Reactions Of Alkenes + Conditions

Reaction conditions & reagents for elimination/dehydration of alcohols to form alkenes and water reactions

Reagents: Concentrated H3PO4 acid catalyst

Conditions: Heat

Products of limination/dehydration of alcohols

alkene and H2O

Reaction conditions & reagents for electrophilic addition of Br2

Reagent: Cl2 or Br2 dissolved in CCl4

Condition: room temp. & no light

What is electrophilic addition?

• C=C bond is electron rich and attracts electrophiles.

• Electrophiles are electron deficient and accepts a pair of electrons to form a covalent bond 

• The alkene molecule would undergo electrophilic addition where two substances will react together and forma single product 

What is observed when Br2 is added to alkene?

Orange-red colour rapidly decolourises to form colourless halogenoalkane product

Reaction conditions and reagents needed for electrophilic addition of hydrogen halides

Reagents: Gaseous HCl, HBr, or HI

Condition: Room temp.

Product formed from electrophilic addition of hydrogen halides

Halogenoalkanes 

Reaction conditions and reagents needed for electrophilic addition of steam (hydration)

Reagents: Steam and conc H3PO4 acid catalyst

Conditions: 300 degree Celsius and 70atm

Product formed from electrophilic addition of steam (hydration)

alcohol

Reagent and reactions conditions needed for education via catalytic hydrogenation (catalytic addition of hydrogen) 

Reagent: H2 (g)

Conditions: Ni catalyst 

Product formed from catalytic hydrogenation (catalytic addition of hydrogen)

alkanes

Reagent and reaction conditions for mild oxidation (oxidative addition)

reagent: dilute alkaline KMnO4

condition: COLD

Product formed from mild oxidation (oxidative addition)

Diol

Observation of mild oxidation (oxidative addition)

Purple KMnO4 decolourises

Brown PPT of MnO2 forms 

Reagents and reaction conditions for oxidative cleavage) strong oxidation

Reagent: KMnO4 in dilute H2SO4

Conditions: Heat under reflux

Product formed from oxidative cleavage) strong oxidation: 2 hydrogen atoms attached

CO2 and H2O

Product formed from oxidative cleavage) strong oxidation: 1 hydrogen atom and 1 R group

Carboxylic acid

Product formed from oxidative cleavage) strong oxidation: two R groups

Ketone

What is observed in oxidative cleavage) strong oxidation:

Purple KMnO4 decolourises