Sciencemadness Discussion Board

Hypochlorous acid Preparation?

GrayGhost - 18-5-2015 at 14:46

Someone know hypochlorous acid preparation according to procedure Higuchi and Hasegawa? I can´t find in the web this methode.

Please.

byko3y - 18-5-2015 at 15:11

As far as I can see, they use a neutral aqueous N-chlorosuccinimide to obtain the hypochlorous acid. http://pubs.acs.org/doi/abs/10.1021/j100887a015
Anyway, there's tonns of ways to prepare the hypochlorous acid, like neutralization of NaOCl/Ca(OCl)2 with a weak acid, dissolution of trichloroisocyanuric acid, sodium dichloroisocyanurate and chloramine T in water.

GrayGhost - 18-5-2015 at 15:18

Quote: Originally posted by byko3y  
As far as I can see, they use a neutral aqueous N-chlorosuccinimide to obtain the hypochlorous acid. http://pubs.acs.org/doi/abs/10.1021/j100887a015
Anyway, there's tonns of ways to prepare the hypochlorous acid, like neutralization of NaOCl/Ca(OCl)2 with a weak acid, dissolution of trichloroisocyanuric acid, sodium dichloroisocyanurate and chloramine T in water.


Thank you byko3y , by info. I prepare hypochlorous with ClONa acidified with ClH, mesure Ph with litmus paper by is decolorizated .

blogfast25 - 18-5-2015 at 16:04

Quote: Originally posted by GrayGhost  
Someone know hypochlorous acid preparation according to procedure Higuchi and Hasegawa? I can´t find in the web this methode.

Please.


HClO can't be 'prepared' or at least not isolated. It's highly unstable. In that paper it only 'exists' as an intermediate.



[Edited on 19-5-2015 by blogfast25]

GrayGhost - 18-5-2015 at 16:19

Quote: Originally posted by blogfast25  
Quote: Originally posted by GrayGhost  
Someone know hypochlorous acid preparation according to procedure Higuchi and Hasegawa? I can´t find in the web this methode.

Please.


HClO can't be 'prepared' or at least not isolated. It's highly unstable. In that paper it only 'exists' as an intermediate.

I No need isolate the acid, only in solution, the point is,in a paper the acid oxidate l-phenylalanine to phenilacetonitrile 100% conversion. I make the experiment and obtained few drop of liquid yelow fog with smell floral. ( excuseme im speak spanish).

I tempted isolate the liquid inmiscible in water solution of hipochlorous acid with trichloroethilene (one solvent in hand) , evaporate and nothing.:(
[Edited on 19-5-2015 by blogfast25]

blogfast25 - 18-5-2015 at 16:24

GrayGhost:

Acidifying hypochlorite with HCl produces chlorine:

HClO + HCl → H<sub>2</sub>O + Cl<sub>2</sub>

Your litmus paper was most likely bleached to uselessness.



[Edited on 19-5-2015 by blogfast25]

GrayGhost - 18-5-2015 at 16:32

Quote: Originally posted by blogfast25  
GrayGhost:

Acidifying hypochlorite with HCl produces chlorine:

HClO + HCl → H<sub>2</sub>O + Cl<sub>2</sub>

Your litmus paper was most likely bleached to uselessness.



[Edited on 19-5-2015 by blogfast25]


Yes and no. If ClH is in excess you obtain Cl2 gas im experimented that, but if adition of ClH is controled between Ph 3 and 6.5 approx you obtain the specie Hypochlorous acid mostly.

Start with sodium hypochlorite commercial in my case 4.75g/liter and acidificate slowly and monitoring with litmus paper.

Boffis - 18-5-2015 at 17:01

@Blogfast

I am not normally one to argue but....

Check out these patents they are all about the preparation of "hypochlorous acid". The second is via solvent extraction'
US 2240344
US 3578400
US 3718598

I must admit I was under the impression that hypochlorous acid existed in equilibrium with chlorine and water and alkaline conditions favored the higher hypochlorite ion concentration but these patents seem to indicate otherwise. Perhaps in the case of the solvent extaction the hypochlorite ions form some kind of stabilized association compound with the ketone.

Attachment: Preparation of hypochlorous acid solution US 2240344.pdf (514kB)
This file has been downloaded 588 times

Attachment: Preparation of Hypochlorous acid by solvent extraction US 3578400.pdf (347kB)
This file has been downloaded 677 times

Attachment: Preparation of Hypochlorous acid US 3718598.pdf (326kB)
This file has been downloaded 481 times

blogfast25 - 18-5-2015 at 17:09

Quote: Originally posted by Boffis  
@Blogfast

I am not normally one to argue but....

Check out these patents they are all about the preparation of "hypochlorous acid". The second is via solvent extraction'
US 2240344
US 3578400
US 3718598




No, no, you MUST argue. :)

I'll have a look a this later tomorrow.

blogfast25 - 19-5-2015 at 08:44

I’m not hugely impressed by these patents.

From one example:

<i>MEK, 642 g; HClO (claimed), 0.816 g</i>. That’s barely 0.13 %

And no characterisation of the product to be seen either.

GrayGhost - 19-5-2015 at 14:10

Quote: Originally posted by blogfast25  
I’m not hugely impressed by these patents.

From one example:

<i>MEK, 642 g; HClO (claimed), 0.816 g</i>. That’s barely 0.13 %

And no characterisation of the product to be seen either.


The patents lie, the scientifics papers exagerate with yields, all people lie,f.....ck.

Litmus paper don´t work because decolorize, two way, tritation or pH meter, no need the pure acid only pH 3 or 3.5.

chornedsnorkack - 21-5-2015 at 08:55

Quote: Originally posted by blogfast25  


HClO can't be 'prepared' or at least not isolated. It's highly unstable.


The bigger problem is that it happens to be an immiscible composition.

Pumukli - 21-5-2015 at 10:19

Accidentally I came across a hypochlorous acid preparation recipe today. It can be found in Hilgetag-Martini-Weygand Preparative Organic chemistry, page 137, can be found on the Net.

Here it goes:


"The following procedure may be used for preparing an aproximately 20% hypochlorous acid solution (HOCl) from chlorine hydrate and HgO:

Chlorine is passed to saturation into water that is stirred vigorously and cooled in ice-salt freezing mixture. The precipitated chlorine hydrate is filtered off and mixed, with stirring, with sufficient HgO (about 3/4 its weight) to give an aqueous solution and remove the smell of chlorine. This solution is filtered and distilled in room temperature and 12 mm.
The distillate, which contains up to 20% of HOCl, is kept in the dark in the frozen state, it is stable for several months at -10 C."


Then it can be used to prepare chlorohydrines by addition to olefins at 10 C, at least the book goes on with such preparations.