Mr Cole Chemistry

Organic Synthesis Pathways Questions 2

  • Questions
  • Tab2 Title 2
  1. The following molecule can be produced in either a two-step pathway or a three-step pathway.
    1. Fill in the missing molecules in the two pathways
    2. State one disadvantage to pathway one.
    3. State one disadvantage to pathway two.
    4. Outline the mechanism in the first step of pathway one.
  2. The following molecule can be produced in  a two three step mechanism. The first step involves a chloromethane as the reactant, and the third step is an oxidation reaction.
    1. Fill in the missing molecules.
    2. Outline the mechanism for the first reaction in the pathway.
    3. Name the catalyst used in reaction 2 and show how it behaves as a catalyst.
    4. State the reactants and conditions for reaction 3.
    5.  The first three steps of the mechanism for reaction 3 are outlined below, missing the curly arrows and lone pairs. Fill them in to complete the three steps.
  3. The following synthesis pathway is missing two intermediate molecules.
    1. Draw the missing molecules.
    2. State the reagents and conditions for step 1.
    3. State the reagents and conditions for step 4.
    4. Describe the mechanism for reaction four (outline it with words not diagrams)
  4. The following pathway is used to make a precursor for pharmaceuticals. There is one step in this pathway that you are no expected to know, which is the conversion of carboxylic acid to acyl chloride using phosphorus chloride.
    1. Fill in the missing molecules.
    2. State the mechanism or type of reaction for steps 1a, 1b, 2a, 2b and d.
    3. State the reagents and conditions for steps 1a, 1b, 2a, 2b and d.
    4. State the name of each of the molecules.
  5. The following pathway is used to make aspirin.
    1. Fill in the missing molecules.
    2. State the names of the molecules in the first two boxes.
    3. State the reagents and conditions required for reaction 1.
    4. State the reagents and conditions required for reaction 2.
  1. The following molecule can be produced in either a two-step pathway or a three-step pathway.
    1. Fill in the missing molecules in the two pathways
    2. State one disadvantage to pathway one.
      Further nucleophilic substitutions can occur, resulting in the formation of secondary or tertiary amines.
      The chlorine can be added to carbon 1 or carbon 2 in the first step. In fact, you are more likely to get the chlorine added to carbon 2 than carbon 1. This would result in 2-propylamine.
    3. State one disadvantage to pathway two.
      HCN is toxic.
    4. Outline the mechanism in the first step of pathway one.
  2. The following molecule can be produced in  a two three step mechanism. The first step involves a chloromethane as the reactant, and the third step is an oxidation reaction.
    1. Fill in the missing molecules.
    2. Outline the mechanism for the first reaction in the pathway.
    3. Name the catalyst used in reaction 2 and show how it behaves as a catalyst.
      AlCl3 is a catalyst. AlCl3 first reacts with HCOCl forming HCO+ and AlCl4–.
      AlCl3 + HCOCl –> HCO+ + AlCl4–
      Later, the AlCl4– is regenerated back into the AlCl3 by reacting with the H+ produced.
      AlCl4– + H+ –> AlCl3 + HCl
    4. State the reactants and conditions for reaction 3.
      Acidified potassium dichromate, heat under reflux
    5.  The first three steps of the mechanism for reaction 3 are outlined below, missing the curly arrows and lone pairs. Fill them in to complete the three steps.
  3. The following synthesis pathway is missing two intermediate molecules.
    1. Draw the missing molecules.
    2. State the reagents and conditions for step 1.
      No other reagents. Concentrated sulfuric acid catalyst.
    3. State the reagents and conditions for step 4.
      NaCN and dilute sulfuric acid.
    4. Describe the mechanism for reaction four (outline it with words not diagrams)
      The lone pair on the cyanide ion carbon attacks the partially positive carbon of the carbonyl.
      This forms a bond between the two carbon atoms, and causes the pi bond on the carbonyl to break with the electrons moving onto the oxygen.
      The oxygen now has a negative charge. The lone pair on the oxygen attacks a hydrogen ion, forming a bond between the oxygen and the hydrogen, producing the hydroxy group.
  4. The following pathway is used to make a precursor for pharmaceuticals. There is one step in this pathway that you are no expected to know, which is the conversion of carboxylic acid to acyl chloride using phosphorus chloride.
    1. Fill in the missing molecules.
    2. State the mechanism or type of reaction for steps 1a, 1b, 2a, 1b and d.
      1a: electrophilic substitution
      1b: Oxidation
      2a: Electrophilic substitution
      2b: Reduction
      d: Condensation
    3. State the reagents and conditions for steps 1a, 1b, 2a, 2b and d.
      1a: methanoyl chloride, AlCl3 catalyst, heat under reflux
      1b: Acidified potassium dichromate, heat under reflux
      2a: Concentrated nitric acid and concentrated sulfuric acid
      2b: HCl and Sn catalyst (or Fe catalyst)
      d: The two reactants
    4. State the name of each of the molecules.
  5. The following pathway is used to make aspirin.
    1. Fill in the missing molecules.
    2. State the names of the molecules in the first two boxes.
    3. State the reagents and conditions required for reaction 1.
      Ethanoic acid, conc sulfuric acid catalyst
    4. State the reagents and conditions required for reaction 2.
      Methanoyl chloride, AlCl3 catalyst, heat under reflux
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