Chemistry Alchemist
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Ascorbic Acid -> Oxalic Acid
So there was a previous thread about decomposition of ascorbic acid and Sriraman said
Quote: Originally posted by Sriraman  | The path way of decomposition of Ascorbic acid is Ascorbic acid to Dehydroascorbic acid to 2,5 Diketogulonic acid and then to oxalic acid and
L-threonic acid. you can guess which gives yellow colour-possibly 2,5 diketogulonic acid due to its two ketonic functions
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Now this post was made in 2004 so its pretty old, and it doesn't explain much, there was one more post after that and then the thread died. Now i made
a post a while ago about Oxalic acid from rhubarb and other threads you can make oxalic acid with other methods, but none really discussed this
method... so i thought maybe discuss it here as it sounds pretty simple... but then again... when is organic chemistry ever simple?
Ascorbic Acid is readily valuable from health stores as Vitamin C but most of the time it isn't 100% Ascorbic Acid, my tablets that my family get has
Sodium Ascorbate also in it so i could probably dissolve the whole tablet into water and acidify the water to turn Sodium Ascorbate into ascorbic acid
and a sodium salt... and then cool the solution to crystallize out the acid.
Now im a noob to how to do organic chemistry so i don't know how things take place but i think i figured out the equation to what is needed.
C<sub>6</sub>H<sub>8</sub>O<sub>6</sub> =
C<sub>6</sub>H<sub>6</sub>O<sub>6</sub> + H<sub>2</sub>
The first equation is a reduction, KMnO4 can be used to reduce it to Dehydroascorbic acid and Hydrogen Gas but how would u then separate the
contaminates from the chemicals we want?
C<sub>6</sub>H<sub>6</sub>O<sub>6</sub> + H<sub>2</sub>O +
C<sub>6</sub>H<sub>8</sub>O<sub>7</sub>
Now because the first reaction will contain water it will most likely go straight to the second reaction which hydrates it to 2,5 diketogulonic acid
which would then maybe follow on to the next reaction as 2,5 diketogulonic acid reacts with the water to form Oxalic Acid and L-threonic acid
5 C<sub>7</sub>H<sub>8</sub>O<sub>7</sub> + 7 H<sub>2</sub>O = 3
H<sub>2</sub>C<sub>2</sub>O<sub>4</sub> + 6
C<sub>4</sub>H<sub>8</sub>O<sub>5</sub>
So would the reaction play out on its own? id really like to know more about this 
[Edited on 26-11-2011 by Chemistry Alchemist]
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theflickkk
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Reduction with KMnO4? Isn't KMnO4 an oxidizing agent?
I would think that KMnO4 would oxidize the hydroxyl functional groups of ascorbic acid.
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Chemistry Alchemist
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thats what i thought but in the thread they said that KMnO4 and a few other chemicals were used and it reduced the ascorbic acid to 2,5 diketogulonic
acid (the purple solution of the permanganate turned to a yellow solution of 2,5 diketogulonic acid)
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chemoleo
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Thread Moved
26-11-2011 at 15:36 |
Chemistry Alchemist
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has anyone got a detailed synthesis of this reaction?
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