GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
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Coloration / Staining
HELLO!
I want a comprehensive list of all color changing solutions for identification of various compounds. It would help if these were biologically
friendly!
1. In the presence of air Indoxyl oxidizes and dimerizes to form indigo. [Colorless -> indigo]
2. Iodine and potassium permanganate staining are common for TLC. Stains heavily conjugated molecules. Toxic.
3. Curcumin from turmeric is pH sensitive. It goes from yellow to orange at ph >8.4
4. Phenolphthalein - yay. Suspected carcinogen.
There are a ton of pH sensitive dyes, I'm more interested in dyes that are easily oxidized in air or when hydrated/dehydrated change color. In
presence of some media become colored, etc.
#1 is my favorite so far.
The purpose of this is to simply have a colored reminder of timing that I can put on my arm 
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GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
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5. Methylene blue is observed to oxidize very slowly in air, and quicker with a metal catalysts like iron. It also oxidizes carbohydrates in the
presence of iron and pyrophosphate (ferro-pyrophosphate). This end product is a dark black or brown. 17% oxidation takes place on the order of 10-24
hours.
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gutter_ca
Hazard to Others
Posts: 173
Registered: 7-6-2010
Location: California
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Mood: Bored at work!
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Sigh
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GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
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it isn't really, i have my reasons but unfortunately if I shared them I'd be murdered.
Please help me in surviving!
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neptunium
National Hazard
Posts: 987
Registered: 12-12-2011
Location: between Uranium and Plutonium
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wow!!! murdered?? really? where are you ? in Iran??
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Panache
International Hazard
Posts: 1290
Registered: 18-10-2007
Member Is Offline
Mood: Instead of being my deliverance, she had a resemblance to a Kat named Frankenstein
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sorry please explain (that was a pauline hansen reference for anyone not living in australia ten years ago)
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GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
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I just want a dye that is either oxidized in air and changes color or is photo-sensitive to visible light and changes color.
Look up zubbles - that is a good example.
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GreenD
National Hazard
Posts: 623
Registered: 30-3-2011
Member Is Offline
Mood: Not really high anymore
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Wait a minute this doesn't make sense:
For instance, an amino group conjugated to an azo group (chromophore) via, for instance, a benzene ring, will form an aminoazo
chromogen. The conjugated amino auxochrome shifts the absorption band of the azo group to longer wavelengths and
increases the intensity of the absorption band. However, judicious placement of a sulfonic acid group to an amino azo chromogen is
not conjugated, however, the electron withdrawing effect causes a shift of absorption to longer wavelengths.
Isn't an amino group electron donating? Or are both of them electron withdrawing?
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