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Organic Chemistry Reviews Chapter 18

Organic Chemistry Reviews Chapter 18. Cindy Boulton April 19, 2009. Carboxylic Acids and Derivatives. Carboxylic Acid Ester Acid Anhydride Acid Chloride/Acyl Chloride Amide Nitrile. Carboxylic Acid. Nomenclature Name parent chain, based on number of carbons Drop –e and add –oic acid

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Organic Chemistry Reviews Chapter 18

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  1. Organic Chemistry ReviewsChapter 18 Cindy Boulton April 19, 2009

  2. Carboxylic Acids and Derivatives • Carboxylic Acid • Ester • Acid Anhydride • Acid Chloride/Acyl Chloride • Amide • Nitrile

  3. Carboxylic Acid • Nomenclature • Name parent chain, based on number of carbons • Drop –e and add –oic acid • Carboxyl group will always be on the end of a carbon chain • Consists of a carbonyl (C=O) and hydroxyl (O-H) groups • Common Names • Methanoic Acid or Formic Acid • Fire ant bites • Ethanoic Acid or Acetic Acid • Propanoic Acid or Propionic Acid • Butanoic Acid or Butyric Acid

  4. Carboxylic Acid • Dicarboxylic Acids • Oxalic Acid • 2 Carboxyl groups joined together • Malonic Acid • 1 Hydrocarbon separating two carboxyl groups • Succinic Acid • 2 Hydrocarbons separating two carboxyl groups • Water solubility • Carboxylic Acids with 1-4 Carbons are soluble due to the large polarity and hydrogen bonds are able to form • Carboxylic Acids with 5-18 Carbons have decreasing solubility due to the increase of nonpolar hydrocarbons

  5. Carboxylic Acids • Inductive Effect • Carboxylic Acids are very acidic • The electronegative element oxygen causes the electrons from the attached hydrogen to be strongly pulled • It is very easy to remove the first hydrogen, very low pKa value • The second hydrogen is much more difficult to remove, higher pKa value • The inductive effect is decreased by alkyl groups between carboxylic acids as the carboxyl groups are spaced farther apart

  6. Nomenclature • Esters • Carboxyl group but a carbon, not a hydrogen, is attached • Parent chain named including the carbonyl carbon • Drop –e and add –oate • The other carbon group attached instead of hydrogen is placed in front of the name • Anhydride • Combining of 2 Carboxylic Acids and removing water • Name each carboxylic acid (alphabetically) before anhydride

  7. Nomenclature • Acid Chlorides • Carbonyl with chloride and carbon group attached • Name carbon group, drop –e, and add -oyl • Amide • NH2 • Carbonyl with amide and carbon group attached • Name carbon group, drop –e, and add –amide • If a something other than hydrogen is attached to the nitrogen, it is placed in front of parent name and indicated by (N-)

  8. Spectroscopy • Carboxylic Acid • IR: • C-H at 3000 and O-H at 3300 combined • C=O at 1700 • 1H-NMR: • Carboxyl hydrogen at 9-12 • 13C-NMR: • Carboxyl carbon at 170-180

  9. Spectroscopy • Ester • IR: • C-H at 3000 • C=O at 1700 • 1H-NMR: • Not easy to identify • Hydrogens are shifted downfield due to desheilding • 13C-NMR: • Carbonyl carbon at 170-180 • Nitrile • 13C-NMR: • Carbon at 110-120

  10. Synthesis of Carboxylic Acids • Oxidation of Alkenes • Alkene has a Hydrogen attached • 1) KMnO4, heat, OH / 2) H3O+ • C-H  C-O-H • Alkene double bond cleaved and Carbonyl bond formed • Oxidation of Primary Alcohols and Aldehydes • Aqueous Chromic Acid • Cr6+/H2O • Side Chain Oxidations • Monosubstituted Benzene ring with primary or secondary alkyl group attached • 1) KMnO4, heat, OH / 2) H3O+

  11. Synthesis of Carboxylic Acids • Oxidation of Methyl Ketones • Haloform Reaction • Ketone or Secondary Alcohol with methyl group attached react with Iodoform reagent to form carboxylic acid • Combination of Grignard Reagent • R-MgBr + CO2 Carboxylate + (H+)  Carboxylic Acid • Reagents must be tightly sealed to prevent this from occuring • Mechanism • Carbanion reacts with Carbon Dioxide

  12. Nucleophilic Substitutionat the Acyl Carbon • Nucleophile attacks carbonyl carbon • Leaving group leaves • Weaker base • Large, stable anion

  13. Acyl Chlorides • Formed by Carboxylic Acid reacting with SOCl2, PCl3, or PCl5 • Acyl Chloride is most reactive • Chloride is good leaving group • Reacts with nucleophiles binding to the carbonyl carbon • Anhydrides • Esters • Carboxylic Acids • Amides

  14. Acid Anhydride • Acyl Chloride + Carboxylate  Acid Anhydride • Phthalic Anhydride • Two adjacent carboxyl groups attached to a benzene ring react • Stable

  15. Synthesis of Esters • Acyl Chloride and Alcohol • Nucleophile (alcohol) attacks carbonyl carbon • Carboxylate acts as a good leaving group • Carboxylic Acid and Alcohol • Nucleophile (alcohol) attacks • Methyl, primary, or secondary • Sterics • Leaving group: hydroxyl group • Not the best leaving group • Acid Catalyzed

  16. Lactones • Cyclic Esters • α – lactone • Unstable, ring strain • Carbonyl Carbon, Oxygen, 1 Carbon (α) • β – lactone • Carbonyl Carbon, Oxygen, 2 Carbons (α,β) • α Carbon is closest to Carbonyl Carbon • γ – lactone • Carbonyl Carbon, Oxygen, 3 Carbons (α,β,γ) • δ – lactone • Carbonyl Carbon, Oxygen, 4 Carbons (α,β,γ,δ)

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