organ 3

• Alcohols


  Hydrocarbons in which one or more hydrogen atoms are substituted with the OH (hydroxyl) group
• Alcohols

  • The -O-H and C-O bonds are polarized, leading to dipole-dipole interactions between molecules
• Hydrogen bonding

  Intermolecular interaction between the -O-H functionality of alcohol molecules
• Alcohols

  • Ethane
  • Methanol
  • Dimethyl ether
  • Propane
• Alcohols

  Weak proton donors (acids) and proton acceptors (bases), but do not ionise to give OH- ions or readily yield H+ ions
• Alcohols

  • Hydrogen bonding with water adds to water solubility
  • Solubility in water increases as ratio of polar (smaller alkyl groups) to non-polar structure increases
• Alcohols are found in many drugs and can be susceptible to fast metabolism in vivo due to their reactivity
• Dehydration (water elimination) reactions of alcohols

  1. Major

  2. Minor

  3. Carbocation intermediate
• Phosphoric acid catalysed dehydration of propan-2-ol

  Mechanism
• Oxidation/reduction (Redox) reactions of alcohols

  • Aldehyde
  • Carboxylic acid
  • Ketone
  • 1° alcohol
  • 2° alcohol
• Oxidation reagents for alcohols include aqueous KMnO4 (acidic or basic), aqueous K2Cr2O7 (acidic)
• Phenols (phenyl alcohols)

  Weak acids that can neutralise basic reagents
• Phenol will turn blue litmus paper red, while cyclohexanol's dissociation is negligible and doesn't affect litmus paper
• Substituents bearing a lone pair of electrons (such as a hydroxy group)

  • Can delocalise their electron density onto an adjacent aromatic ring
• Ethers


  Compounds in whose molecules two organic groups are joined to the same oxygen atom
• Preparation of symmetrical ethers


  Dehydration reactions of primary alcohols, thought to proceed via a sulfuric acid ester (sulfate)
• Preparation of asymmetrical ethers

  Williamson ether synthesis using an alkoxide ion and an alkyl halide
• Thiols and thiophenols


  • Similar to alcohols and phenols but less soluble due to weaker hydrogen bonding ability, stronger acids, better nucleophiles, and more easily oxidised
• Thiols and thiophenols are seen in many drugs and have applications such as in the treatment of heavy metal poisoning and schizophrenia