Sciencemadness Discussion Board

Lab work (orgo lab): Oxidizing leucomethylene blue?

dennisfrancisblewettiii - 14-9-2011 at 04:43

I have a part of the lab that asks how I might about about analyzing a colorless fraction of leucomethylene blue after I elute methylene blue with solvents (i'm eluting both methyl orange and methylene blue). The solvents I am choosing are hexane and toulene. I expect that it will elute, but I'm not sure what to oxidize it with. I suspect a lot of the solution will look colorless, so I won't be able to know when it has eluted.

In the lab, I believe there will be these solutions and compounds, water, methanol, ethanol, 1-propanol, acetone, toulene, hexane, and Na2SO4.

Can I use any of these as oxidizing agents?
How should I go about oxidizing the leucomethylene blue?

Thanks.

- Genecks

[Edited on 14-9-2011 by Genecks]

Ozone - 14-9-2011 at 05:32

We use it (reduced with glucose) as an oxygen indicator in anaerobic fermentations. In protic media, oxygen (from the air) readily oxidizes it to give the blue species. See:

http://www.udel.edu/pchem/C446/Experiments/exp7.pdf

dennisfrancisblewettiii - 14-9-2011 at 05:44

Are you saying that being in air long enough should give it its color back?

I'm thinking maybe air is the oxidizing agent and all I have to do is shake the test tube or stir the elute in a beaker, but I'm not sure that is the case, because it seems that leucomethylene blue needs some kind of chemical to change the bonds. I could be wrong, though.

I read about the blue bottle experiment, and it seems to have other chemicals inside of it other than the methylene blue; thus, I beleive that for my experiment, I'll need to add some other chemical and shake it in an environment with air.

[Edited on 14-9-2011 by Genecks]