Classification Alcohols, Phenols, and Ethers Formula

Alcohols: Organic compounds containing hydroxyl (-OH) group as a functional group bonded to a saturated carbon atom.

Example: CH₃OH (Methanol)

Phenols: Compounds in which the hydroxyl group is directly attached to an aromatic ring.

Example:  C₆H₅OH (Phenol)

Ethers: Compounds that contain an oxygen atom bonded to two alkyl or aryl groups.

Example: CH₃OCH₃ ​ (Dimethyl ether)

Classification of Alcohols

Primary (1°): The carbon atom bonded to the -OH group is bonded to only one other carbon atom.

Example: Ethanol CH₃CH₂OH

Secondary (2°): The carbon atom bonded to the -OH group is bonded to two other carbon atoms.

Example: Isopropanol CH₃CHOHCH₃ ​

Tertiary (3°): The carbon atom bonded to the -OH group is bonded to three other carbon atoms.

Example: Tert-butanol (CH₃)₃COH 

Phenols: Typically not classified in the same way as alcohols since the -OH is always attached to an aromatic ring.

Ethers: Symmetrical (Simple) Ethers: Same alkyl groups on both sides of the oxygen.

Example: Dimethyl ether CH₃OCH₃ ​ 

Unsymmetrical (Mixed) Ethers: Different alkyl or aryl groups on either side of the oxygen.

Example: Ethyl methyl ether CH₃OCH₂CH₃ ​ 

Nomenclature 

Alcohols: Named with the suffix “-ol” added to the name of the parent alkane.

Example: CH₃CH₂OH is Ethanol.

Phenols: The word “phenol” itself is used if there are no substituents. If substituents are present, their positions are indicated using numbers.

Example: C₆H₄(OH)(CH₃) can be named as m-cresol where the methyl group is meta to the hydroxyl group.

Ethers: In the common naming system, name the two alkyl or aryl groups alphabetically and add “ether”.

Example: CH₃OCH₂CH₃ ​ is ethyl methyl ether. In the IUPAC system, it’s named as alkoxyalkanes. For example, the above can be named as methoxyethane.

Preparation of Alcohols

From Alkenes: 

Acid-catalyzed hydration.

CH₂=CH₂ ​ + H₂O → CH₃CH₂OH (in the presence of acid)

From Grignard Reagents:

CH₃MgBr + H₂O→ CH₄ ​ + Mg(OH)Br 

Reduction of Carbonyl Compounds: Using reducing agents like LiAlH₄ or NaBH₄.

RCHO + 2[H] → RCH₂OH

Also Check – Acids and Bases Formula: Types of Reaction

Preparation of Phenols 

From Halobenzenes: Using aqueous NaOH at high temperatures (called the Dow process).

C₆H₅Cl + NaOH → C₆H₅OH + NaCl 

From Benzene Sulphonic Acid: Through fusion with NaOH.

C₆H₅SO₃H + 3NaOH → C₆H₅OH + 3NaHSO₃ ​

Also Check – PH of Weak Acid Formula

Physical and Chemical Properties of Alcohols and Phenols 

Boiling Point: 

Alcohols and phenols have higher boiling points than their corresponding hydrocarbons due to hydrogen bonding.

Acidity:

Phenols are more acidic than alcohols due to the delocalization of the negative charge over the aromatic ring in the phenoxide ion.

Reaction with Halides: 

Alcohols react with halide ions in the presence of acids to form haloalkanes.

ROH + HX → RX + H₂O 

This is termed as the Lucas Test when using anhydrous ZnCl₂ with alcohols to distinguish between primary, secondary, and tertiary alcohols.

Ester Formation: 

Alcohols react with carboxylic acids to form esters in the presence of an acid catalyst.

RCOOH + R′OH → RCOOR ′ + H₂O 

Oxidation: 

While secondary alcohols can be oxidized to ketones, primary alcohols can be converted to aldehydes and then to carboxylic acids. Alcohols in the tertiary stage do not simply oxidize.

Reimer-Tiemann Reaction:

 Phenol, when treated with chloroform in the presence of aqueous NaOH, results in the formation of salicylaldehyde. This reaction involves the formation of dichlorocarbene.

C₆H₅OH + CHCl₃ ​ + 4NaOH → C₆H₄CHO(OH) + 3NaCl + 3H₂O 

Williamson Ether Synthesis: 

An alcohol is first converted into a sodium alkoxide, which then reacts with an alkyl halide to form an ether.

RONa + R ′ X → ROR ′ +NaX