Home
JEE Chemistry
Alcohols and Ethers

Alcohols and Ethers

Alcohols and ethers are two important classes of organic compounds, each characterized by specific structures and properties. Let’s learn in detail about each of them.

1.0Alcohol and Ether Flow Chart

Here is a flow chart that provides an overview of alcohols and ethers. In this article, we will learn the difference between alcohols and ethers and the Classification of alcohol and ether.

Sources

              Alcohols

        Ethers

Fermentation of sugars (e.g., ethanol)

Dehydration of alcohols (symmetrical ethers)

Hydration of alkenes

Williamson synthesis (unsymmetrical ethers)

Reduction of aldehydes and ketones


                                                             Properties

            Alcohols

            Ethers

Hydroxyl group (-OH) attached to a carbon

Oxygen connected by single bonds to two alkyl or aryl groups

Soluble in water (especially lower alcohols)

Generally low solubility

The boiling point higher than the corresponding alkanes

Relatively low Boiling Points than alcohol.Excellent solvents due to stability

Note: With the same molecular formula alcohol and ethers are functional isomers.

                                                                 Reactions

                Alcohols

              Ethers

Esterification: React with carboxylic acids to form esters

Acidic Hydrolysis: Break down into alcohols in acid

Oxidation: Primary alcohols to aldehydes to acids, Secondary alcohols to ketones

Electrophilic Aromatic Substitution (for aromatic ethers): Introduction of substituents on the aromatic ring

Dehydration: Form alkenes


Uses

          Alcohols

            Ethers

Solvents, beverages, antiseptics, fuels (ethanol)

Solvents in industrial and laboratory settings, anesthetics (e.g., diethyl ether), starting materials in synthesis

2.0Alcohol

In chemistry, an alcohol definition involves any organic compound that includes a hydroxyl group (-OH) attached to a carbon atom.

Alcohols and phenols are two important classes of organic compounds, both containing a hydroxyl group (-OH) but differing in their structures, properties, and reactivity

Physical Properties of Alcohol

S.N.

General Property

Explanation

1.

Boiling and Melting Points

Alcohols have higher boiling and melting points than hydrocarbons of similar weight due to hydrogen bonding between their hydroxyl groups, requiring more energy to break.

2.

Solubility

Alcohols are more soluble in water than hydrocarbons due to hydrogen bonding with water molecules. Solubility decreases with longer carbon chains as hydrophobicity dominates.

3.

Density

Alcohols are generally less dense than water. For example, ethanol has a density of about 0.789 g/cm³ at 20°C.

4.

Volatility

Alcohols are more volatile than water but less volatile than many hydrocarbons of similar weight due to the hydroxyl group.

5.

Viscosity

Alcohols are less viscous than water but more so than hydrocarbons, with viscosity increasing as chain length and molecular weight rise.


6.

Miscibility

Alcohols are miscible with both organic solvents and water, especially those with shorter chains. Longer chain alcohols are more soluble in non-polar solvents but less in water.

Structure of Alcohol

Structure: Alcohols are organic compounds in which a hydroxyl group is bound to a saturated or unsaturated carbon atom. They can be classified based on the carbon to which the hydroxyl group is attached:

  • sp3 C-OH bonded compounds
  • sp2 C-OH bonded compounds
  1. sp3 C-OH bonded compounds

These are the most common type of alcohols, where the hydroxyl group is bonded to an sp3-hybridized carbon. This includes all aliphatic alcohols, where the carbon atom connected to the OH group is part of an alkyl chain.

Primary (1°): The carbon with the OH group is attached to only one other carbon.

Secondary (2°): The carbon with the OH group is attached to two other carbons.

Tertiary (3°): The carbon with the OH group is attached to three other carbons.

Alcohol

Allylic Alcohols- Allylic alcohols are organic compounds where the hydroxyl group (-OH) is attached to a sp3 hybridized carbon atom that is adjacent to a carbon-carbon double bond.

Vinyl Alcohol

Benzylic Alcohols- Definition: Benzylic alcohols are compounds in which the hydroxyl group (-OH) is bonded to a sp3 hybridized carbon atom that is directly adjacent to an aromatic ring.

Benzylic Alcohol

  1. sp2 C-OH bonded compounds-

Vinylic alcohols- Vinylic alcohols, also known as enols, are a specific type of alcohol where the hydroxyl group (-OH) is bonded to an sp2-hybridized carbon atom that is also part of a carbon-carbon double bond.

Vinyl Alcohol

Methods of Preparation of Alcohols

  1. From alkenes :

(a) By acidic hydration

By acidic hydration


(b) By hydroboration oxidation

hydroboration oxidation

(c) By oxymercuration demercuration

By oxymercuration demercuration

  1. By reaction of Grignard reagent with aldehydes and ketones :

By reaction of Grignard reagent

Methods of Preparation of Phenols

  1. From haloarenes: Phenols can be synthesized by the hydrolysis of haloarenes (aryl halides), particularly chlorobenzene, under high temperatures and pressure in the presence of a strong base such as sodium hydroxide (NaOH).

