Sciencemadness Discussion Board

Chemistry of nitrite and ascorbate

Non_radioactive_elements_ - 24-8-2023 at 17:30

When I had been trying to synthesize some analogues of Roussin's salts with different metal ligands, I perceived that a reaction occurs between nitrite and ascorbate. I dissolved a spatula of sodium nitrite in 1-2 mL of water to make a concentrated a solution and just after I put a spatula of ascorbic acid. Instantaneously a redox reaction takes place with liberation of NO, but nothing so curious can be notable. However, when I added 1 mL of NaOH 12 M, the solution quickly changed to yellow, orange and finally an intense red. Boiling the solution, the color intensifies and seems like a blood-red. Can someone help me to understand the explanation for this reaction?

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averageaussie - 24-8-2023 at 20:06

Could be PH dependant - the reaction might not take place at neutral ph. try adding less NaOH, and see if the reaction proceeds slower. you could also add acid during the colour change, to see if it stops.

Boffis - 25-8-2023 at 13:53

Have you checked out some of the existing threads on sorbic acid?

Try this one: http://www.sciencemadness.org/talk/viewthread.php?tid=155475...

This thread contains some answers to your questions.

Diachrynic - 26-8-2023 at 00:51

Quote: Originally posted by Boffis  
Have you checked out some of the existing threads on sorbic acid?
I couldn't find a mention of ascorbic acid (vitamin c) in that thread.

But the thread Energetic precipitate from the reaction of ascorbic acid/Cu(II) and sodium nitrite could be relevant.

I was able to dig up this reaction in the literature:
P. L. Sarma, "A new analytical reaction for ascorbic acid" Microchemical Journal 1963, 7(3), 272–276. https://doi.org/10.1016/0026-265X(63)90050-X
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Fructose and other dihydroxyketones react with the alkali hydroxides, producing a red color which is similar to the color produced by potassium hydroxide with the reaction products of ascorbic acid and a nitrite. It may be that treatment of ascorbic acid with potassium nitrite followed by potassium hydroxide brings about a decarboxylation of the ascorbic acid to a dihydroxyketone which then reacts with the potassium hydroxide to give the red color characteristic of such compounds. Bromine water or sodium hypochlorite could be used in place of a nitrite, but hydrogen peroxide, nitrates, chlorates, and persulfates were useless or unsatisfactory.


They don't give a structure or anything else concrete, however. Worse, they call it "intensely colored resins of an unknown constitution".

Boffis - 31-8-2023 at 13:28

@Diachrynic, sorry about that. For some reason I read sorbic acid instead of ascorbic acid.