Mechanism of the Reaction Between Ethene and Bromine - Other Reactions

Question 1

This mechanism also stands for the addition of what to ethene?

Answer 1

Cl2 and HCl

Question 2

This mechanism also stands for the addition of Cl2 and HCl to what?

Answer 2

Ethene

Question 3

Describe how the mechanism occurs in the case of Cl2.

5

Answer 3

Polarisation of the Cl-Cl bond occurs as a result of the repulsion caused by the electrons in the double bond

Heterolytic fission occurs giving rise to Cl+ and Cl- ions

The Cl+ species attacks the C=C double bond first and then forms a bond with one of the carbon atoms

This leaves the other carbon atom positively charged (carbonium atom)

The Cl- ion attacks the carbonium ion to form 1,2-dichloroethane

Question 4

Describe how the mechanism occurs in the case of HCl.

5

Answer 4

Increased polarisation of the already polar HCl bond occurs, as a result of repulsion by the electrons in the double bond (of ethene)

This leads to heterolytic fission forming H+ and Cl- ions

The H+ ions attacks the C=C double bond first and forms a bond with one of the carbon atoms

This leaves the other carbon atom positively charged (carbonium ion)

The Cl- ion then attacks the carbonium ion to form chloroethane

Question 5

Why is there no evidence for the formation of a cyclic intermediate in the case of the addition of HCl to ethene?

Answer 5

This is because the H atom is too small to form a ring compound

Question 6

There is no evidence for the formation of a cyclic intermediate in the reaction between what and ethene?

Answer 6

HCL

Question 7

What cannot be formed in the reaction between HCL and ethene?

Answer 7

A cyclic intermediate