Preparation of Phenols from haloarenes

  1. From benzene sulphonic acid: Phenols can be prepared by the reaction of benzene sulphonic acid with sodium hydroxide, followed by acidification.

Preparation of Phenols from benzene sulphonic acid

Chemical Reactions of Alcohols

Reactions involving the cleavage of the O–H bond in alcohols are fundamental to many transformation processes in organic chemistry.

Reaction with Metals:

Alcohols can react with active metals such as sodium, potassium, or aluminum to produce alkoxides and hydrogen gas. This type of reaction demonstrates the acidic nature of the alcohol's hydroxyl group.

Chemical Reactions of Alcohol with Metals

Esterification reaction- The esterification reaction is a key organic transformation where alcohols and phenols react with acid chlorides, acid anhydrides, or carboxylic acids to form esters.

Alcohol's Esterification reaction

Chemical reactions of Phenol

  1. Nitration of Phenol

Nitration of Phenol

  1. Halogenation of Phenol

Halogenation of Phenol

3.0Ether

Ethers are a class of organic compounds characterized by an oxygen atom connected by single bonds to two alkyl or aryl groups. They have the general formula R-O-R', where R and R' can be either the same or different alkyl or aryl groups. Ethers are known for their relatively low reactivity compared to other functional groups like alcohols or amines. Let’s learn classification of Ether

4.0Classifications of Ether

Simple Ethers:

  • These are the most common types of ethers and are sometimes referred to as symmetrical ethers if both alkyl groups are the same (e.g., diethyl ether, .CH3CH2-O-CH2CH3)
  • If the alkyl groups are different, they are called unsymmetrical ethers (e.g., methyl ethyl ether, CH3-O-CH2CH3

Cyclic Ethers:

  • These ethers have their oxygen atom incorporated into a ring structure. The size of the ring can vary, and this class includes compounds like epoxides (three-membered rings), tetrahydrofurans (five-membered rings), and dioxanes (six-membered rings).
  • Epoxides, also known as oxiranes, are particularly important in synthetic chemistry due to their high reactivity.

Cyclic Ethers

Crown Ethers:

  • These are a special class of cyclic ethers known for their ability to complex with certain cations, particularly potassium and sodium ions. Crown ethers are named for their crown-like structure and the number of atoms in the ring.
  • An example is 18-crown-6, which has six ether groups and is particularly effective at binding potassium ions.

Crown Ethers

Aromatic Ethers:

  • Aromatic ethers have at least one aryl group attached to the oxygen. The most common example is anisole (CH3 -O-C6H5), where a methoxy group is attached to a benzene ring.
  • These ethers often show different reactivity patterns compared to aliphatic ethers due to the influence of the aromatic system.

Polyethers:

  • These are compounds containing multiple ether groups along a chain. Examples include polyethylene glycol (PEG), which is used in many applications ranging from industrial manufacturing to pharmaceuticals.

5.0Method of Preparation of Ethers

(1) Direct Synthesis from Alcohol

Ether's Direct Synthesis from Alcohol

(2) Williamson synthesis

This reaction involves the nucleophilic attack of an alkoxide ion on a primary alkyl halide, leading to the formation of an ether.

Williamson continuous etherification process

The Williamson continuous etherification process is a classic and widely used method for the synthesis of ethers, particularly useful for producing symmetrical and unsymmetrical ethers.

This process involves the reaction of an alkoxide ion with a primary alkyl halide via an SN2 mechanism, leading to the formation of an ether.

Williamson continuous etherification process

For Example 

Sodium phenoxide reacts with methyl iodide in a Williamson ether synthesis to produce anisole.

Example for Williamson continuous etherification process

6.0Chemical Reactions of Ether

  1. Reaction of ether with H+/H2O (Acidic hydrolysis)

The reaction of ethers with H⁺/H₂O, commonly known as acidic hydrolysis, is an important mechanism for breaking ether bonds, especially in symmetrical and unsymmetrical ethers. This reaction is more common for breaking down ethers into their constituent alcohols or converting them into other functional groups. 

Chemical Reaction of ether with H+/H2O

  1. Electrophilic substitution reactions

In aromatic ethers, the presence of an oxygen atom attached to the aromatic ring through an ether linkage increases the electron density on the ring, making it more reactive toward electrophiles.

Electrophilic substitution reactions


Frequently Asked Questions

Key reactions include esterification (to form esters), dehydration (to form alkenes), and oxidation (to form aldehydes, ketones, or acids).

Ethers are primarily used as solvents due to their stability and ability to dissolve a wide range of compounds. They are also used in the production of pharmaceuticals and as starting materials in chemical synthesis.

Ethers are relatively inert, but they can undergo reactions such as acidic hydrolysis (to form alcohols), and in the case of aromatic ethers, electrophilic aromatic substitution.

The general order of acidic nature is- Primary Alcohols (1°) > Secondary Alcohols (2°) > Tertiary Alcohols (3°)

Join ALLEN!

(Session 2025 - 26)


Choose class
Choose your goal
Preferred Mode
Choose State