6.4.5 alcohols

• Alcohols:

  • functional group (what every alcohol contains): -OH
  • suffix: -anol
  • general formula: CnH2n+1OH

  e.g. C12H25OH
• Properties of alcohols:

  • liquids
  • soluble in water
  • good solvents
  • longer hydrocarbon chains = viscous (thicker) liquids
  • C-C and C-H bonds are unreactive
  • C-O and O-H bonds do not react with other things

  All alcohol properties are due to the -OH functional group
• Alcohols burn easily and produce a blue flame
• Combustion of alcohols:

  • C4H9OH + 6O2 -> 4CO2 + 5H2O
• Ethanol:

  • volatile liquid - evaporates quickly at room temp
  • colourless
  • burns readily in air with blue flame
  • good solvent
• Uses of ethanol:

  • biofuels
  • solvents
  • drinks
  • feedstock for synthesis (used to make something more useful)
  • cleaner
• Primary alcohols oxidises into an aldehyde when an oxidising agent e.g. acidified potassium dichromate VI.

  The aldehyde formed can be further oxidised into a carboxylic acid
• Pentanol -(oxidising agent)-> pentanal -(oxidising agent)-> pentanoid acid
• -anol + -anal + -anoic acid
• Alcohols are used as fuels, solvents, cleaning agents, antiseptics, paints, varnishes, perfumes, flavours, medicines.