Green chemistry is one of the most important areas of science for creating more sustainable ways of living, this experiment will support learners to get involved

This session should take 90 minutes.

Equipment

Apparatus

  • Eye protection
  • Disposable gloves
  • Safety glasses
  • Aprons 
  • Glass vials
  • Orbital shaker

Chemicals

  • Hydroxypropyl methyl cellulose mol wt 90,000 
  • Phthalate buffer, 0.1 N, pH 4 
  • Phosphate buffer, 0.1 N, pH 7
  • Benzonitrile
  • Benzamide, and samples of polymers made from natural products (polylactides etc)
  • Cellulase 13L enzyme solution 
  • Nitrile Hydratse cells

Health, safety and technical notes

  • Read our standard health and safety guidance here.
  • Wear eye protection if desired.
  • Perform a risk assessment.
  • This experiment should be performed in a fume cupboard.

Procedure

The hydrolysis of polypropylene

  1. Shake 200 mg of polypropylene chips with 2 cm3 of pH 7 buffer solution in a glass vial at room temperature.
  2. Note your observations.

The hydrolysis of a cellulose derivative

  1. Take two 4 cm3 vials containing 100 mg of hydroxypropylmethyl cellulose (molecular weight ~90,000)
  2. Add 2 cm3 of 0.1N phthalate buffer (pH4) to each vial. Cap the vials and shake them vigorously to disperse the solid.
  3. To one vial only add 100 µl of Biocatalysts cellulase 13L enzyme solution.
  4. Cap the vial and shake both vials on the orbital shaker at 500 rpm at room temperature for one hour. Note the difference between the two vials. What has happened to the vial containing enzyme?
  5. Measure the pH of the vial containing the enzyme and compare to the starting buffer.

The hydrolysis of biodegradable poly l-lactide

  1. Shake 200 mg of poly l-lactide, 2 cm3 of pH 5 buffer solution and 50 µl of esterase enzyme in a glass vial at room temperature. Note your observations.
  2. Repeat the above experiment without the enzyme. Note your observations.

The hydrolysis of benzonitrile – mimic of the Mitsubishi Acrylamide Process

  1. Take two 4 cm3 vials, one containing 3 mg of freeze dried cells.
  2. Add 1 cm3 of 0.1N phosphate buffer (pH7) to each vial.
  3. Cap the vial and shake it to disperse the cells.
  4. Add 100 µl of benzonitrile to each vial.
  5. Cap the vials and shake both vials on the orbital shaker at 500 rpm at room temperature for one hour. Note what has happened to the reactions.
  6. Measure the pH of the reactions and compare these to the starting buffer.

Notes

The activity takes one and a half hours.

The experiments are designed to reach a good visual end point in 40-45 minutes.

If time is limited the experiments need to be set up and allowed to run during the talk. 

  1. Arrival
  2. Greeting and assign experiments (5 minutes)
  3. Introduction to experiments (5 minutes)
  4. Set-up (15–20 minutes)
  5. Talk and questions (45 minutes)
  6. Experimental results and wrap up (15 minutes)

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