Cheatography
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Chemical reactions involving alkenes
This is a draft cheat sheet. It is a work in progress and is not finished yet.
Synthesis : dehydration of alcohols
(removal of -OH group and H atom) |
Catalyst |
conc. H₂SO₄ / H₃PO₄ |
Condition |
heat / 170°C / 180°C |
Mechanism |
Elimination reaction |
Equation |
CH₃CH₂OH → CH₂=CH₂ + H₂O |
| |
(every product must be shown) |
|
follow Zaitsev rule
major product : alkene where doubly bonded carbon have greatest number of alkyl groups
Addition of hydrogen halides
Reagent |
HCl / HBr / HI |
Mechanism |
Electrophilic addition |
Equation |
CH₃-CH=CH₂ + HBr → CH₃-CHBr-CH₃ |
| |
(every product must be shown) |
Condition |
room temperature |
|
add hydrogen peroxide |
anti-Markovnikov rule |
|
follow Markovnikov's rule
major product : halo group attach to doubly bonded carbon with least number of H atoms
Oxidation / Baeyer test w/ KMnO₄
Addition of hydrogen halides
Polymerisation
n number of monomer join to form polymer |
Catalyst |
Ziegler |
Equation |
alkene → polyalkene |
Hydration
Reagent |
H₂O |
Condition |
250°C |
Catalyst |
dilute H₂SO₄ |
Equation |
CH₃CH=CCH₃-CH₃ + H₂O → CH₃CH₂C(OH)(CH₃)-CH₃ |
| |
(every product must be shown) |
produce electrophile H₃O⁺ |
|
follow Markovnikov's rule
major product : OH group attach to doubly bonded carbon with least number of H atoms
|
|
Synthesis : dehydrohalogenation
(removal of H atom and one halo group) |
Reagent |
NaOH / KOH |
Condition |
ethanol (as solvent), reflux |
Equation |
CH₃CHCl-CH₂CH₃ + NaOH → CH₂=CHCH₂CH₃ + H₂O |
| |
(every product must be shown) |
|
follow Zaitsev rule
major product : alkene where doubly bonded carbon have greatest number of alkyl groups
Halogenation
Reagent |
Cl₂ / Br₂ |
Catalyst |
CCl₄ / CH₂Cl₂ |
Mechanism |
Electrophilic addition |
Equation |
CH₂=CH₂ + Br₂ → CH₂BrCH₂Br |
Observation |
brown colour of bromine disappears |
| |
green colour of chlorine disappears |
Hydrogenation
Reagent |
H₂ |
Catalyst |
Ni / Pt / Pd |
Condition |
heat / 200°C |
Equation |
CH₂=CH₂ + H₂ → CH₃CH₃ |
Oxidation / Baeyer test
Step 1 |
Reagent |
O₂ |
Catalyst |
silver |
Condition |
450 K |
Equation |
CH₂=CH₂ → C₂H₄O (epoxyethane) |
|
Step 2 |
Equation |
C₂H₄O (epoxyethane) → CH₂(OH)-CH₂(OH) |
Reagent |
H₂O |
Catalyst |
dilute H₂SO₄ |
Condition |
60°C |
Oxidation / Baeyer test
Reagent |
KMnO₄ |
Condition |
cold condition, basic medium |
Equation |
CH₂=CHCH₃ + KMnO₄ → CH₂(OH)-CH(OH)CH₃ |
Observation |
purple colour of KMnO4 disappears |
| |
brown colour precipitate formed |
Oxidation / Baeyer test w/ silver catalyst
|
