Author Topic: Debunking the Hg2Cl2 myth  (Read 1907 times)

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Antibody2

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Debunking the Hg2Cl2 myth
« on: September 07, 2001, 05:14:00 PM »
Ok bees, this bee has read and heard alot from other bees regarding the difficulties associated with amalgamating or activating Al with Hg2Cl2. Indeeed until very recently antibody would have agreed, it did indeed take awhile to properly amalgamate with this chem. Further it often took so long to amalgamate that the foil was so crunched up or compressed by stirring that there were many areas that did not amalgamate at all.

However in a recent conversation with Blue (a bee from the past) he/she was adamant that amalgamation could take place with Hg2Cl2 in minutes.

proceedure:
add appropriate amount of Hg2Cl2 to a 50% aqueous methanolic solution. Bring to mild reflux for 3-4 minutes, then add Al remove heat and stir for additional 5 minutes, after which time a vigourous effervecence will be visible, solvent will become gray with dissolved Al, and amalgamation is complete. Decant solution, rinse once with whatever rxn solvent is to be used, decant and add reaction solvent and reagents. Allow reagents to react work-up according to preference.

the work of 10-15 minutes 8) .

"All those memories lost like rain..."

unnilhexium

  • Guest
Re: Debunking the Hg2Cl2 myth
« Reply #1 on: November 04, 2001, 04:18:00 PM »
Great post.  This post could spur some interesting dreams.
In a 50% "methanolic solution,"is there any possibility
of methyl mercury being formed?  Exactly what role does
the methanol play?  Does it just happens to be
an excellent solvent for the hg2cl2, where as water is
not?

Thanks

If you're not part of the problem, you're part of the solution.

Osmium

  • Guest
Re: Debunking the Hg2Cl2 myth
« Reply #2 on: November 04, 2001, 07:11:00 PM »
AB2!

Don't complicate matters more than necessary. Simply add the Hg salt to the solvent already containing the Al, stir for a few minutes and then add the other reactands. Never had one failure that way.

terbium

  • Guest
Re: Debunking the Hg2Cl2 myth
« Reply #3 on: November 05, 2001, 03:07:00 AM »
Simply add the Hg salt to the solvent already containing the Al, stir for a few minutes and then add the other reactands. Never had one failure that way.
With mercuric chloride this would be true. Are you saying that this is also true with mercurous chloride? You have actually used calomel to prepare aluminum amalgam? The problem with calomel is that it is just so very insoluble.

Chromic

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Re: Debunking the Hg2Cl2 myth
« Reply #4 on: November 05, 2001, 06:03:00 AM »
I've found it best to add the mercuric chloride to the methanol and then add the aluminum. YMMV.

Osmium

  • Guest
Re: Debunking the Hg2Cl2 myth
« Reply #5 on: November 05, 2001, 01:56:00 PM »
> With mercuric chloride this would be true. Are you saying
> that this is also true with mercurous chloride?

Yes.

> You have actually used calomel to prepare aluminum
> amalgam?

Yes. I used whatever Hg salt happened to be around, and used Hg2Cl2 at least two times.

> The problem with calomel is that it is just so very
> insoluble.

Well, let's assume that it has a solubility of 0.1%, meaning 1g/L. That's good enough for amalgamation.

terbium

  • Guest
Re: Debunking the Hg2Cl2 myth
« Reply #6 on: November 06, 2001, 04:20:00 AM »
Well, let's assume that it has a solubility of 0.1%, meaning 1g/L. That's good enough for amalgamation.
Yes, if it was soluble to this degree that would certainly be sufficient. The problem is that it is not, the solubility in water is 3 orders of magnitude less than this - 0.0002% (2mg/L); and even less in methanol.

Osmium

  • Guest
Re: Debunking the Hg2Cl2 myth
« Reply #7 on: November 06, 2001, 12:47:00 PM »
Can you back up that number? Find it hard to believe that its solubility is that small.

Anyway, it still worked.

Antibody2

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Re: Debunking the Hg2Cl2 myth
« Reply #8 on: November 06, 2001, 09:40:00 PM »
the only reason i even posted this is cuz my chem supplier fucked up and sent the wrong stuff, it is in fact the mercurous salt i was refering too. i did a few quik tests after one failed amalgamation with it to make sure there was not repeat failures. the one posted above gets you too the track in a few minutes. Doing as Os suggests simply takes longer, i'm impatient :)  is all.

I actually kept that MeOH/H20 solution and kept using it for different amalgamations until all the Hg had been depleted.

"All those memories lost like rain..."

terbium

  • Guest
Re: Debunking the Hg2Cl2 myth
« Reply #9 on: November 07, 2001, 03:30:00 AM »
Can you back up that number? Find it hard to believe that its solubility is that small.
That number is from the Merck Index, Eighth Edition, 1968. Listing for mercurous chloride. Maybe Stonium could cut and paste the info from a more recent Merck Index.