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Overview of Alcohols, Phenols, and Ethers

Aug 4, 2024

Alcohols, Phenols, and Ethers Lecture Notes

Introduction

  • Topic: Alcohols, Phenols, and Ethers
  • Previous Session: Halogen Derivatives (reactions, chemical properties)
  • Today's Objective: Cover functional groups - Alcohols, Phenols, and Ethers

General Formulas

Alcohols and Phenols

  • Alcohols: Hydroxyl group (-OH) attached to alkyl (R-OH)
  • Phenols: Hydroxyl group attached to an aromatic ring (Ar-OH)
  • Ethers: Oxygen atom connected to two alkyl or aryl groups (R-O-R)

Nomenclature

Alcohols

  1. Methanol: CH3OH (Common Name: Methyl Alcohol, IUPAC: Methanol)
  2. Ethanol: CH3CH2OH (Common Name: Ethyl Alcohol, IUPAC: Ethanol)
  3. Isopropyl Alcohol: CH3CHOHCH3 (Common Name: Isopropyl Alcohol, IUPAC: Propan-2-ol)
  4. Tertiary Butyl Alcohol: (CH3)3COH (Common Name: Tertiary Butyl Alcohol, IUPAC: 2-Methylpropan-2-ol)

Phenols

  • Phenol: Hydroxyl group attached to benzene (Common Name and IUPAC: Phenol)

Preparation Methods

Alcohols

  1. From Alkyl Halides: Nucleophilic substitution reaction (R-X with moist Ag2O)
  2. From Alkenes: Acid-catalyzed hydration (Alkene + H2SO4)
  3. Hydroboration-Oxidation: (Alkene + BH3/THF + H2O2)
  4. Reduction of Carbonyl Compounds: Using H2/Ni, LiAlH4 (Aldehydes to primary alcohols, Ketones to secondary alcohols)
  5. Grignard Reagent Addition: (RMgX with formaldehyde to produce primary alcohol, with other aldehydes to secondary alcohols)

Phenols

  1. From Chlorobenzene (Dow Process): Chlorobenzene + NaOH (fused) -> Sodium phenoxide + HCl -> Phenol
  2. From Cumene: Cumene + O2 -> Cumene hydroperoxide + H3O+ -> Phenol + Acetone
  3. From Benzene Sulfonic Acid: Benzene sulfonic acid + NaOH -> Sodium phenoxide + H3O+ -> Phenol
  4. From Aniline: Aniline + NaNO2 + HCl -> Benzene diazonium chloride + CuCl -> Phenol

Reactions of Alcohols

Dehydration Reactions

  1. Primary Alcohols: Produce alkenes when heated with concentrated H2SO4 (443K)
  2. Secondary Alcohols: Heated with concentrated H2SO4 (373K)
  3. Tertiary Alcohols: Heated with concentrated H2SO4 (363K)

Oxidation Reactions

  1. Primary Alcohols: To Aldehydes and further to Carboxylic acids using KMnO4/K2Cr2O7
  2. Secondary Alcohols: To Ketones using KMnO4/K2Cr2O7
  3. Tertiary Alcohols: Generally resistant to oxidation

Reactions of Phenols

Halogenation

  1. Bromination: Phenol + Br2 -> 2,4,6-tribromophenol (white precipitate)

Nitration

  1. Dilute HNO3: Phenol + HNO3 -> ortho- and para-nitrophenol
  2. Concentrated HNO3: Phenol + HNO3 -> 2,4,6-trinitrophenol (picric acid)

Sulfonation

  1. Dilute H2SO4: Phenol + H2SO4 -> ortho- and para-phenol sulfonic acid

Riemer-Tiemann Reaction

  • Formation of Salicylaldehyde: Phenol + CHCl3 + NaOH -> Salicylaldehyde

Kolbe's Reaction

  • Formation of Salicylic Acid: Phenol + CO2 + NaOH -> Salicylic Acid

Reactions of Ethers

Preparation Methods

  1. Dehydration of Alcohols: (ROH + ROH) -> Ether + H2O
  2. Williamson Synthesis: (RX + R'O-Na+) -> Ether + NaX

Reactions Involving Cleavage

  1. With HX (Acidic cleavage): Ether + HX -> Alkyl halide + Alcohol
  2. With PCl5: Ether + PCl5 -> Alkyl chloride + POCl3

Electrophilic Substitution Reactions

  1. Halogenation: Anisole + Br2 -> 2,4,6-tribromoanisole
  2. Nitration: Anisole + HNO3 -> ortho- and para-nitroanisole
  3. Friedel-Crafts Alkylation/Acylation: Anisole + CH3Cl -> ortho- and para-methoxy toluene (with AlCl3)

Applications

Alcohols

  1. Methanol: Solvent, antifreeze
  2. Ethanol: Solvent, antiseptic
  3. Phenols: Antiseptics, resins
  4. Ethers: Solvents in Grignard reactions, anesthetics

This summary provides an overview of the key points from the lecture on Alcohols, Phenols, and Ethers, including their general formulas, nomenclature, preparation methods, reactions, and applications.

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