Megha Palariya

1. S.P.C. Govt. College Ajmer.
2021-2022
M.Sc. Chemistry Sem. 1st
Student’s Name – Megha Palariya
Organic Chemistry Seminar

2. TOPIC- Free Radical Reaction And It’s Type

3. Content~
• Free Radical Introduction
• Types Of Free Radical Reaction
• Recombination
• Disproportionation
• Reaction With Olefin
• Reaction With Iodine And Metal
• Rearrangements

4. Introduction
• When A Covalent Bond Undergoes Homolytic fission, The Two
Departing Atoms Take One Electron Of The Binding Pair Of Electrons.
The Two Fragments Produced Carry An Odd Electron Each And Are
Called Free Radicals.

5. Reactions For Free Radicals
1). •Recombination
2). •Disproportionation
3). •Reaction With Olefin
4). •Reaction With Iodine And Metals
5). •Rearrangements

6. Recombination Reaction
• The Free Alkyl Radicals May Recombine To Form Hydrocarbons.
• Note- The Reaction Is Used In The Termination Step In The Free
Radical Polymerization For The Production Of Polymers.

7. Disproportionation Reaction
• At Higher Temperature The Alkyl Radical May Undergo
Disproportionation. The Ethyl Radical Disproportionates (i.e. One
radical takes Up hydrogen from Another free radical)
• Note- It Is Found That Coupling Takes Place With Unbranched Free
Radicals While Disproportionation Predominates With Brached
Radicals.

8. Reaction With Olefines
• The Alkyl Radicals Reacts With Olefins To Form A New Free Radical.
• The Newly Formed Free Radical Further Add On The Another Molecules Of
Olefin.
• Note- The Above Reaction Is Used As The Propagation Step In The
Polymerization Of Ethylene.

9. Reactions With Iodine And Metals-
The Alkyl Radicals May Combine With Iodine or Other Elements To
Form Alkyl Derivatives.

10. Rearrangements
Like Carbanions,the Free radicals undergo rearrangements Involving 1,2-Shifts of aryl group
via bridgehead intermediate.Thus, the Aldehyde
1). Undergoes H-abstration from the CHO group by Me3CO To yield the acyl radical.
2).Which loses CO to form the Radical.
3). The Rearrangement Involves the Migration of Ph via The bridged ion intermediate

11. Reference Book
• Reaction Mechanism And Reaganets In Organic Chemistry- By Dr. G.R. Chatwal {Himalaya
Publishing House}
• Reactive Intermediates in Organic Chemistry: Structure, Mechanism, and
Reactions- By Maya Shankar Singh
• Advanced Organic Chemistry- By Dr. Jagdamba Singh, Dr. L.D.S. Yadav {A
Pragati Edition}

12. ThankYou