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Side chain PowerPoint Presentation

Side chain

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Side chain

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  1. Side chain It’s the aliphatic portion of the alkenylbenzene.

  2. Benzylic Radicals and Cations • Benzyl radical: is a specific name for the radical produces from the Hydrogen abstraction from the methyl group of methylbenzene (tolune).

  3. Benzylic Radicals and Cations • Benzylic radical: is the general name applies to all radicals that have unpaired electron on the side- chain carbon atom that attached directely to the benzene ring.

  4. Benzylic Radicals and Cations • Benzylic hydrogen atoms: is the hydrogen atom of the carbon atom that directly attached to the benzene ring.

  5. Benzylic Radicals and Cations • Benzyliccation: is the departure of a leaving group (LG) from a benzylic position.

  6. Benzylic Radicals and Cations • They have approximately the same stabilities, this stability can be explained by resonance theory.

  7. Halogenation of the side chain

  8. Bromination Chlorination

  9. Benzylichalogenation Chain Initiation Step 1 Chain propagation Step 2

  10. Benzylichalogenation Step 3 Chain Termination Step 4

  11. Oxidation of the side chain • The oxidation can be carried out by the action of hot alkaline potassium permanganate.

  12. Oxidation of the side chain • Oxidation of the side- chain take place initially at the benzylic carbon; alkylbenzenes with alkyl group longer than methyl are ultimately degraded to benzoic acids:

  13. Oxidation of the side chain • Reaction:

  14. Procedure: • Dissolve 1 gm NaOH in 75 ml of distal water in round flask (500ml). • Add 7 gm of potassium permanganatr KMnO4, and 4 ml of toluene. And heat it on hot plate for 3 hr.

  15. Procedure: • In case if the KMnO4 color don’t change, add few drops of ethanol until the violet color disappear. • Filtre by Buchner, take the filtrate and heat it until the volume reduced to 10- 20 ml.

  16. Procedure: • Cool the filtrate on a iced cold water, then add HCL drop wise until the ppt stop. • Fitre by Buchner.

  17. Thank you