, and trihydric alcohol. 
• Monohydric alcohol consists of one OH group with the formula C_nH_2n+1OH (n=1,2,3, etc).
• Primary, secondary and tertiary alcohol are three types of monohydric alcohol.
• Dihydric alcohol consists of two OH groups with the formula (CH₂)_n(OH)₂ (n=1,2,3 etc.)
• Trihydric alcohol consists of three OH groups with the formula (CH₂)_n(OH)₃ (n=3,4,5 etc.).

Nomenclature of Alcohols

Nomenclature of Phenol

The IUPAC and common name of the compound consists of the substitution of phenol with the derivative of phenols. 

• The substitution is done by the addition of prefixes like Ortho (o-) for 1:2, meta (m-) for 1,3, and para (p-) for 1,4.
• Nomenclature of phenol is given names of hydroxyl derivatives of the phenol group.

Nomenclature of Phenols

Nomenclature of Ether

The nomenclature of ether is subdivided into the IUPAC system and common name.

• In the IUPAC system, ethers are given the name alkoxy alkanes.
• The common system of ether involves naming the two alkyl or aryl groups linked to the oxygen atom. 

Nomenclature of Ether

Classification of Alcohols, Phenols and Ethers

Classification of alcohols, phenols and ethers is based on various factors, which are as follows:

Classification of Alcohols

• Classification of alcohol is done on the basis of OH group and the number of carbon atoms.
• On the basis of the OH group, alcohols are classified into monohydric, dihydric and trihydric alcohols.
• Alcohols are classified into primary, secondary, and tertiary alcohols on the basis of the number of carbon atoms.
• Primary alcohol consists of only one carbon atom attached to the OH group.
• Secondary alcohol consists of two carbon atoms attached to the OH group.
• Tertiary alcohol consists of three carbon atoms attached to the OH group.

Classification of Alcohols

Classification of Phenol

• Classification of phenol is based on the number of hydroxyl groups attached to the organic compound.

• They are classified into monohydric phenols, dihydric phenols, and trihydric phenols.
• Monohydric phenol consists of one -OH group.
• Dihydric Phenol consists of two -OH groups.
• Trihydric phenol consists of three -OH groups.

Classification of Ether

• Classification of ether is based on the alkyl or aryl groups attached to the oxygen atom.
• They are classified into symmetrical ether and unsymmetrical ether.
• Symmetrical ether involves the addition of the same alkyl or the aryl group attached to either side of the oxygen atoms.
• Unsymmetrical Ether involves the addition of the different aryl or alkyl groups attached to either side of the oxygen atoms.

Physical Properties of Alcohols, Phenols and Ethers

The physical properties of alcohols, phenols and ether are as follows:

Physical Properties of Alcohols

• The boiling point of alcohol is higher in comparison to other hydrocarbons.
• The compound is liquid at room temperature.
• Acidic nature of alcohol is explained with the polarity of the -OH bond.
• The electron density of the oxygen atom increases when alcohol reacts with alkoxide.

Physical Properties of Phenols

• The boiling point of phenols increases with an increase in the number of carbon atoms.
• They are highly soluble in water.
• The electron density decreases when phenol reacts with active metals to form phenoxides.
• They are highly acidic in nature in comparison to alcohol.

Physical Properties of Ether

• The dipole moment of ether is quite small as the bond angle is not 180 degrees.
• It has low boiling points in comparison to alcohol.
• The compound is miscible in water.

Chemical Properties of Alcohols, Phenols and Ethers

The chemical properties of alcohols, phenols and ethers are as follows:

Chemical Properties of Alcohols

• Dehydration of Alcohol: In the dehydration process, alcohol is exposed to an acidic medium to form alkene.

Dehydration of Alcohol

• Esterification: The process involves the reaction of alcohol with carboxylic acid to form a sweet-smelling compound called an ester.

Esterification

• Reaction with metal: In this process, alcohol reacts with metals like sodium and potassium to form the corresponding alkoxide.

Reaction with metal

• Oxidation Reaction: In this, alcohol is oxidised in the presence of an oxidising agent to produce compounds like ketones and aldehydes.

