other reactions of alcohols

• Esterification

  chemical reaction to make esters (-COOR)

  • used to manufacture food due to the pleasant, fruity smell
• Esterification of alcohols

  common way to make an ester

  →reacting an alcohol with a carboxylic acid in presence of an acid catalyst

  →during the reaction the O-H + C-O in carboxylic acid are broken + new bonds between H and O-H make water

  e.g. ethanoic acid + methanol ⇌ methyl ethanoate + water
• Esterification of alcohols 2

  • in a laboratory, only a few cubic centimetres of liquid alcohol + carboxylic acid are mixed in a test tube

  → a few drops of concentrated sulphuric acid are added to act as a catalyst + also 80 degrees water bath to increase rate of reaction

  smell is noticeable after a few minutes

  • only small molecules esters are soluble in water, many are visible as an oily layer floating on top of he reaction mixture

  → when working on a large scale, you can continue to distil to collect ester product
• Dehydration

  type of elimination reaction

  • when alcohols are heated with a strong acid (like concentrated H2SO4), water is eliminated to form an alkene)

  →happens when -OH group from one carbon atom + an H atom on an adjacent carbon atom lost to form H2O molecule

  pi bond form between 2 adjacent carbon atoms

  on laboratory scale, alcohol is heated under reflux with concentrated H2SO4 or concentrated H3PO4 (act as a catalyst) for about 40 minutes
• Halide substitution

  Cl-, Br-, I- will react with alcohol to form haloalkanes :

  ROH + HX → RX + H2O

  however reagent would be HX

  • acid catalyst such as concentrated H2SO4 is added to the mixture + is warmed to increase the rate of reaction
  • → when iodide is reacted then H3PO4 is used as H2SO4 oxidises iodine ions to iodine - so the yield of desire haloalkane is low