Carboxylic Acids, Esters, and Other Derivatives

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• Carboxylic Acids, Esters, and Other Derivatives

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Carboxylic Acids

• Carboxylic acids contain the carboxyl group on
  carbon 1.
• O
• ??
• CH3 COH CH3COOH CH3CO2H
• carboxyl group

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Naming Carboxylic Acids

• Formula IUPAC
  alkan -oic acid
• HCOOH methanoic acid
• CH3COOH ethanoic acid
• CH3CH2COOH propanoic acid
• CH3CH2CH2COOH butanoic acid

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Naming Carboxylic Acids

• Identify longest chain that contains the carbon
  of the carboxyl group
• Replace the e of the alkane name with oic acid
• Number the parent with carboxyl carbon as 1
• Name and number the substituents as usual
• Is called carboxy if it is a substituent
• CH3
• CH3 CHCH2 COOH
• IUPAC 3-methylbutanoic acid

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Naming Carboxylic Acids

• If multiple carboxyl groups are present, 1 at
  each end, then it is named by retaining the e of
  the alkane name followed by dioic acid
• Note that both carboxyl groups must be in the
  parent and the location numbers need not be noted
• The parent for the aromatic carboxylic acid is
  benzoic acid the carbon containing the carboxyl
  group is 1
• Number and name substituents in the usual
  manner

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Learning Check CA1

• Give IUPAC and common names
• A. CH3COOH
• CH3
• B. CH3CHCOOH

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Solution CA 1

• A. CH3COOH
• ethanoic acid
• CH3
• B. CH3CHCOOH
• 2-methylpropanoic acid

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Physical Properties

• Very polar functional group
• Very high melting and boiling points
• Due to formation of a dimer since each molecule
  forms 2 hydrogen bonds

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Solubility
O ?? R COH
hydrophilic water loving
hydrophobic decreases water solubility

• As the size of the hydrocarbon chain
• increases relative to that of the
• carboxyl group, water solubility
• decreases

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Preparation of Carboxylic Acids

• Oxidation
• O more O
• Primary alcohol aldehyde
  carboxylic acid

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Acidity

• Carboxylic acids are weak acids
• CH3COOH H2O CH3COO H3O
• The form in which they exist in aqueous solution
• depends on pH
• Remember pH -log H

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Reaction with Bases

• Neutralized by strong bases
• CH3COOH NaOH CH3COO Na H2O
• stronger strong weaker
  weak
• acid base
  acid base

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Reverse Reaction

• CH3COO Na HCl CH3COOH
  NaCl
• carboxylic strong carboxylic
  salt
• acid salt acid acid

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Esters

• Ester - Carboxylic acid derivative where the
  hydroxyl (OH) is replaced with -OR
• Represented as COOR or CO2R

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Esters

• In an ester, the H in the carboxyl group is
  replaced with an alkyl group
• O
• ??
• CH3 CO CH3 or CH3COO CH3
• ester group

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Ester Preparation

• Fischer Esterification
• Reaction of a carboxylic acid and alcohol (or
  phenol) to produce an ester
• Requires the use of an acid catalyst (H2SO4)
• O
  O
• ?? H
  ??
• R COH HOR1
  R COR1 H2O

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Fischer Esterification

• O
• ?? H
• CH3 COH HOCH2CH3
• O
• ??
• CH3 COCH2CH3 H2O
• Try benzoic acid methanol!!!

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Naming Esters

• Name the alkyl from the alcohol O-
• Name the acid with the CO with ate
• acid alcohol
• O
• ?? methyl
• CH3 CO CH3
• Ethanoate methyl ethanoate

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Naming Esters

• 1.The name of the alcohol part is first followed
  by the name of the acid part as a separate word
• 2.The name of the alcohol (-OR) part is the alkyl
  name of the carbon chain
• 3.The name of the acid part comes from dropping
  the ic acid from the acid name and adding ate
• 4. Use the same method for naming salts but
  replace the positive ion name with the alkyl
  group

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Some Esters and Their Names

• Flavor/Odor
• Raspberries
• HCOOCH2CH(CH3)2
• Pineapples
• CH3CH2CH2 COOCH2CH3
• Pheromones
• CH3COOCH2CH2CH(CH3)2

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Learning Check CA 2

• Give the IUPAC name of the following compound,
  which is responsible for the flavor and odor of
  pears.
• O
• ??
• CH3 CO CH2CH2CH3

