Nuclear Magnetic Resonance

1
Iodochlorination of Styrene 1 Hexene
Characterization by NMR
2
Aim

• Do iodochlorination reaction with styrene and 1
  hexene.
• Characterize the products with NMR spectroscopy.

3
Introduction

• Todays experiment is an example of
  regioselective reaction.

4
Regioselective Rn

• Reagents and alkenes can be classified as either
  symmetric or unsymmetric with respect to
  addiction reaction.
• If a reagent or an alkene is symmetric, only one
  addition product is possible.
• If both the reagent and alkene are unsymmetric,
  two products are possible.

5
Regioselective Rn

• Styrene and 1-Hexene are unsymmetric alkene.
• Potassium dichloroiodate is also unsymmetric.
• You may get two products and these are called
  regioisomer.

6
Regioselective

• If a reaction of this type gives only one of the
  two possible regioisomer, it is said to
  regiospecific.
• If it gives mainly one product, its said to be
  regioselective.

7
Regiospecific-example
8
Regioselective-example
9
Procedure

• Take 5 mL of CH2Cl2 and add 0.12 mL of styrene in
  a clean and dry conical flask.
• Add 0.33 g of potassium dichloroiodate to the
  mixture.
• Swirl it for 15 minutes.
• Transfer into a separatory funnel.
• Wash it with 3 mL of aqueous 5 potassium
  sulfate solution until decolorization occur.

10
Procedure

• Then wash it with 3 mL of water.
• Take a fresh, dry glass funnel add 0.5 g of
  magnesium sulfate and filter the bottom layer
  through a plug of cotton.
• Wash the cotton wool with 3 mL more CH2Cl2.
• Evaporate the CH2Cl2 on a steam bath.

11
Procedure

• Recrystallize residue in hexane( 5 mL).
• Calculate the of yield.
• Do the same experiment with 1 Hexene.
• Record the NMR spectrum.
• Lab manual has the chemical shift values for the
  possible products.

12
Notes

• Do not spill the potassium dichloroiodate on
  benches, balances.
• Use non-metal spatulas to handle potassium
  dichloroiodate
• Use CH2Cl2 carefully.
• Do not forget to add boiling chips to the
  solution when you use steam bath.