Mechanism: Free Radical Substitution

Question 1

A free radical is a species with

Answer 1

one (or more than one) unpaired electrons

Question 2

A free radical reaction is a reaction involving free radicals and is a three-step reaction:
Initiation is the first step and involves

Answer 2

breaking a covalent bond using energy from ultraviolet (UV) light from the sun to form two free radicals

Question 3

The propagation step is the second step in which the

Answer 3

free radical can attack reactant molecules to form even more radicals

These in turn can again attack other molecules to form more free radicals and so on

Question 4

In the termination step

Answer 4

two free radicals react together to form a product molecule

Question 5

Remember:Initiation = ……………….
Propagation = ……….
Termination = ………………………
Read the question carefully - sometimes they specify which termination step you should include.

Answer 5

molecule forming two radicals

always two steps, a molecule and a radical reacting to form a different molecule and radical combination

two radicals reacting to form a molecule