1. Electrophilic addition reactions of alkenes.
There are some questions in the middle part of the presentation so have a pen and paper ready.
There is some narration so turn the sound on!

2. Electrophilic addition.
Ethene and bromine liquid at room temperature.

3. H H C C H H
Electrophile
Polarised
Brδ+
Brδ-

4. H H H H C C C C H H H H Brδ+ Brδ- Brδ- Carbocation Br δ+ Curly arrows__
Curly arrows

5. H H H H H C C H H C C H + + Br
Brδ+
Brδ- __
Bromide ion
Brδ- __

6. Electrophilic additionBr Br
Saturated
1,2-dibromoethane
Unsaturated

7. Brδ C
Brδ+
Brδ- H Br __ +
Mechanism
Brδ H C Br __ +

8. Write down the answers to the questions on a piece of paper.
You will be given the answers in the final part of the presentation.

9. Electrophilic addition.
Ethene and bromine liquid at room temperature.

10. H H C C H H
Brδ+
Brδ-

11. H H H H C C C C + H H H H
Brδ+
Br δ+
Brδ-
Brδ- __

12. H H H H H C C H H C C H + + Br
Brδ+
Brδ- __
Brδ- __

13. H H H C C H Br Br

14. Ethene and bromine liquid at room temperature.
Q1. From red-brown to colourless (not clear).
Ethene and bromine liquid at room temperature.

15. Q3. The δ+ end of the Br2 acts as an electrophile
Q2. Ethene is unsaturated because it has a double bond between carbon atoms. H H C C H H
Q3. The δ+ end of the Br2 acts as an electrophile
Brδ+
Brδ-

16. H H H H C C C C H H H H Brδ+ Brδ- Brδ- Br δ+
Q5. The carbon only has a single + charge because only one of the shared pair of electrons belonged to this carbon. H H H H C C C C + H H H H
Brδ+
Br δ+
Brδ-
Brδ- __
Q4. There is a single – charge because one of the shared pair of electrons already belonged to this bromine.

17. Q7. Curly arrows represent movement of a pair of electrons.
Q6. A carbocation. H H H H H C C H H C C H + + Br
Brδ+
Brδ- __
Q7. Curly arrows represent movement of a pair of electrons.
Brδ- __

18. Q10. Electrophilic addition.
Q8. The product is saturated. All the bonds between carbon atoms are saturated. H C C H Br Br
Q9. 1,2-dibromoethane
Q10. Electrophilic addition.

19. Well done!