Preparation of a Halogenoalkane
Experiment 2
Title: preparation of a halogenoalkane
Objective: To synthesis 2-cholo-2-methylpropane by using corresponding alcohol and HCl(aq). The reaction is via SN1 of tertiary alcohol.
Techniques: i) Distillation of the reactant and the product ii) Purification by separating funnel
Theory: In the experiment, SN1 reaction take place, HCl is added to initiate the reaction. The R-OH attack the H+ with the lone pair on O. Then the R-O+H2 bond breaks the release a water molecule and a carbonium ion.
The Cl- will then attack the carbonium ion forming a 2-cholo-2-methylpropane. Since Cl lack ability of forming hydrogen bond, this compound cannot dissolve in water, hence forming a 2 layer liquid.
Then add NaHCO3, it is used to clean the excess HCl in organic layer. Later, NaSO4 is added to remove the small amount of water in organic layer. Distillation is then carried to purify the product.
Apparatus:
Separating funnel
Electronic balance
Test tube
Dropper
Distillation quick fit
Filter funnel
Filter paper
Bunsen burner
Beaker
Insulating mat
Tripod
Wire gauze
Chemical:
2-methylpropan-2-ol
HCl
Sodium hydrogencarbonate
Sodium sulphate
Anti-bumping granules
Set up
Procedure: 1. 10 cm3 of 2-methylpropane-2-ol was added into a measuring cylinder. The total mass was measured and recorded
2. The alcohol was poured in a separating funnel the mass of measuring cylinder was recorded. 25cm3 of concentrated HCl was added into the funnel in 10 portions. After each addition, the funnel was closed and inverted several times. The switch was opened for releasing pressure.
3. The reaction mixture was left for half an hour.
4. A sample distillation set-up was set up and a small flask was weighed for collecting the distillate.
5. The organic layer was collected from the separating funnel.
6. Some sodium hydrogencarbonate was added 2cm3 at a time until no pressure can be released.
7. Again, the organic layer was collected. The organic
Title: preparation of a halogenoalkane
Objective: To synthesis 2-cholo-2-methylpropane by using corresponding alcohol and HCl(aq). The reaction is via SN1 of tertiary alcohol.
Techniques: i) Distillation of the reactant and the product ii) Purification by separating funnel
Theory: In the experiment, SN1 reaction take place, HCl is added to initiate the reaction. The R-OH attack the H+ with the lone pair on O. Then the R-O+H2 bond breaks the release a water molecule and a carbonium ion.
The Cl- will then attack the carbonium ion forming a 2-cholo-2-methylpropane. Since Cl lack ability of forming hydrogen bond, this compound cannot dissolve in water, hence forming a 2 layer liquid.
Then add NaHCO3, it is used to clean the excess HCl in organic layer. Later, NaSO4 is added to remove the small amount of water in organic layer. Distillation is then carried to purify the product.
Apparatus:
Separating funnel
Electronic balance
Test tube
Dropper
Distillation quick fit
Filter funnel
Filter paper
Bunsen burner
Beaker
Insulating mat
Tripod
Wire gauze
Chemical:
2-methylpropan-2-ol
HCl
Sodium hydrogencarbonate
Sodium sulphate
Anti-bumping granules
Set up
Procedure: 1. 10 cm3 of 2-methylpropane-2-ol was added into a measuring cylinder. The total mass was measured and recorded
2. The alcohol was poured in a separating funnel the mass of measuring cylinder was recorded. 25cm3 of concentrated HCl was added into the funnel in 10 portions. After each addition, the funnel was closed and inverted several times. The switch was opened for releasing pressure.
3. The reaction mixture was left for half an hour.
4. A sample distillation set-up was set up and a small flask was weighed for collecting the distillate.
5. The organic layer was collected from the separating funnel.
6. Some sodium hydrogencarbonate was added 2cm3 at a time until no pressure can be released.
7. Again, the organic layer was collected. The organic