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ALDEHYDES AND KETONES I

ALDEHYDES AND KETONES I. CHAPTER 16. CHEMISTRY OF THE C=O GROUP. Sections 16.1 and 16.2 Nomenclature of Aldehydes and Ketones. Learn on your own. Sections 16.3-16.5 Review and Overview. Read on your own. Section 16.6 Cyanide addition. Lecture. Section 16.7

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ALDEHYDES AND KETONES I

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  1. ALDEHYDES AND KETONES I

  2. CHAPTER 16 CHEMISTRY OF THE C=O GROUP Sections 16.1 and 16.2 Nomenclature of Aldehydes and Ketones Learn on your own. Sections 16.3-16.5 Review and Overview Read on your own Section 16.6 Cyanide addition Lecture Section 16.7 Addition of Organometallics Totally review Section 16.8 Read on your own Bisulfite Addtion Sections 16.9-16.11 Lecture Jump to Sections 16.15-16.19 Lecture Go Back to Sections 16.12-16-14 Lecture

  3. STRUCTURE Aldehyde Ketone

  4. NOMENCLATURE

  5. IUPAC Nomenclature of Ketones • Choose the longest continuous carbon chain that contains the carbonyl carbon • Number from the end of the chain closest to the carbonyl carbon • Ketone ending is -one Do the ketonessection of Organic Nomenclature program!

  6. EXAMPLES 2-Pentanone 4-Ethyl-3-hexanone

  7. 3-Isopropylcyclopentanone or 3-(1-Methylethyl)cyclopentanone

  8. KETONES Common, or Trivial, Names • Name each group attached to the carbonyl group as an alkyl group • Combine into a name, according to the pattern: alkyl alkyl’ ketone NOTE: This is not all one word!

  9. Example of Common Names Methyl propyl ketone Diethyl ketone

  10. SPECIAL CASES diphenyl ketone dimethyl ketone benzophenone acetone A common laboratory solvent and cleaning agent methyl phenyl ketone KNOW THESE acetophenone

  11. IUPAC Nomenclature of Aldehydes • Choose the longest continuous carbon chain that contains the carbonyl carbon • Number from the end of the chain closest to the carbonyl carbon (carbon #1!) • Aldehyde ending is -al Do the aldehydessection of Organic Nomenclature program.

  12. EXAMPLES aldehyde group is always carbon 1 pentanal 3 1 4 2 2-chloro-3-methylbutanal

  13. RECOGNIZE THESE Common Names of the Aldehydes

  14. SPECIAL CASES formaldehyde benzaldehyde KNOW THESE acetaldehyde

  15. Forming Common Names of Aldehydes USE OF GREEK LETTERS ……. w is always the end of the chain, no matter how long a-chlorocaproaldehyde w-chlorocaproaldehyde ( a-chlorohexanal ) ( w-chlorohexanal )

  16. REACTIVITY OF THE C=O GROUP NUCLEOPHILIC ADDITION

  17. .. .. - d- : : : d+ + GENERALIZED CHEMISTRY THE CARBONYL GROUP nucleophilic at oxygen H+ or E+ electrophiles add here nucleophiles attack here Nu: electrophilic at carbon

  18. STEREOCHEMISTRY

  19. THE CARBONYL GROUP IS PLANAR (SP2 HYBRIDIZED) Nu: . . .. C O .. Nu: nucleophiles can attack from either top or bottom

  20. LUMO OF FORMALDEHYDE s*CH s*CO p* (LUMO) nO H H p sCO sCH .. Nu: nucleophiles add to the larger lobe (on carbon) :

  21. NUCLEOPHILIC ADDITION TO C=O MECHANISMS IN ACID AND IN BASE

  22. Nucleophilic Addition to Carbonyl Basic or Neutral Solution an alkoxide ion - or on adding acid Good nucleophiles and strong bases (usually charged) BASIC SOLUTION

  23. Nucleophilic Addition to Carbonyl Acid Catalyzed more reactive to addition than the un- protonated precursor (+) Acid catalysis speeds the rate of addition of weak nucleophiles and weak bases (usually uncharged). ACIDIC SOLUTION stronger acid protonates the nucleophile pH 5-6

  24. CYANOHYDRINS

  25. Addition of Cyanide :C N: Buffered to pH 6-8 a cyanohydrin In acid solution there would be little CN-, and HCN (g) would be a problem (poison). A cyanohydrin

  26. CYANIDE ION BONDS TO HEMOGLOBIN .. Cyanide bonds (irreversibly) to the site (Fe II) where oxygen usually bonds. CYANIDE IS IS A POISON .. You die of suffocation - lack of oxygen. HCN is a gas that you can easily breathe into your lungs.

  27. SYNTHESIS OF a-HYDROXYACIDS

  28. SYNTHESIS OF AN a-HYDROXYACID NaCN a cyanohydrin pH 8 acetophenone 1) NaOH/H2O/D 2) H3O+ Aldehydes also work unless they are benzaldehydes, which give a different reaction (benzoin condensation).

  29. HYDROLYSIS OF THE NITRILE GROUP

  30. SYNTHESIS OF NITRILES (AND CYANOHYDRINS) REVIEW C=O + NaCN C-OH CN cyanohydrin acetone R-X + NaCN R-CN + NaX SN2 nitrile ….. both can be hydrolyzed

  31. NaOH + H2O/D synthesis of carboxylic acids HYDROLYSIS OF THE CYANO GROUP (NITRILES) METHOD ONE : strong base + H2O + heat gas .. : .. - + : .. H3O+ neutralize OVER ALL .. : R-CN .. .. R-COOH Nitriles are hydrolyzed to carboxylic acids.

  32. synthesis of carboxylic acids HYDROLYSIS OF THE CYANO GROUP (NITRILES) METHOD TWO : strong acid + H2O + heat .. : H2SO4 + .. H2O/D .. OVER ALL no mechanism at this time R-CN R-COOH Nitriles are hydrolyzed to carboxylic acids.

  33. ORGANOMETALLICS REVIEW FROM CHAPTER 15

  34. These reagents cannot exist in acid solution Synthesis of Alcohols Addition of Organometallic Reagents ether (R-Li) :R - workup step alcohol

  35. Summary of Reactions of Organometallics with Carbonyl Compounds • Organometallics with ketones yield tertiary alcohols • Organometallics with aldehydes yield secondary alcohols • Organometallics with formaldehyde yield primary alcohols. • Organometallics with carbon dioxide yield carboxylic acids. All review to you etc.

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