7.2 Reactions of alkenes and alcohols

• Why are alkenes considered unsaturated?


  They have at least one double bond
• What are the first four alkenes?


  Ethene, propene, butene, pentene
• How do alkenes react with oxygen?


  They undergo combustion reactions
• What is a characteristic of alkenes when burned in air?


  They tend to burn with smoky flames
• What is produced during incomplete combustion of alkenes?


  Carbon or carbon monoxide
• What happens to the double bond in alkenes during reactions with hydrogen, water, and halogens?


  The double bond becomes a single bond
• What are the reactions of alkenes with hydrogen, water, and halogens?


  • Double bond breaks to form a single bond
  • Added compound splits into two groups
  • Each group attaches to different carbons
• What is the functional group of alcohols?


  OH
• What are the first four alcohols?


  Methanol, ethanol, propanol, butanol
• What are the reactions of alcohols?


  • Burn in air to produce carbon dioxide and water
  • Dissolve in water to form neutral solutions
  • React with sodium to produce hydrogen and salt
  • React with oxidising agents to form carboxylic acids
• What are the uses of methanol, ethanol, propanol, and butanol?


  • Methanol: chemical feedstock, anti-freeze, biodiesel
  • Ethanol: alcoholic drinks, solvent, fuel
  • All four: can be used as fuels
• How is ethanol produced?


  By fermentation of sugar with yeast
• What are the conditions for producing ethanol?


  About 35°C, anaerobic, yeast enzyme catalyst
• What is the equation for the fermentation of sugar?


  Sugar → ethanol + carbon dioxide
• What is the functional group of carboxylic acids?


  COOH
• What is the first four members of carboxylic acids?


  Methanoic, ethanoic, propanoic, butanoic acid
• What are the reactions of carboxylic acids?


  • Dissolve in water to produce acidic solutions
  • React with metal carbonates to produce carbon dioxide, salt, and water
  • React with alcohols to produce esters
  • Do not ionise completely, making them weak acids
• Why do carboxylic acids have a higher pH than strong acids?


  They do not release many H+ ions
• How do carboxylic acids react with alcohols?


  To produce esters in the presence of acid catalyst
• What happens when carboxylic acids react with metal carbonates?


  They produce carbon dioxide, salt, and water
• What is produced when carboxylic acids dissolve in water?


  Acidic solutions with pH less than 7