Oxidation Reaction

Chemical Properties of Phenols

• Halogenation: In this process, phenol is treated with bromine in the presence of a solvent of low polarity like CHCl₃ to form a compound like monobromophenol.
• Electrophilic Substitution Reaction: It involves oxidation and poly-substitution of phenols in mild conditions.
• Hydrogenation: The hydrogenation of phenols involves the formation of a compound named cyclohexanone.
• Ester: The formation of ester involves a reaction between chlorides and anhydrides react with ArOH in the presence of a strong base.

Chemical Properties of Ether

• Electrophilic Substitution Reaction: The reaction involves the activation of aromatic ethers due to the presence of an alkoxy group.

Electrophilic Substitution Reaction

• Halogenation: The alkyl compound undergoes a substitution reaction with halides to form halogenated ether in the absence of sunlight.

Halogenation

Preparation of Alcohols, Phenols and Ethers

There are different ways for preparation of alcohols, phenols and ethers, which are as follows:

Preparation of Alcohols

• From Haloalkanes: In this process, haloalkane is heated with aqueous alkali, or moist silver oxide, which forms monohydric alcohol.

Preparation of Alcohols from Haloalkanes

• By Fermentation: In the process of fermentation, large organic molecules like carbohydrates are treated with suitable enzymes to produce alcohol.

Preparation of Alcohols by Fermentation

• Grignard Reagents: It involves the addition of Grignard reagents like alkyl magnesium halide with aldehydes and ketones to form the required alcohol.

Grignard Reagents

• Hydrolysis: In the process of hydrolysis, alkenes are treated with concentrated sulfuric acid to produce secondary and tertiary alcohol.

Hydrolysis

• Reduction of Carbonyl Compounds: It involves the reduction of aldehydes and ketones with sodium borohydride or lithium aluminium hydride to produce primary and secondary alcohol, respectively.

Preparation of Phenol

• Cumene Process: Cumene is produced by undergoing Friedel Crafts alkylation of benzene with propylene.

Cumene Process

• From Haloarenes: The process involves the substitution of chloro compound with the benzene ring, which is fused with sodium hydroxide.

Preparation of Phenol from Haloarenes

• From Benzene Sulphonic Acid: The process involves reaction of benzene with oleum to form Benzene Sulphuric acid which is later treated with molten sodium hydroxide to form sodium phenoxide.

Preparation of Phenol from Benzene Sulphonic Acid

• From Diazonium salts: In this process of preparation of phenol, diazonium salts are hydrolyzed to phenols after introduction to warm water. 

Preparation of Phenol from Diazonium salts

Preparation of Ether

• Dehydration of Alcohol: In this process, alcohol is dehydrated in the presence of protic acids like sulphuric acid and phosphoric acid to produce alkenes and ethers.

Dehydration of Alcohol

• Williamson Synthesis: Williamson synthesis is used for the preparation of symmetrical and asymmetrical ether by reaction of an alkyl halide with sodium alkoxide.

Williamson Synthesis

Uses of Alcohols, Phenols and Ethers

The uses of alcohols, phenols and ethers are as follows:

Uses of Alcohol

• Alcohol is considered a highly efficient fuel. 
• The compound is used in cosmetics because it is rubbing alcohol.
• It is used in the preparation of polyesters, explosives, resins, synthetic waxes, and explosives.

Methanol

• Methanol is used as an industrial solvent.
• It is used as an important ingredient in lotions and moisturizers, which are used after the skin is exposed to the sun.
• The compound is used in pain relief gels and balms to provide pain-relieving effects.
• Methanol is used to alleviate nasal and throat congestion associated with colds.

Ethanol

• Ethanol is most commonly used in cosmetics and beauty products.
• It is considered a good motor fuel as it has a high octane ratio.
• The compound is used as an ingredient in cleaning products since it is capable of knocking out living forms.

Uses of Phenol

• Phenol is used as an antiseptic and precursor in drugs.
• The compound is also used in the synthesis of plastics and the production of nylon.
• It is used in the preservation of vaccines.
• Phenol is used in hair colour and sunscreen.

Uses of Ether

• Ether is considered an important ingredient in anaesthesia, which is used in surgeries.
• It is used as a common solvent for oils, gums, resins, etc.
• Compounds, such as dimethyl ether, act as refrigerants and solvents at low temperatures.

There are Some important List Of Top Chemistry Questions On Alcohols, Phenols And Ethers Asked In CBSE CLASS XII