Sciencemadness Discussion Board

Hydroiodic acid from Vitamin C !

Sulaiman217 - 1-5-2021 at 06:55

we know the conventional way of making HI using red P and iodine, but i have never seen any procedure such as this.
https://youtu.be/DmM8ikmL0os
this guy is using ascorbic acid and elemental iodine to make HI!
is it possible ? i spend days in google looking for any patent or any article describing this procedure but never found one!

Fery - 1-5-2021 at 08:09

Why not using KI + H3PO4 ?
https://www.youtube.com/watch?v=ix8T1YQjn4E
Or H2S + I2 ? (disadvantage H2S poisonous and necessity to filter out precipitated S)
HI is quite sensitive to air oxygen, it darkens fast.

njl - 1-5-2021 at 14:44

HI is probably formed since ascorbic acid is a reasonably good reducing agent but I don't think this is really a great way to go about it. Also the video says that the byproduct is "benzene hexol" but I think the oxidation of ascorbic acid yields the creatively named dehydroascorbic acid.

Sulaiman217 - 2-5-2021 at 17:29

Quote: Originally posted by Fery  
Why not using KI + H3PO4 ?
https://www.youtube.com/watch?v=ix8T1YQjn4E
Or H2S + I2 ? (disadvantage H2S poisonous and necessity to filter out precipitated S)
HI is quite sensitive to air oxygen, it darkens fast.

But in terms of purity, is ascorbic acid method same as other methods?

Sulaiman217 - 2-5-2021 at 17:32

Quote: Originally posted by njl  
HI is probably formed since ascorbic acid is a reasonably good reducing agent but I don't think this is really a great way to go about it. Also the video says that the byproduct is "benzene hexol" but I think the oxidation of ascorbic acid yields the creatively named dehydroascorbic acid.


And do you think a simple distillation would remove side products ?

njl - 2-5-2021 at 17:43

Side products as well as unreacted starting materials. The ascorbic acid method is probably worse in terms of purity, H3PO4 can be made very pure and dry plus distillation from phosphoric acid is advantageous since the acid is not very volatile. Considering this could be easily tested on a sub gram scale though it would be worth pursuing if you're interested.

unionised - 3-5-2021 at 13:47

Doesn't HI react with OH groups, and aren't dehydroascorbic- and ascorbic- acid full of OH groups?

njl - 3-5-2021 at 14:02

Yes and yes, but at least at room temperature the equilibrium would be towards HI.

Texium - 4-5-2021 at 07:14

Quote: Originally posted by njl  
Also the video says that the byproduct is "benzene hexol" but I think the oxidation of ascorbic acid yields the creatively named dehydroascorbic acid.
Sounds like they subtracted "H2" from the formula for ascorbic acid, found benzenehexol, and ran with it. Dehydroascorbic acid and benzenehexol are both C6H6O6... but a rearrangement of one to the other would be very far-fetched.