Chapter 22: Alcohols, Ethers, Phenols, and Thiols

Functional Groups
  • Class of compounds defined by specific functional groups.
  • These groups create new substances through chemical reactions.
Classification of Alcohols
  • Types: Alcohols are classified as:
    • Primary (1°): Carbon bonded to one other carbon (–OH attached to 1° carbon).
    • Secondary (2°): Carbon bonded to two other carbons (–OH attached to 2° carbon).
    • Tertiary (3°): Carbon bonded to three other carbons (–OH attached to 3° carbon).
Naming Alcohols
  1. Longest Chain: Identify the longest chain containing the –OH group.
  2. Numbering: Number carbons so that the –OH has the lowest possible number.
  3. Parent Name: Replace the final –e of alkane with –ol.
    • Example: CH3CH2CH2CH2OH = 1-butanol.
Physical Properties of Alcohols
  • Solubility: Alcohols with up to three carbons are infinitely soluble in water due to the –OH group.
  • Boiling Points: Higher boiling points than alkanes; normal alcohols show increasing boiling points with more carbons.
  • Hydrogen Bonding: Alcohols engage in hydrogen bonding, affecting solubility and boiling points.
Chemical Properties of Alcohols
  • Acidic and Basic Properties: Can act as acids (giving up protons) and bases (accepting protons).
  • Oxidation: Alcohols can be oxidized to aldehydes, ketones, or carboxylic acids.
  • Dehydration: Removal of water leads to formation of alkenes.
  • Esterification: Reaction between alcohols and carboxylic acids to form esters.
Common Alcohols and Their Uses
  • Methanol (CH3OH): Used in making formaldehyde, industrial solvents, and as a fuel.
  • Ethanol (C2H5OH): Produced by fermentation; used in beverages, solvents, and as a chemical intermediate.
  • Isopropanol (2-Propanol): Used as a solvent and in rubbing alcohol formulations.
  • Ethylene Glycol (1,2-Ethanediol): Used in antifreeze and as a solvent.
  • Glycerol (1,2,3-Propanetriol): Used in cosmetics and food, known for its moistening properties.
Phenols
  • Definition: Compounds with a hydroxy group attached to an aromatic ring.
  • Properties: Colorless, poisonous, more acidic than alcohols.
  • Production: Often derived from coal tar or through synthetic processes.
Ethers
  • General Formula: ROR'.
  • Properties: Less polar than alcohols but excellent solvents for organic compounds, can form peroxides that are explosive.
  • Preparation: Via Williamson synthesis or other methods involving alkyl halides and alkoxides.
Thiols
  • Definition: Compounds containing the –SH group (mercaptans).
  • Properties: Known for foul odors and can oxidize to form disulfides (R-S-S-R).
Chemical Reactions Summary
  • Oxidizing agents: Common agents include KMnO4 and K2Cr2O7.
  • Reactivity: 1° alcohols react more readily than 2° or 3° alcohols in various reactions such as with sodium or potassium.
Tables Reference
  • Boiling Points: Comparison of boiling points for alkanes, alcohols, and ethers demonstrates the significant effect of hydrogen bonding in alcohols.
  • Classifications: Naming and properties of common alcohols highlight differences between primary, secondary, and tertiary structures with respect to their physical and chemical properties.