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Solution CA2

• O
• ?? propyl
• CH3 CO CH2CH2CH3
• propyl ethanoate

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Learning Check CA 3

• Draw the structure of the following compounds
• 3-bromobutanoic acid
• Ethyl propanoate

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Solution CA 3

• A. 3-bromobutanoic acid
• Br
• CH3CHCH2COOH
• B. Ethyl propanoate
• O
• ??
• CH3 CH2 COCH2CH3 or CH3CH2COOCH2CH3

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Cyclic Esters

• Lactones a cyclic ester

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Physical Properties of Esters

• Cannot H-bond to each other but can H-bond to
  water
• Boiling points are lower than alcohols and
  carboxylic acids of similar mass
• Low mass esters are soluble in water
• Solubility decreases as the carbon chain length
  increases

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Ester Hydrolysis

• Esters react with water and acid catalyst
• Splits the reactant into 2 products a carboxylic
  acid and an alcohol
• Reaction is slow w/o a catalyst
• O
• ?? H
• CH3 COCH2CH3 H2O
• O
• ??
• CH3 COH HOCH2CH3

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Hydrolysis

• O
  O
• ?? enzyme ??
• R CNHR1 H2O R COH NH2
  R1
• O R1
  O R1
• ??
  enzyme ??
• R CNR2 H2O R COH HNR2

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Ester Saponification

• Esters react with a base
• Splits the reactant into a carboxylic acid salt
  and an alcohol
• O
• ??
• CH3COCH2CH3 NaOH
• O
• ??
• CH3CO Na HOCH2CH3
• salt of carboxylic acid

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Esters in Plants

• Esters give flowers and fruits their pleasant
  fragrances and flavors.
• Central structure in all edible fats and oils.

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Learning Check CA4

• Write the equation for the reaction of propanoic
  acid and methanol in the presence of an acid
  catalyst.

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Solution CA4

• O
• ?? H
• CH3CH2COH HOCH3
• O
• ??
• CH3CH2COCH3 H2O

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Learning Check CA5

• What are the organic products when methyl
  ethanoate reacts with
• A. Water and an acid catalyst?
• B. NaOH?

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Solution CA5

• A.
• O
• ??
• CH3COH HOCH3
• O
• ??
• B. CH3CO Na HOCH3

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Acid Chlorides

• Acid Chloride derivative where the OH of the
  carboxyl group is replaced with Cl
• Are named by replacing oic acid of the
  carboxylic acid with oyl chloride

O ?? R C Cl
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Preparation of Acid Chlorides

• O O
• ?? PCl3 or SOCl2
  ??
• CH3 COH CH3
  CCl
• Carboxylic Acid

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Acid Chloride Hydrolysis

• O
• ?? H-OH
• CH3 CCl
• O
• ??
• CH3 COH HCl
• Carboxylic acid

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Acid Anhydrides

• O O
• ?? ??
• R COC R1
• Acid anhydride derivative where the OH of the
  carboxyl group is replaced with -OCOR
• 2 carbonyl groups bonded to the same
• oxygen

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Naming Anhydrides

• 1. If symmetrical (same R groups), name the acid
  (minus the word acid) and add anhydride
• 2. If different groups, name the individual
  parent carboxylic acids in alphabetical order
  (minus the word acid) and add anhydride
• O O
• ?? ??
• CH3 COC CH3
• ethanoic anhydride

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Learning Check 5

• Give the IUPAC name of the following
• compounds
• O O
• ?? ??
• C6H5 COC C6H5
• O O
• ?? ??
• C6H5 COC CH2 CH2 CH3

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Solution 5

• O O
• ?? ??
• C6H5 COC C6H5
• Hexanoic anhydride
• O O
• ?? ??
• C6H5 COC CH2 CH2 CH3
• Hexanoic Propanoic Anhydride

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Preparation of Anhydrides

• O O
• ?? ??
• CH3 CCl CH3 CO-
• Acid Chloride Carboxylate ion
• O O
• ?? ?? Cl-
• CH3 CO C CH3

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Reactions with Water

• Anhydrides react readily in water to form 2
  molecules of carboxylic acids
• O O
• ?? ??
• CH3 COC CH3 H2 O
• O O
  
• ?? ??
• CH3 COH HO CCH3

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Reactions with Alcohols

• Anhydrides react w/ alcohols to give an ester
• and a carboxylic acid
• O O
• ?? ??
• CH3 COC CH3 CH3 CH2 OH
• O
  O
• ?? ??
• CH3 COCH2 CH3 HO CCH3