Lecture Notes: Chemistry - Alcohols, Phenols, and Ethers

Introduction

• Focus on organic chemistry, specifically on alcohols, phenols, and ethers.
• Covers preparation, properties, reactions, and uses.
• Identification of primary, secondary, and tertiary alcohols.

Alcohols

General Formula

• Alcohols are organic compounds with the functional group R-OH.
• Hydroxy derivatives of hydrocarbons.

Structure

• Bent shape due to lone pair-bond pair repulsion.
• Bond angles in alcohols are less than tetrahedral bond angles.

Types of Alcohols

• Monohydric: Single OH group.
• Dihydric: Glycol (e.g., ethylene glycol).
• Trihydric: Glycerol (e.g., 1,2,3-propanetriol).

Classification

• Based on the carbon atom bonded to -OH:
  • Primary (1°)
  • Secondary (2°)
  • Tertiary (3°)

Preparation

• Reactants and reagents yield alcohols.
• Common methods involve nucleophilic substitution with halides.

Reactions

• Dehydration: Alcohols lose water to form alkenes.
• Oxidation:
  • Primary alcohols to aldehydes, then to carboxylic acids.
  • Secondary alcohols to ketones.
  • Tertiary alcohols generally do not oxidize.
• Reaction with Carboxylic Acids: Forms esters.

Phenols

Structure

• Aromatic compounds with hydroxyl groups attached directly to the aromatic ring.
• Highly acidic in nature.

Reactions

• Electrophilic Substitution: Predominantly occurs at ortho and para positions.
• Halogenation, Nitration, Sulfonation: Phenols undergo these reactions due to activated aromatic ring.

Properties

• Phenols are more acidic than alcohols due to stabilization of phenoxide ion.

Ethers

General Formula and Classification

• R-O-R’ where R and R’ can be alkyl or aryl groups.
• Symmetrical and asymmetrical ethers.

Preparation

• Williamson Ether Synthesis: Reaction of an alkoxide ion with a primary alkyl halide.

Reactions

• Cleavage by HX: Ethers react with hydrogen halides to form alcohol and alkyl halide.

Additional Concepts

Mechanisms

• Detailed mechanisms of alcohol dehydration and phenol substitution reactions.

Acidic and Basic Nature

• Phenols are more acidic than alcohols due to resonance stabilization.
• Acidic strength influenced by electron withdrawing/donating groups.

Uses and Applications

• Alcohols, phenols, and ethers are used in various industrial applications as solvents, antiseptics, and intermediates in synthesis.

Conclusion

• Summary of key concepts and reactions discussed.
• Encouragement to subscribe and join future sessions.