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Aldehid Keton


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Aldehid Keton

  2. 2. Aldehyde Ald h d STRUCTURE O C R = H, alkyl, aryl R H Ketone O R and R' = alkyl or aryl d lk l l C R and R' cannot be hydrogen! R R'
  4. 4. IUPAC Nomenclature of Ketones • Ch Choose th l the longest continuous carbon chain th t t ti b h i that contains the carbonyl carbon • Number from the end of the chain closest to the carbonyl carbon • Ketone ending is -one Do the ketones section of Organic Nomenclature g program!
  5. 5. EXAMPLES O C CH 2 CH 3 CH 2 CH 3 2-Pentanone O CH3 C CH2 CH2 CH CH3 CH2 CH3 4-Ethyl-3-hexanone
  6. 6. O CH CH3 CH3 3-Isopropylcyclopentanone
  7. 7. KETONES Common, Common or Trivial Names Trivial, • Name each group attached to the carbonyl group as an alkyl group • Combine into a name, according to the pattern: alkyl alkyl’ k t lk l lk l’ ketone NOTE: NOTE This is not all one word!
  8. 8. Example of Common Names O C CH 2 CH 3 CH 2 CH 3 Methyl propyl ketone O CH3 C CH3 CH2 CH2 Diethyl ketone
  9. 9. SPECIAL CASES O O C C CH3 CH3 diphenyl ketone dimethyl k t di th l ketone benzophenone acetone A common laboratory O solvent and cleaning agent g C CH3 methyl phenyl ketone KNOW THESE acetophenone
  10. 10. IUPAC Nomenclature of Aldehydes • Choose the longest continuous carbon chain that contains th carbonyl carbon t i the b l b • Number from the end of the chain closest to the carbonyl carbon (carbon #1!) • Aldehyde ending is -al Do the aldehydes section of Organic Nomenclature program.
  11. 11. EXAMPLES aldehyde group is CH2 CH2 O always carbon 1 H3C CH2 C H pentanal Cl CH3 3 CH 1 O 4 CH 2 C CH3 H 2 chloro 3 methylbutanal 2-chloro-3-methylbutanal
  12. 12. Common Names of the Aldehydes O O O C C C H H CH3 H H3C CH2 H Formaldehyde Acetaldehyde Propionaldehyde 1 2 3 O O C C H3C CH2 C H H3C CH2 CH2 C H Butyraldehyde Valeraldehyde 4 5 O C H3C CH2 CH2 CH2 CH2 H RECOGNIZE Caproaldehyde THESE 6
  13. 13. SPECIAL CASES O C H H O formaldehyde C H O benzaldehyde C H CH3 KNOW THESE acetaldehyde
  14. 14. Forming Common Names of Aldehydes USE OF GREEK LETTERS O C C C C C C C H ω ……. ε δ γ β α −− ω is always the end of the chain, no matter how long CHO CHO Cl Cl α-chlorocaproaldehyde chlorocaproaldehyde ω-chlorocaproaldehyde chlorocaproaldehyde ( α-chlorohexanal ) ( ω-chlorohexanal )
  16. 16. GENERALIZED CHEMISTRY THE CARBONYL GROUP nucleophilic at oxygen t electrophiles H+ or E+ add here .. δ- .. - O: :O : δ+ C C + nucleophiles attack here Nu: electrophilic at carbon
  18. 18. Nucleophilic Addition to Carbonyl Basic or Neutral Solution .. _ .. :O: O: an + -:Nu slow C alkoxide C ion Nu .. _ .. :O: :O H fast C + H2O C Nu or on adding acid Nu Good nucleophiles and strong b d t bases BASIC SOLUTION (usually charged)
  19. 19. Nucleophilic Addition to Carbonyl Acid Catalyzed + more reactive to .. :O H O: fast addition than the un- + + H C protonated precursor C .. .. + :O H O H slow + C C :Nu Nu (+) Acid catalysis speeds the rate of addition of ACIDIC SOLUTION weak nucleophiles and k l hil d stronger acid weak bases (usually uncharged). pH 5-6 protonates the nucleophile
  21. 21. Addition of Cyanide y :C N: Buffered to pH 6-8 .. _ :O : :O : _ R C R + CN R C R CN .. _ .. :O : :O H R C R + H2O R C R CN CN a cyanohydrin In acid solution there would be little CN-, A cyanohydrin and HCN (g) would be a problem (poison).
  22. 22. CYANIDE ION BONDS TO HEMOGLOBIN .. CYANIDE IS N Cyanide bonds IS A POISON C (irreversibly) to the .. site (Fe II) where CH3 oxygen usually bonds. H3C N N You di f Y die of Fe suffocation - N N lack of oxygen. H3C CH3 CH2CH2COOH CH2CH2COOH HCN is a gas that you can easily breathe into your lungs.
  24. 24. Synthesis of Alcohols Addition of Organometallic Reagents .. _ + :O : :O: M ether R M + R C R C (R-MgBr) R R R (R-Li) :R - H2O workup k + step H These reagents cannot .. exist in acid solution :O H R C R + M (OH)x alcohol l h l R
  25. 25. Summary of Reactions of Organometallics with Carbonyl Compounds All review • Organometallics with ketones yield to t you tertiary alcohols • Organometallics with aldehydes yield secondary alcohols • Organometallics with formaldehyde yield primary alcohols. • Organometallics with carbon dioxide yield carboxylic acids. etc.
