radical mechanisms

Question 1

why is ozone important

Answer 1

ozone absorbs large amounts of UV radiation which can be harmful to humans

Question 2

how is ozone created (mechanism)

Answer 2

O=O -> O+O (oxygen radicals)
O+O2 <-> O3 (reverse reaction requires UV)

Question 3

how do CFCs breakdown ozone (mechanism)

Answer 3

CFCl3 -> CFCl2(rad) + Cl(rad) initiation

Cl(rad) +O3 -> ClO(rad) +O2 propagation
ClO(rad) + O -> Cl(rad) +O2

note Cl radicals formed can react again in step 2

Question 4

how can nitrogen oxide breakdown ozone (mechanism)

Answer 4

NO + O3 -> NO2(rad) + O2
NO2(rad) + O -> NO + O2

Question 5

why is bromine/chlorine free radical substitution of alkanes less than ideal for synthesis

Answer 5

Multiple products are formed which decreases yield and requires separation steps to purify.

Question 6

how does free radical substitution take place using Cl or Br (mechanism)

Answer 6

Br-Br -> Br(rad) + Br(rad) (initiation, requires UV)

CH4 + Br(rad) -> CH3(rad) + HBr (propagation)
CH3(rad) + Br2 -> CH3Br + Br(rad)

CH3(rad) + CH3(rad) -> C2H6 (termination)
CH3(rad) + Br(rad) -> CH3Br
Br(rad) + Br(rad) -> Br2