Reactions

Reactions

Alkanes
1. Combustion
  1. Exothermic
  2. Non-Toxic Products
  3. Example...
    Annotations:
    - C3H8 + 5O2 ===> 3CO2 + 4H2O
2. Halogenation
  1. Under UV Radiation
  2. Free Radical Mechanism
    1. Propagation
    2. Initiation
    3. Termination
  3. Mixture of Products
  4. Example...
    Annotations:
    - CH4 +CL2 =UV=> CH3CL + HCL CH3CL+CL2 =UV=> CH2CL2 +HCL etc...
Alkenes
1. Combustion
  1. Exothermic
  2. Smoky Flame
  3. Example...
    Annotations:
    - 2C3H6 + 9O2 ===> 6CO2+6H2O
2. Electrophilic Addition
  1. Bromination
    1. With Bromine
      1. Example...
        Annotations:
        H2C=CH2 + Br2 ===> Br-H2C-CH2-Br (dibromoalkane)
    2. With Bromine Water
      1. Example...
        Annotations:
        H2C=CH2 + Br2 + H2O ===> Br-H2C-CH2-OH + HBr (bromoalcohol)
      2. Test for alkene
        Decolourises
    3. Can be in dark
  2. Hydrobromination
    1. Example...
      Annotations:
      - H3C-CH=CH2 + HBR ===>
      1. Major Product
        Annotations:
        H3C-CH(Br)-CH3
      2. Minor Product
        Annotations:
        H3C-CH2-CH2-Br
3. Catalytic Addition
  1. Hydrogenation
    1. Example...
      Annotations:
      - H2C=CH2 + H2 =Pt, High Temp, High Pressure=>H3C-CH3
  2. Hydration
    1. Ethanol Manufacture
    2. Example...
      Annotations:
      - H2C=CH2(g) + H2O(g) =H3PO4, High Pressure, 300C=> H3C-CH2-OH
4. Oxidative Addition
  1. Test for alkenes
  2. Example...
    Annotations:
    - H2C=CH2 + [O] + H2O [O]=KMnO4, Acid/Alkali=> HO-H2C-CH2-OH (diol) If acid, purple is decolourised. If alkali, purple goes green
5. Addition Polymerisation
  1. Free Radical Mechanism
  2. Example...
    Annotations:
    - n H2C=CH2 =catalyst, pressure=> -(-H2C-CH2-)-n poly(ethene)
Halogenoalkanes
1. With Ammonia
  1. Example...
    Annotations:
    - R-X + NH3 =xs NH3, pressure, closed vessel=> R-NH2 + HX (primary amine) An additional mole of ammonia is required to react with HX formed. PTO for competing reaction...
    - R-X + R-NH2 ===> R2NH + HX (secondary amine)
2. With Aqueous KOH
  1. Test For R-X
    Annotations:
    - Neutralise with HNO3 Add AgNO3
    1. White Precipitate:- R-Cl
    2. Cream Precipitate:- R-Br
    3. Yellow Precipitate:- R-I
  2. Example...
    Annotations:
    - R-X + OH^- =aqueous KOH=> R-OH + X^-
  3. Rate
    1. R-I > R-Br > R-Cl
    2. Tert. > Secd. > Pri.
3. With Ethanolic KOH
  1. Elimination of HX
  2. Example...
    Annotations:
    - H3C-CH2X + OH^- =ethanolic KOH=> H2C=CH2 + H2O + X^-
Alcohols
1. With Sodium
  1. Example...
    Annotations:
    - 2C3H7OH +2Na ===> 2C3H7O^-Na^+ H2 (sodium propoxide)
2. Dehydration
  1. Example...
    Annotations:
    - C3H7OH =conc. H2SO4=> H3C-HC=CH2 + H2O (alkene)
3. Halogenation
  1. With Phosphorous trihalides
    1. Examples...
      Annotations:
      - For chloroalkane... 3C3H7OH + PCl3 ==> 3C3H7Cl +H3PO3
      - For bromoalkane... 3C3H7OH + P + 1.5Br2 =heat under reflux=> 3C3H7Br +H3PO3
      - For iodoalkane... 3C3H7OH + P + 1.5I2 =heat under reflux=> 3C3H7I +H3PO3
  2. With PCl5
    1. Test For OH Group
    2. Example...
      Annotations:
      - C3H7OH + PCl5 ==> C3H7Cl + POCl3 + HCl (steamy fumes, turn damp litmus paper red)
  3. With Thionyl Chloride
    1. Makes For Easily Purifiable Halogenoalkanes
    2. Example...
      Annotations:
      - C3H7OH + SOCl2 ==> C3H7Cl + SO2(g) + HCl(g)
  4. With Hydrogen Halides
    1. Examples...
      Annotations:
      - For chloroalkane...(CH3)3C-OH + HCl =conc. HCl=> C3H7Cl + H2O (only with tertiary alcohols)
      - For bromoalkane...C3H7OH + HBr =NaBr, conc. H2SO4, distill product=> C3H7Br +H2O
      - For iodoalkane... C3H7OH +HI =KI, conc. H3PO4, distill product=> C3H7I + H2O
4. Oxidation
  1. Primary
    Annotations:
    - R-CH2-OH + [O] =distilling=> R-C(=O)(-H) (aldehyde) [O] = K2Cr2O7 PTO if not distilled...
    - R-CH2-OH + 2[O] =boil under reflux=> R-C(=O)(-OH) (carboxylic acid)
  2. Secondary
    Annotations:
    - R2CH-OH + [O] ==> R-C(=O)(-R) (ketone)
  3. Tertiary
    Annotations:
    - R3C-OH + [O] ==> no reaction

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	Created by Robin M over 11 years ago