Synthesis of Luminol

Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed.

• Before you get started, put on a lab coat, splash-proof safety glasses, and nitrile gloves. The chemicals that you will use are hazardous, so both solutions must be prepared and handled in a fume hood.
• Prepare 10 mL of a 10% by volume solution of hydrazine in water. Measure 8.4 mL of deionized water and add it to a 30-mL beaker.
• Measure 1.6 mL of hydrazine hydrate and pour it into the beaker for a total volume of 10 mL. Stir the hydrazine solution with a glass rod until it is well mixed. Note: Hydrazine is flammable, toxic, and explosive.
• Pour the solution into a 20-mL glass bottle. Cap it and label it with the solution's name and concentration. Store the hydrazine hydrate and the hydrazine solution in a cabinet for flammables.
• Prepare 20 mL of 2.8 to 3 M aqueous NaOH. Note: NaOH is highly corrosive. Avoid skin contact.
• Measure 2.2 to 2.4 g of solid NaOH and add it to a 50-mL beaker. Add 20 mL of deionized water and stir the mixture on a stir plate until the NaOH has completely dissolved.
• Pour the solution into a 20-mL glass bottle and close it with a lid. Label the bottle with the solution's name and approximate concentration. Store the NaOH pellets and solution in the appropriate cabinets.
• Lastly, clean your glassware following your usual procedures.

• Before you set up the main lab, reserve a separate room that you can make as dark as possible.
• Prepare a container for fluorescein waste and ensure that a glass waste container is available.
• Set out a 10% sodium hypochlorite (bleach) solution and a 1 M sodium carbonate solution in the waste hood.
• Fill a wash bottle with deionized water and place it in the same hood. Confirm that there are paper towels and a test tube brush by each sink in the main lab.
• Bring containers of 3-nitrophthalic acid, anhydrous sodium dithionite, solid potassium hydroxide, and fluorescein to the balance area.
• Confirm that there are enough laboratory wipes, spatulas, and weighing boats for the class.
• Set triethylene glycol, the hydrazine solution, the NaOH solution, glacial acetic acid, and dimethyl sulfoxide in a central hood. Place a 1-mL graduated pipette and a pipette controller designated for hydrazine in the same hood.
• Put Pasteur pipettes, filter papers, scissors, and plastic paraffin film in a central area.
• Set out the following glassware and equipment at each student lab station (we suggest that students work in pairs):

  1    Stirring hotplate

  1    Bunsen burner with tubing

  2    Lab stands

  3    Clamps

  1    Pair of flask tongs

  4    10-mL graduated cylinders

  1    50-mL graduated cylinder

  3    25-mL Erlenmeyer flasks

  1    250-mL filter flask

  1    50-mL beaker

  2    250-mL beakers

  1    400-mL beaker

  1    600-mL beaker

  2    25-mL test tubes

  2    Büchner funnels

  1    Long glass stirring rod

  1    Medium stir bar

  2    Thermometers

  2    Spatulas

  6    Boiling chips

  1    Medium filter adapter

  1    Test tube stopper

  1    Small flask stopper

  1    Pair of tweezers

  1    Fire striker or lighter

  1    Roll of laboratory tape or labels

  2    Pipette bulbs

  1    Pen