Electrophilic addition reactions of alkenes There are some

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Electrophilic addition reactions of alkenes. There are some questions in the middle part of

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!

Electrophilic addition. Ethene and bromine liquid at room temperature.

Electrophilic addition. Ethene and bromine liquid at room temperature.

H H C H Electrophile Polarised

H H C H Electrophile Polarised

Carbocation H H C C C + H H Br δ+ __ δBr H

Carbocation H H C C C + H H Br δ+ __ δBr H H H C Brδ+ BrδCurly arrows H

H H H C C+ H H + Br Brδ+ __ δBr Bromide ion

H H H C C+ H H + Br Brδ+ __ δBr Bromide ion H

Electrophilic addition Saturated H H H C C Br Br H 1, 2 -dibromoethane

Electrophilic addition Saturated H H H C C Br Br H 1, 2 -dibromoethane Unsaturated

H H C C Brδ+ H H Mechanism H C C+ Br __ Brδ

H H C C Brδ+ H H Mechanism H C C+ Br __ Brδ H C C+ H Br BrδH H __ δ Br H H C C Br Br H

Write down the answers to the questions on a piece of paper. You will

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.

Electrophilic addition. Ethene and bromine liquid at room temperature.

Electrophilic addition. Ethene and bromine liquid at room temperature.

H H C H

H H C H

H H C C C + H H Br δ+ __ δBr H H

H H C C C + H H Br δ+ __ δBr H H H Brδ+ Brδ- C H

H H H C C+ + Brδ+ Br __ δBr H

H H H C C+ + Brδ+ Br __ δBr H

H H H C C Br Br H

H H H C C Br Br H

Q 1. From red-brown to colourless (not clear). Ethene and bromine liquid at room

Q 1. From red-brown to colourless (not clear). Ethene and bromine liquid at room temperature.

H H C H Q 2. Ethene is unsaturated because it has a double

H H C H Q 2. Ethene is unsaturated because it has a double bond between carbon atoms. Q 3. The δ+ end of the Br 2 acts as an electrophile

Q 5. The carbon only has a single + charge because only one of

Q 5. The carbon only has a single + charge because only one of the shared pair of electrons belonged to this carbon. H H C C C + H H Br δ+ __ δBr H H H Brδ+ Brδ- Q 4. There is a single – charge because one of the shared pair of electrons already belonged to this bromine. C H

Q 6. A carbocation. H H H C C+ + Brδ+ Br __ δBr

Q 6. A carbocation. H H H C C+ + Brδ+ Br __ δBr H Q 7. Curly arrows represent movement of a pair of electrons.

Q 8. The product is saturated. All the bonds between carbon atoms are saturated.

Q 8. The product is saturated. All the bonds between carbon atoms are saturated. H H H C C Br Br H Q 9. 1, 2 -dibromoethane Q 10. Electrophilic addition.

Well done!

Well done!