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Ketones, Aldehydes

Ketones, Aldehydes. CH21 PS CLASS. Recall the many times we’ve synthesized these! I command thee. Oxidation of R-OH ( Periodinane , CrO 3 /Na 2 Cr 2 O 7 ) Hydration of Alkynes ( keto-enol tautomerism ) H 3 O+/HgSO 4 , BH 3 /H 2 O 2, OH-, etc… Friedel -Crafts ACYL ation of Aromatics

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Ketones, Aldehydes

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  1. Ketones, Aldehydes CH21 PS CLASS

  2. Recall the many times we’ve synthesized these! I command thee. • Oxidation of R-OH • (Periodinane, CrO3/Na2Cr2O7) • Hydration of Alkynes (keto-enoltautomerism) • H3O+/HgSO4, BH3/H2O2,OH-, etc… • Friedel-Crafts ACYLation of Aromatics • (acid halide + AlCl3)

  3. REACTIONS OF ALDEHYDES/KETONES • Oxidation of Aldehydes • Nucleophilic Additions (overview) • Hydride (H-) and Grignard (R-) as Nucleophiles • Water addition (hydrate/diol/geminaldiol formation) • Alcohol addition (acetal formation) • Amine addition (imine formation) • Conjugate Nucleophilic Addition Reactions

  4. Major Synthesis

  5. Major Synthesis

  6. Major Synthesis

  7. Major Synthesis

  8. Major Synthesis

  9. Major Synthesis

  10. Major Synthesis

  11. Oxidation of Aldehydes Where [O] = CrO3 among others.

  12. Nucleophilic Addition Rxns Slightly different mechanisms in acid or base. Neutral vs. Negatively charged Nucleophile General picture (basic):

  13. Reactivity Notes: Less steric hindrance with aldehyde Benzaldehyde less reactive due to resonance stabilization.

  14. Reduction of Ketones/Aldehydes

  15. Addition of Grignard Reagent

  16. Grignard Reagents + carbonyls

  17. Practice! COME UP WITH PAIRS, More than one answer for some.

  18. Practice!

  19. Hydrate formation/ GeminalDiols

  20. Basic vs. Acidic ACIDIC: Carbonyl is converted to a stronger ELECTROPHILE as CABON BECOMES MORE POSITIVE. BASIC: Strong nucleophile attacks, as in Nu-

  21. Problem

  22. Acetal formation ACID CATALYZED… AGAIN, CARBONYL MADE INTO BETTER ELECTROPHILE.

  23. Acetal Formation

  24. Acetal Formation

  25. Acetal Formation 2 alcohols/ 1 diol can be used to ‘protect’ an aldehyde or ketone from a reaction.

  26. Nuc. Addition of Amines to form: Imines (bisayaka dong?) Amine must have 2 protons, RNH2

  27. Problems Predict the Products!

  28. Problems

  29. Conjugate Nucleophilic Addition Rxns

  30. Conjugate Nucleophilic Addition Rxns THE DOUBLE BOND IS EFFECTIVELY “POLARIZED” INTO A NEGATIVE REGION THAT’S RESONANCE STABILIZED, AND A POSITIVE REGION AT THE BETA-CARBON.

  31. Predict the product + HCN

  32. Practice

  33. Predict the Products NaBH4/H3O+ NH2OH/HCl 2 CH3OH /acid CH3MgBr then acid

  34. Predict the Products NH2OH/HCl NaBH4/H3O+ 2 CH3OH /acid CH3MgBr then acid

  35. Predict the Products NH2OH/HCl NaBH4/H3O+ 2 CH3OH /acid CH3MgBr then acid

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