123.202 Lecture 10 - alkenes

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123.202 lecture 10 alkenes

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123.202 Lecture 10 - alkenes

  1. 1. ..LECTURE TEN the last ©gonzales2010@flickr (mono)alkenes
  2. 2. PREVIOUSLY... diol formation HO OH KMnO4 H H
  3. 3. ozonolysis i. O3(g) ii. Zn/H2O O O cleaves alkenes
  4. 4. mechanismwell, the steps involved... O O O O O O O O Zn/H2O O O O
  5. 5. radical chemistry ©Renaissance Pictures
  6. 6. free radical to alkenes addition of HBr HBr ROOR H Br anti Markovnikov addition
  7. 7. mechanism step initiation O R 2x R O R O R O H Br O Br R H radical chain reaction
  8. 8. ‘curly fishhook’ a radical is one electron
  9. 9. ‘curly fishhook’ need two electrons to form a bond
  10. 10. mechanism step propagation Br Br H Br H Br Br Br
  11. 11. chain carrier Br
  12. 12. mechanism step termination Br Br Br Br Br Br Br Br
  13. 13. ©Oberazzi@flickr
  14. 14. radical stability < < missing one electron
  15. 15. 11 HBr addition to styrenes H HBr Br Br we H known
  16. 16. but... H Ph HBr Ph Br single product
  17. 17. ©Great Beyond@flickr
  18. 18. resonance stabilisation H Br H H H H Br benzylic cation H stable
  19. 19. NO resonance stabilisation H H Br

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