Alcohols

• How are alcohols classified


  According to the environment of the OH group
• Describe the solubility of alcohols 


  The solubility decreases as the alcohol size increases because the hydrogen bonding in the OH group predominates, but as the chain increases it dominates
• Boiling point


  Increases as the molecules get larger
• Describe the natural way ethanol can be produced


  Through fermentation with yeast

  • Sugar and yeast at 40c
  • C6H12O6 ---> 2C25OH + 2CO2
• Describe how ethanol is produced synthetically

  The hydration of ethene

  • Ethene and steam with a catalyst
  • C2H4 + H2O ---> C2H5OH
• Is the fermentation of plant materials carbon neutral?


  Technically yes, because any CO2 released was originally absorbed by the plant from the air during it's lifetime
• Why is a continuous process (the hydration of ethene) better than a batch process (fermentation) for industry?


  Because batch processes limit how fast the reaction can happen
• How are alcohols oxidised?

  With acidified potassium dichromate
• What happens when a primary alcohol is oxidised?

  An aldehyde is formed and then further oxidised to a carboxylic acid
• What happens when a secondary alcohol is oxidised?

  A ketone is formed
• Why can a ketone not be oxidised by acidified potassium dichromate?


  Because a C-C bond would have to be broken which is much more difficult than breaking C-H bonds
• How can a ketone be differentiated from an aldehyde?

  By using Fehling's solution:

  • An aldehyde will turn the solution brick red
  • A ketone will not react
• What do alcohols react to make (elimination reaction)?


  Alkenes
• How many products will the elimination reactions of different alcohols have?

  Primary alcohols will have 1 product

  Secondary alcohols will produce 2 products - potential for 4 due to E/Z isomerism

  Tertiary alcohols - more
• What is the intermediate formed during an elimination reaction?


  A carbocation