Topic 5 Alcohols

• You can make alkenes by eliminating water from alcohols in a dehydration reaction
• What are the conditions for a dehydration reaction? [2]

  Ethanol is heated with a concentrated sulphuric acid catalyst. The product is usually a mixture with water, acid and reactant in it so the alkene has to be separated out
• What are the conditions for the hydration of alkenes? [2]

  The standard industrial method for making alcohol is to hydrate an alkene using steam in the presence of an acid catalyst
• Ethanol can be made from the fermentation of glucose. Describe how [4]

  Fermentation is carried out by yeast in anaerobic conditions.

  Yeast produces an enzyme which converts sugars into ethanol and CO2

  Has an optimum temp of 30-40 degrees

  once formed ethanol separated from the rest of the mixture by fractional distilation
• Fermentation is cheap and renewable
• Biofuels are renewable so more sustainable than fossil fuels

  bio fuels are carbon neutral

  petrol car engines would have to be modified to use bio fuels

  land used to grow bio fuel can’t be used to grow food so sacrifice
• A biofuel is a fuel thats made from biological material that recently died
• What is the oxidation of alcohols? [4]

  Oxidising agent is acidified potassium dichromate. Orange to green

  primary alcohol are oxidised to aldehyde then Carboxylic acid

  secondary alcohols are oxidised to ketones

  tertiary alcohols don’t oxidise
• oxidising agents: Fehling’s solution and Benedict’s solution are both deep blue Cu2+ complexes, which reduce to brick red Cu2O when warmed with an aldehyde, but stay blue with a ketone
• Oxidising agents: Tollens reagent is [Ag(NH3)2]+ it is reduced to silver when warmed with an aldehyde but not with a ketone. the silver coat the inside of the apparatus to form a silver mirror