Carboxylic Acids _amp; Derivatives

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					Carboxylic Acids &
     Dr. Michael P. Gillespie
      • Carboxylic acids contain a carboxyl group (-

      • The name carboxyl is derived from terms
        carbonyl and hydroxyl, the two structural units
        that make up the carboxyl group.

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   Carboxylic Acids: Structure
         & Properties
  • Carboxylix acids are characterized by the
    carboxyl group.

  • The carboxyl group consists of two very polar
    functional groups, the carbonyl group and the
    hydroxyl group.

  • Carboxylic acids are therefore very polar

      • They can hydrogen bond to one another and
            to water.
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        Carboxylic Acids: Structure
              & Properties
      • Consequently, they are soluble in water and
        boil at higher temperatures.

      • As the carbon content increases, the solubility
        decreases because the carboxylic acids
        become more hydrocarbonlike.

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                           Carboxyl Group

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        Some Important Carboxylic
      • Methanoic (formic) acid causes the burning
        sensation of ant bites.

      • Ethanoic (acetic) acid provides the zip to

      • Polymers of lactic acid are used as
        biodegradable sutures and biodegradable
        plastic bags (potato peels are a great source
        of this lactic acid).

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   Some Important Carboxylic
   • Butanoic (butyric) acid is the odor associated
     with rancid butter.

   • When these carboxylic acids react with
     alcohols they produce esters, which contribute
     to the fragrance and flavor of many fruits.

   • Octanoic (caprylic) acid contributes to hunger

      • Citric acid provides sharp taste to foods, is a
            food preservative, and an antioxidant.
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        Some Important Carboxylic
      • Lactic acid provides a tangy flavor.

      • Oxalic acid is found in spinach and rhubarb and
        contributes to the formation of kidney stones.

      • Benzoic acid is a preservative in soft drinks,
        pickles, jellies, etc.

      • Salicylic acid is a disinfectant.

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        Some Important Carboxylic
      • Acetylsalicylic acid is aspirin. Hippocrates
        identified a bitter extract from willow bark
        that reduced fevers and relieved pain.

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                Biodegradable Plastic
      • Polymers of lactic acid make sheets of plastic.
      • Polylactic acid (PLA) is produced by the
        fermentation of sugars.

      • Bacteria in soil can readily break down PLA.
      • When french fries are produced, nearly half of the
        potato is wasted (approximately 10 billion pounds
        of potato waste each year).
      • This potato waste can be used to make PLA.

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            Preparation of Carboxylic
      • Carboxylic acids are prepared by the oxidation
        of aldehydes and primary alcohols.

      • The primary alcohol is oxidized into an
        aldehyde, which is further oxidized into a
        carboxylic acid.

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                   Acid-Base Reactions
      • When strong bases are added to a carboxylic
        acid neutralization occurs.

      • This produces a carboxylic acid salt and water.

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      • Carboxylic acids react with alcohols to form
        esters and water.

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                           Esters: Structure &
      • Esters are mildly polar and have pleasant

      • Their boiling points and melting points are
        comparable to those of aldehydes and

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              Preparation of Esthers
      • Esters are formed from the reaction between
        a carboxylic acid and an alcohol.

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                 Hydrolysis of Esthers
      • An ester can undergo hydrolysis to revert back
        to the parent carboxylic acid and alcohol.

      • Saponification is the base catalyzed hydrolysis
        of an esther. Soaps are made by this process.

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                           Acid Chlorides
      • Acid chlorides are noxious chemicals formed in
        the reaction of a carboxylic acid and reagants
        such as PCl3 or SOCl2.

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                           Acid Anhydrides
      • Acid anhydrides are formed by the
        combination of an acid chloride and a
        carboxylate anion.

      • Acid anhydrides can react with an alcohol to
        produce an ester and a carboxylic acid.

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                     Chemistry of Flavor &
      • Carboxylic acids are
        often foul smelling.

      • Butyric acid produces
        the smell of rancid

      • When carboxylic acids
        are converted to esters
        they produce pleasant

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      • An alcohol can react with phosphoric acid to
        produce a phosphate ester (phosphoester).

      • When two phosphate groups are joined, the
        resulting bond is a phosphoanhydride bond.

      • These two functional groups are important to
        the structure and function of adenosine
        triphosphate (ATP), the universal energy
        currency of all cells.

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      • Thioesters are produced by the reaction
        between a thiol and a carboxylic acid.

      • This reaction is catalyzed by cellular enzymes.

      • This reaction helps with fatty acid metabolism.

      • Coenzyme A is the most important thiol in
        these reactions.

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