Chemoluminescence of the Luminol-NaOH-DMSO System

Original Posting in German: http://illumina-chemie.de/chemolumineszenz-des-luminol-dmso-...

Equipment:
beaker glass (small)
2 x volumetric flasks (25 ml)
pipette (10 ml)
Gilson pipette (1000 µl)
balance


Chemicals:

DMSO (Dimethylsulfoxide) CAS: 67-68-5
Luminol CAS: 521-31-3
NaOH CAS: 1310-73-2
fluorescein sodium salt CAS: 518-47-8

Attention: DMSO can act as a carrier for substances with a molecular weight up to 3000 unit, directly through the skin

Preparation:

Put about 0.75 g NaOH in 2 ml of water and dissolve it. Fill the two volumetric flasks with 10 ml DMSO and add in one of these flask a small amount of fluorescein sodium salt plus about 50 mg of luminol in every flask.
Now add 200 µl of the NaOH-Solution and shake the closed flasks. After while you will see a nice glow.

Explanation:

Sodium hydroxide reacts in this DMSO-Water solution* with luminol to the dianion of luminol, which reacts with the oxygen in the flask and makes a endo-peroxide, which degrades under the emission of light.

*= The paper "A new, long-lasting luminol chemiluminescent cold light" J. Chem. Educ., 1970, 47 (7), 519 (DOI see Literature) says, that rising water content (over 5%) will quench the reaction and if the concentration is over 20%, the reaction will be completely inhibited. If you adjust the luminol concentration to 10 mg/ml the oxygen in the flask will be consumed very quickly and only pure nitrogen will be left over.

Here is the mechanism:


Source (Accessed: 4. February 2013)

Waste-Management:

In Germany there are places where you can get rid of chemical hazardous waste, without charge. So investigate your local possibilities, for this kind of waste (Solvents, non halogenated)


Pictures:

The Chemicals:


Sodium hydroxide Solution:


10 ml of DMSO:


Weighted Luminol:


Luminol-DMSO-Solution:


Glow of pure Luminol:


Glow of Sodium-Fluorescein-Luminol-DMSO-NaOH-Solution:


Comparison of both solutions:


Literature-Sources:
Experiment derivated from
A new, long-lasting luminol chemiluminescent cold light

Secondary source (in German):
Chemolumineszenz des Luminols
(Accessed 4. February 2013)
Mainpage with experiments

Remarks
At a scout camp I made a bottle with about 400 ml DMSO Solution and used very approximately amounts (few gram NaOH, a spatula tip of luminol and fluorescein sodium and about 8 ml of water) and it worked, too. There was a delay of 15 seconds.....but after shaking the whole bottle was glowing.
IMPORTANT: Use a good PTFE-Septa-Cap, because the kids will put the bottle anywhere...and I mean really ANYWHERE.

Bj68



[Edited on 4-2-2013 by BJ68]