Synthesis of Triptycene

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Synthesis of Triptycene
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Goals

• in situ Synthesis of Chemically Highly Reactive
  BENZYNE.
• Prepare Triptycene using benzyne.
• Characterization by
• 1. Melting Point
• 2. 13C NMR Spectroscopy

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Introduction

• Bicyclic Compound
• Chemical compound containing two ring structures.

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Synthesis

• These kind of bicyclic compounds can be prepared
  by CYCLOADDITION METHOD OR DIELS ALDER
  REACTION.

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Synthesis

• There are two kinds of reactants involved in the
  reaction in a cyclo addition reaction.
• 1. Diene.
• 2. Dieneophile.

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Diene

• Dienes are the organic compounds which has
  conjugate double bonds (alternate position).

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Dieneophile

• The dieneophile can be an alkene or alkyne and
  may bear groups such as -CHO, -COR, -COOH, -NO2,
  -CN, -SO2R etc. It can have one or two such
  Electron Withdrawing Groups.

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Mechanism
Cyclic Transition State
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Triptycene

• Triptycene is a novel bicyclic compound.
• Unique bicyclic compound because its molecular
  weight and the melting point is same.

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Procedure

• Take a 100 mL Round bottom flask and add
• 1. 2.0 gram of anthracene
• 2. 2.0 mL of isoamyl nitrite
• 3. 20 mL of 1, 2 dimethoxyethane.
• Fit a reflux condenser.
• Keep a hot plate under the RB flask.

FOR MORE INFO...
Experiments in Organic Chemistry, 1998 by M.
Stoner, Department of Chemistry, University of
South Dakota.
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Procedure

• Keep a small funnel on the top of the condenser.
• Moisten a filter paper with 1, 2
  dimethoxyethane and insert into the funnel.
• Weigh 2.6 gram of anthranilic acid and transfer
  into the filter paper which is resting on the
  funnel.

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Procedure

• Heat the reaction mixture till you get gentle
  boiling (Do not over heat).
• Measure 20 mL of 1, 2 dimethoxyethane and add
  in small portion to anthranilic acid.
• Why????
• So that leaching of the anthranilic acid into
  the reaction mixture will be efficient.

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Procedure

• Once all anthranilic acid has leached down, stop
  heating and cool the reaction mixture to room
  temperature.
• Add 2.0 mL of isoamyl nitrite (through top of the
  condenser).
• Take another 2.6 gram of anthranilic acid and
  transfer into the funnel and do the leaching
  again with 20 mL of fresh 1, 2 dimethoxyethane.

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Procedure

• Once you done the second leaching reflux the
  reaction mixture for 10 more minutes.
• Cool down (wait for atleast 10 minutes) the
  reaction mixture.
• Add 10 mL of 95 ethanol and 35 mL of 10
  sodium hydroxide with stirring.
• Cool the reaction mixture using ice bath.

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Procedure

• You will be getting nice solid.
• Filter them using Buchner funnel and wash the
  solid with cold methanol water (41) mixture.
• Dry the solid.

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Characterization

• Find the melting point of the compound.
• Do the 13C NMR spectroscopy of the product.

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Precautions

• Do not circulate cold water when you do
  refluxion.
• Why?
• If you pass cold water the vapors of 1, 2
  dimethoxyethane will be staying down and there
  wont be leaching!

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Precautions

• Apply appropriate heating.
• Over Heating
• Over heating sends the vapor of 1, 2
  dimethoxyethane out of the condenser and you will
  be getting very, very less product.
• Slow Heating
• Slow heating keeps the vapor of 1, 2
  dimethoxyethane down and leaching will not be
  efficient.

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Precautions

• This reaction product is explosive when there is
  no solvent. So do not heat RB to dry.
• Always wear safety glass.

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Precautions

• We will be using flammable solvents so no
  FLAMES in lab today

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Notes

• Work four people in a group.
• Its a very, very simple reaction, do not mess up
  by
• 1. not following the procedure.
• 2. not using the correct chemicals in right
  amount.