  26. 26. HYDRATES
  27. 27. Addition of Water O O H + H C + H2O R C R' R R' O H aldehyde or ketone favored a hydrate hydrates are unstable most hydrates revert to an aldehyde and cannot be isolated or ketone as soon as they form in most cases O H O R C R' + H2O C R R' O H
  28. 28. ACID CATALYSIS RECALL H + O H .. H .. .. + :O :O H :O H + Acid catalysis enhances the reactivity of the carbonyl group - nucleophilic :Nu N addition proceeds more easily. weak nucleophiles can react Water is a weak nucleophile.
  29. 29. WATER ADDS TO THE CARBONYL GROUP OF ALDEHYDES AND KETONES TO FORM HYDRATES H catalyzed by a + trace of acid O H .. H .. .. .. + H H H :O :O :O :O C C O+ :O a hydrate .. H .. H .. H O H .. .. H H O H H .. + O H H .. for most compounds the equilibrium MICROREVERSIBILITY: favors the starting materials g In a reaction where all steps are p and you cannot isolate the hydrate reversible, the steps in the reverse reaction are the same as those in the forward reaction, reversed!
  30. 30. ISOTOPE EXCHANGE REVEALS THE PRESENCE OF THE HYDRATE O O18 an excess of H2O18 f 18 H+ shifts the equilibrium + H2O R R R R to the right excess O H +H2O18 -H2O R C R 18 O H exchange shows the presence of a symmetric intermediate
  31. 31. SOME STABLE HYDRATES these also indicate that hydrates are possible y p δ− Cl O Cl OH Cl C Cl C OH δ− δ+Cl H Cl H chloral chloral hydrate δ− 120o expected 60o required OH 109o expected O 60o required sp2 sp3 OH cyclopropanone l cyclopropanone l hydrate
  32. 32. SOME ADDITIONAL STABLE HYDRATES O O O OH H C C H C C OH glyoxal H H O O O OH Ph C C Ph C C OH H H phenylglyoxal
  34. 34. ACID CATALYSIS RECALL H + O H .. H .. .. + :O :O H :O H + Acid catalysis enhances the reactivity of the carbonyl group - nucleophilic :Nu N addition proceeds more easily. weak nucleophiles can react Alcohols are weak nucleophiles.
  35. 35. Addition of Alcohols TWO MOLES OF ALCOHOL WILL ADD addition of one mole O O H H+ hemiketal R C R' + ROH R C R' O R addition of second mole O H O R H+ R C R' + ROH R C R' + H O O R O R H an aketal The equilibria normally favor the aldehyde or ketone starting material, but we will show how they can be made.
  36. 36. ACETALS AND HEMIACETALS R R OH ROH R OR ROH C O C C OR OR H aldehyde H H hemiacetal acetal R R OH ROH R OR ROH C O C C OR OR R ketone R R (hemiketal)* (h ik t l)* (ketal)* (k t l)* *older term *older term
  37. 37. .. R OH + H 2S O4 R O H Like a + hydronium y H ion R H O + .. .. H + .. :O :O H :O H R C R R C R R C R .. O+ O H .. R H .. R .. ACID CATALYZED : FORMATION OF A first R O addition H HEMIACETAL .. H Normally the starting :O H material is favored - but a second molecule R C R + R O+ of alcohol can react .. H if in excess (next slide) : .. O hemiacetal R
  38. 38. FORMATION OF THE ACETAL ( from the hemiacetal ) remove R H O + H .. .. H O H H .. second .. H .. : .. O addition :O H + O H R R C R R C R R C R R C R + :O .. :O .. SN1 :O + :O R R R R hemiacetal Resonance stabilized .. .. .. carbocation H :O R R O: O R + H H + R O : R C R R C R H :O :O .. R .. R acetal
  39. 39. STABILITY OF ACETALS AND HEMIACETALS Most hemiacetals are not stable, except for those of sugars (see later) later). Acetals are not stable in aqueous acid, but they are stable to aqueous base base. OR H2SO4 ROH AQUEOUS ACID C C O + H2O OR ROH AQUEOUS OR NaOH BASE C no reaction OR H2O
  40. 40. ADDITION OF WATER AND ALCOHOLS WATER O H2O HO OH C hydrate y ALCOHOLS O R-O-H ROH R-O-H ROH HO OR RO OR C H2O hemiacetal acetal O acetals are RO OR H+ +2 ROH stable to base H2O but not to H2O aqueous acid no reaction NaOH
  42. 42. OKSIDASI ALDEHID DAN KETON • Keton tidak mudah dioksidasi • Aldehid sangat mudah dioksidasi menjadi dioksidasi, asam karboksilat Zat pengoksidasi : KMnO4, H, H2O
  43. 43. Reaksi Reduksi
  44. 44. Reaksi Reduksi • Reduksi aldehid menghasilkan alkohol primer • Reduksi keton menghasilkan alkohol sekunder • Zat pereduksi: H2, katalis H2 k li Zn/Hg, HCl
  45. 45. Reaksi Adisi-eliminasi
  46. 46. Reaksi Adisi-eliminasi • Aldehid + Amina Primer Imina • Aldehid + Amina sekunder Enamina • Aldehid + Amina tersier hidrazon
  47. 47. Ramalkan produk hemiasetal atau hemiasetal siklik dari: 1. 5 hidroksi 2 heksanon 1 5-hidroksi-2-heksanon dengan air 2. 1,3,4,5,6-pentahidroksi-2-heksanon dengan air 3. propanal dengan metanol 4. Aseton dengan 1,2,3-propanatriol
  48. 48. Ramalkan apa produk reaksi sikloheksanon dengan : 1. CH3NH2 2. (CH3)2NH