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Aldehydes and Ketones

Aldehydes and Ketones. Chapter 5. Aldehydes and Ketones. Functional group is O The carbonyl l l group C Aldehyde = Carbonyl group is 1° Ketone = Carbonyl group is 2° . Aldehyde. RCHO ArCHO Benzaldehyde. Ketones.

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Aldehydes and Ketones

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  1. Aldehydes and Ketones Chapter 5

  2. Aldehydes and Ketones • Functional group is O The carbonyl l l group C Aldehyde = Carbonyl group is 1° Ketone = Carbonyl group is 2°

  3. Aldehyde RCHO ArCHO Benzaldehyde

  4. Ketones RCOR ArCOAr ArCOR O C – C-C-C

  5. Naming Aldehydes • Drop –e from alkane and add –al Methanal Propanal 2-chlorohexanal

  6. Practice

  7. Naming Ketones (2 ways) • IUPAC - # chain from the end closest to the carbonyl, give the carbon #, drop –e add –one • Name the groups on either side of the carbonyl and follow with ketone  list groups by order of sixe of molar mass (smaller 1st)

  8. Practice 2-butanone methyl ethyl Ketone 3-hexanone ethyl propyl ketone Draw 2 – pentanone and name it the 2nd way

  9. Practice • For the “old” way to name a ketone to use a phenyl, the ring must be bonded directly to the carbonyl 3-phenyl-3-propanone ethyl phenyl ketone 4-phenyl – 3 – butanone/no secondary name

  10. Practice

  11. Preparation of Aldehydes • Oxidation of 1° Alcohols (lose H2) RCH2OH PCC CH2Cl2 RCHO + H2 Catalysts are PCC = Pyridinium chororchrmate, C5H6NCrO3Cl Dichloromethane = CH2Cl2

  12. Practice • Form Propanal by oxidation CH3CH2CH2OH  CH3CH2CHO + H2

  13. Practice 2. Oxidize 1-hexanol O C-C-C-C-C-C-OH (Catalyst) C-C-C-C-C-C-H + H2 CH3(CH2)4CH2OH (Catalyst) CH3(CH2)4CHO + H2

  14. Practice • Synthesize propanal (str) C-C-C + Cl2  C-C-C-Cl + HCl C-C-C-Cl + H2O  C-C-C-OH + HCl C-C-C-OH (Catalyst) C-C-C=O + H2

  15. The 2nd Reaction Type 2. Reduction of acid chlorides (add H2) + H2 (Pt/Pd) + HCl RCOCl + H2 (Pt/Pd) RCHO + HCl *Acid chlorides look like aldehydes, but have a –Cl where the end –H is. (We will look at them more closely later)

  16. Practice • Form propanal by reduction CH3CH2COCl + H2 (Pt/Pd) CH3CH2CHO + HCl

  17. Synthesis of Benzaldehyde • The =O is not directly on the benzene, so you can’t follow he steps for an alcohol – you have to use the following…

  18. Synthesis of Benzaldehyde + -AlCl3 + HCl + 2Cl2  + 2HCl + H2O  + 2HCl

  19. Preparation of Ketones 1. Oxidation of 2° alcohols OH O R-C-R’ (Catlaysts) R-C-R’ + H2 RCHOHR’ (Catlaysts) RCOR’ + H2

  20. Practice • Oxidize 2-pentanol (str, cond, name product) OH O C-C-C-C-C  (Catalyst) C-C-C-C-C + H2 2-pentanone/methyl propyl ketone CH3CHOH(CH2)2CH3 (Ctlyst) CH3CO(CH2)2CH3 + H2

  21. Practice • Form methyl ethyl ketone (str, cond, name reactant)

  22. Practice • Synthesize 3-heptanone (cond.) CH3(CH2)5CH3+Cl2CH3CH2CHCl(CH2)3CH3 + HCl CH3CH2CHCl(CH2)3CH3 + H2O  CH3CH2CHOH(CH2)3CH3 + HCl CH3CH2CHOH(CH2)3CH3  (Cats) CH3CH2CO(CH2)3CH3 + H2

  23. The 2nd Reaction Type 2. Friedel – Crafts Acylation - acyl group RCO O O ArH + R-C-Cl –AlCl3 R-C-Ar + HCl ArH + RCOCl –AlCl3 RCOAr + HCl Benzene must bond directly to the C=O

  24. Practice • Form ethyl phenyl ketone (str, cond) C-C-C-Cl + -AlCl3 C-C-C- + HCl CH3CH2COCl + C6H6 –AlCl3 CH3CH2COC6H5 + HCl Form pentyl phenyl ketone (str, cond)

  25. Rxns of Aldehydes and Ketones • Reduction of aldes and kets to alcohols O R-C-H + H2 –Pt/Pd R-C-OH RCHO + H2 –Pt/Pd RCH2OH O O R-C-R + H2 –Pt/Pd R-C-R RCOR + H2 –Pt/Pd RCHOHR

  26. Practice • Reduce 2-hexanone (str,cond, name prod) O OH C-C-C-C-C-C + H2–Pt/Pd C-C-C-C-C-C 2-hexanone CH3CO(CH2)3CH3 + H2–Pt/PdCH3CHOH(CH2)3CH3

  27. Practice • Reduce Pentanal (str,cond, name prod)

  28. The 2nd Reaction Type 2. Oxidation of aldehydes to carboxylic acids O *Carboxyl group: COOH -C-OH O O R-C-H –KMnO4 R-C-OH RCHO –KMnO4 RCOOH

  29. Examples • Oxidize ethanol O O C-C-H –KMnO4 C-C-OH ethanoic acid CH3CHO –KMnO4 CH3CO2H *To name a carboxylic acid (must be on the 1st C), drop –e from alkane and add –oic acid

  30. Examples • Synthanize pentanoic acid (cond) CH3(CH2)3CH3 + Cl2  CH3(CH2)3CH2Cl + HCl CH3(CH2)3CH2Cl + H2O CH3(CH2)3CH2OH + HCl CH3(CH2)3CH2OH–PCC/CH2Cl2CH3(CH2)3CHO + H2 CH3(CH2)3CHO –KMnO4 CH3(CH2)3CO2H

  31. 3RD Reaction Type • Rxn with alcohols to form hemiacetals and acetals *Works well with aldehydes but difficule with ketones

  32. Example with Ketone O H+ OH H+ OR’ R-C-R + R’OH  R-C-R + R’OH  R-C-R +H2O OR’ OR’ hemiacetal acetal RCOR + R’OH –H+ RCOR’(OH) + R’OH –H+ RC(OR’)2R + H2O

  33. Example with Aldehyde O H+ OH H+ OR’ R-C-H + R’OH  R-C-H + R’OH  R-C-H +H2O OR’ OR’ RCHO + R’OH –H+ RCHOR’(OH) + R’OH –H+ RCH(OR’)2 + H2O

  34. Practice Example React butanal w/ propanol (str, cond) O OH OH OH C-C-C-C-H + C-C-C–H+C-C-C-C-H + C-C-C O-C-C-C O-C-C-C -H+C-C-C-C-H + H2 O-C-C-C

  35. Practice Example • Condensed version of the previous example CH3(CH2)2CHO + CH3CH2CH2OH –H+ CH3(CH2)2CH(O(CH2)2CH3)(OH) + CH3CH2CH2OH –H+ CH3(CH2)2CH(O(CH2)2CH3)2 + H2

  36. Practice • React 2-pentanone with ethanol (str, cond)

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