Tests/ Experiments with Alcohols

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  • Created by: Dharpana
  • Created on: 11-03-13 01:40
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  • Tests/ Experiments with Alcohols
    • Combustion
      • Small Amount of Alcohol is ignited on a deflagrating spoon
        • FUME CUPBOARD
        • Burns with a CLEAN and COLOURLESS FLAME
          • alcohol + oxygen -> carbon dioxide and water
            • C2H5OH + 3(O2) -> 2(CO2) + 3(H2O)
          • C2H5OH + 3(O2) -> 2(CO2) + 3(H2O)
      • Burns with a CLEAN and COLOURLESS FLAME
        • alcohol + oxygen -> carbon dioxide and water
      • Reaction with Sodium
        • Add a small piece of sodium to Xcm3 a particular alcohol
        • Similar to the Reaction of Sodium with WATER - but much less violent
          • Alcohols and Water both contain an OH GROUP - chemically similar, therefore they react in similar ways
            • i.e. both are polar
          • Effervescence is seen: hydrogen gas is produced
            • Sodium does NOT MELT
              • alcohol + sodium -> sodium alcoxide + hydrogen gas
            • alcohol + sodium -> sodium alcoxide + hydrogen gas
          • Sodium does NOT MELT
            • C2H5OH + Na -> C2H5ONa + 1/2(H2)
          • Oxidation
            • 1: Add some potassium dichromate VI to some dilute sulphuric acid
              • acidifies the potassium dichromate - turns it orange
              • 2: Add 2-3 drops alcohol
                • HEAT
                • 3: Add 2-3 drops sodium carbonate
                  • PRIMARY ALCOHOL
                    • orange K2CR2O7 solution turns green
                      • SECONDARY ALCOHOL
                        • a ketone is produced [C=O]
                          • Boil with Benedicts Solution
                            • NEGATIVE RESULT: solution stays dark blue
                      • primary and secondary alcohols are oxidised by the dichromate ion - this reduces it to green Cr3+ ions
                      • a ketone is produced [C=O]
                        • Boil with Benedicts Solution
                          • NEGATIVE RESULT: solution stays dark blue
                    • an aldehyde is produced [CH=O]
                      • orange K2CR2O7 solution turns green
                        • SECONDARY ALCOHOL
                          • primary and secondary alcohols are oxidised by the dichromate ion - this reduces it to green Cr3+ ions
                        • partial oxidation
                        • this can be further oxidised to a carboxylic acid
                          • complete oxidation
                            • colourless vapour & hot glass
                          • REFLUX/ CONC H2S04/  EXCESS Oxidising Agent (K2CR2O7)
                          • sour vinegar smell
                            • fizzing with sodium carbonate solution - acidic product
                              • Boil with Benedicts Solution
                                • NEGATIVE RESULT: solution stays dark blue
                        • Limited Oxidising Agent (K2CR207) - PARTIAL
                          • NO CONDENSER
                          • colourless vapour produced
                            • glass becomes hot - EXOTHERMIC
                        • bitter almond smell
                          • no reaction - ALDEHYDE produced; not acidic
                          • Boil with Benedicts Solution
                            • POSITIVE RESULTS: colour change from dark blue to red
                    • TERTIARY ALCOHOL
                      • orange solution stays orange
                        • TERTIARY ALCOHOLS CANNOT BE OXIDISED
                  • PRIMARY ALCOHOL
                    • an aldehyde is produced [CH=O]
                      • partial oxidation
                      • this can be further oxidised to a carboxylic acid
                        • complete oxidation
                          • colourless vapour & hot glass
                        • REFLUX/ CONC H2S04/  EXCESS Oxidising Agent (K2CR2O7)
                        • sour vinegar smell
                          • fizzing with sodium carbonate solution - acidic product
                            • Boil with Benedicts Solution
                              • NEGATIVE RESULT: solution stays dark blue
                      • Limited Oxidising Agent (K2CR207) - PARTIAL
                        • NO CONDENSER
                        • colourless vapour produced
                          • glass becomes hot - EXOTHERMIC
                      • bitter almond smell
                        • no reaction - ALDEHYDE produced; not acidic
                        • Boil with Benedicts Solution
                          • POSITIVE RESULTS: colour change from dark blue to red
                  • TERTIARY ALCOHOL
                    • orange solution stays orange
                      • TERTIARY ALCOHOLS CANNOT BE OXIDISED
                • temperature rises - solutions fizzes
            • Halogenation
              • Chlorination
              • Substitution Reaction
              • Bromination
                • Alcohol is heated under reflux with (solid) potassium bromide and 50% sulphuric acid
                  • 1: a hydrogen bromide is produced
                    • from dissociated H+ and Br- ions
                    • 2: hydrogen bromide reacts with alcohol to form bromoalkane
                    • KBr +H2SO4 -> KHSO4 + HBr
                    • potassium bromide + sulphuric acid -> potassium bisulphate + hydrogen bromide
                      • KBr +H2SO4 -> KHSO4 + HBr
                  • CONCENTRATED H2SO4 will oxidise the halide and instead produce bromine/iodine and sulphur
                    • 1: damp red phosphorus  and iodine produce phosphorus triiodide
                      • 2: phosphorus triiodide reacts with an alcohol to form an iodoalkane
                        • C2H5OH + PI3 -> 3(CH3CH2I) + H3PO3
                        • ethanol + phosphorus triiodide -> iodoethane + phosphoric acid
                      • 2P + 3(I2) -> 2(PI3)
                      • phosphorus + iodine -> phosphorus triiodide
                        • 2P + 3(I2) -> 2(PI3)
                      • HEAT
                  • HEAT & REFLUX
              • Iodination
                • 1: damp red phosphorus  and iodine produce phosphorus triiodide
                  • 2: phosphorus triiodide reacts with an alcohol to form an iodoalkane
                    • C2H5OH + PI3 -> 3(CH3CH2I) + H3PO3
                    • ethanol + phosphorus triiodide -> iodoethane + phosphoric acid
                  • phosphorus + iodine -> phosphorus triiodide
                    • HEAT
            • HEAT & REFLUX

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