Alcohols

• Functional group of an alcohol

  Hydroxyl group -OH
• General formula of an alcohol

  CnH2n+1OH
• Naming alcohols


  One prefix (Hydroxyl-) and one suffix (-ol)
• Alcohols


  • Have hydrogen bonding due to the electronegativity difference in the OH bond
• Alcohols' melting point and boiling point

  Higher than other hydrocarbons of similar C chain lengths, because they have hydrogen bonding (strongest type of intermolecular force) which is stronger than London forces
• Solubility of alcohols in water

  Soluble when short chain - OH hydrogen bonds to hydrogen bond in water, Insoluble when long chain - non-polarity of C-H bond takes precedence
• Primary alcohol


  C bonded to OH is only bonded to one other C atom
• Secondary alcohol


  C bonded to OH is bonded to two other C atoms
• Tertiary alcohol


  C bonded to OH is bonded to three other C atoms
• Combustion of ethanol


  C2H5OH (l) + 3O2 (g) → 2CO2 (g) + 3H2O (l)
• Partial oxidation of a primary alcohol

  Forms an aldehyde
• Conditions for partial oxidation of a primary alcohol

  Dilute sulphuric acid, potassium dichromate (VI), distill product as it's produced, gentle heating
• Equation for partial oxidation of ethanol

  CH3CH2OH (l) + [O] → CH3CHO (g) + H2O (l)
• Full oxidation of a primary alcohol


  Forms a carboxylic acid
• Conditions for full oxidation of a primary alcohol

  Concentrated sulphuric acid, potassium dichromate (VI), reflux, strong heating
• Equation for full oxidation of ethanol

  CH3CH2OH (l) + 2[O] → CH3COOH (g) + H2O (l)
• Oxidation of a secondary alcohol


  Forms a ketone
• Conditions for oxidation of a secondary alcohol

  Concentrated sulphuric acid, potassium dichromate (VI), strong heating
• Equation for oxidation of propan-2-ol

  CH3CH(OH)CH3 (l) + [O] → CH3COCH3 (g) + H2O (l)
• It is not possible to oxidise tertiary alcohols
• Dehydration reaction


  A reaction where water is lost to form an organic compound
• Products of dehydration reaction of alcohol

  Alkene and water
• Conditions required for dehydration of alcohol


  Concentrated sulfuric acid or concentrated phosphoric acid and 170°C
• Products of halide substitution reaction with alcohol

  Haloalkane and water
• Form of halide used in halide substitution reaction


  In the form of hydrogen halide, e.g HBr
• How hydrogen halide is made in situ

  A salt is reacted with acid to form the hydrogen halide, e.g. sodium bromide reacts with sulfuric acid to form HBr. When iodine is reacted, phosphoric acid is used as sulfuric acid oxidises iodide ions into iodine.