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Author: Subject: reduction with HI without phosphorous
goldberg
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[*] posted on 8-8-2020 at 00:38
reduction with HI without phosphorous


Purerly theoretical question: i have read about mechanism of HI/P reduction(please skip bad assotiations with this reaction, no i do not want to have legal problems) and phosphorous is used to convert iodine back to hydroidic acid.

So would be possible to use other reductant to convert I2 back to HI?
Ascorbic acid can convert I2 to HI, the question is if it would not be destroyed in harsh conditions of this reaction before regeneration of HI.

Or SO2 in form of pyrosulfate? Thiosulfate would decompose liberating SO2 and elemental sulphur which is not good.
H2S can convert iodine to hydroiodic acid, it is toxic and more difficult to handle than phosphorous but we can consider it theoretically.
Or maybe electrochemical conversion of I2 back do HI?
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clearly_not_atara
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[*] posted on 8-8-2020 at 09:33


Ascorbate could work in principle, but it will undergo SN2 OH->I substitution.

Cyclohexadiene or reductic acid might work. Ti2O3 seems like a possibility. I doubt there are any "simple" answers.




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Chemi Pharma
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[*] posted on 8-8-2020 at 11:48


Quote: Originally posted by goldberg  
Purerly theoretical question: i have read about mechanism of HI/P reduction(please skip bad assotiations with this reaction, no i do not want to have legal problems) and phosphorous is used to convert iodine back to hydroidic acid.

So would be possible to use other reductant to convert I2 back to HI?
Ascorbic acid can convert I2 to HI, the question is if it would not be destroyed in harsh conditions of this reaction before regeneration of HI.

Or SO2 in form of pyrosulfate? Thiosulfate would decompose liberating SO2 and elemental sulphur which is not good.
H2S can convert iodine to hydroiodic acid, it is toxic and more difficult to handle than phosphorous but we can consider it theoretically.
Or maybe electrochemical conversion of I2 back do HI?


Quite simple. Just use I2 and hypophosphorous acid. The last can be synthesized in situ reacting sodium hypophosphite with 37% HCl.

@ChemPlayer has two videos about making hypophosphorous acid and about using it with I2 to reduce mandelic acid to phenyl acetic acid.

This method can be applied to every "OH" reduction group instead using I2/RP, with decrease of the necessary reaction time, better yields and no RP to filter after the reaction has been done.

See here, at Bit Chute site:

https://www.bitchute.com/video/Tgj8r6paMc5E/

https://www.bitchute.com/video/CncZs5QKGh5M/
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JJay
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[*] posted on 8-8-2020 at 19:22


I remember reading something about using aluminum a while back on another forum... as I recall, it worked but produced unsatisfactory yields.

Does HI reduction work on secondary alcohols generally or mainly just on benzylic alcohols?
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draculic acid69
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[*] posted on 9-8-2020 at 01:19


Try bubbling so2 into water and using that instead of hypophosphorus acid.
I know sodium metabisulfite turn halogen into the acids but then u have a sodium
ion in your rxn mix. I'm guessing that if u just used so2+water it will work the same
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[*] posted on 9-8-2020 at 16:45


Why not continue adding HI to the reaction, while distilling out water. Iodine will accumulate; I don't know if that will cause problems. Probably depends on substrate.

Might be possible to Hydrogenate a hot solution containing HI, utilizing a catalyst like Tungsten Carbide, as Platinum catalysts might be dissolved by hot I2 in solution. Though heck, I'm not even sure Tungsten Carbide would hold up to Hot HI and I2. 10 Atmospheres?

And, I'm thinking Benzylic Alcohols are probably easier to reduce. On account of the stability of that carbonium ion.
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