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Author: Subject: Need help w/ Sulfamic synthesis
DeAdFX
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[*] posted on 28-7-2008 at 12:05
Need help w/ Sulfamic synthesis


Yesterday I attempted to synthesize Sulfamic acid from old rooto drain cleaner and fertilizer grade Urea in a ~3:1 mol ratio acid/urea. This ratio was determined from this patent http://www.google.com/patents?id=btE5AAAAEBAJ&printsec=a... as it was the only one I could find concerning synth from concentrated Sulfuric acid and not H2SO4/SO3. The addition of urea to sulfuric acid was slow (1 mol over 1 hour) as to avoid over heating.

Anywho I let this mix sit out overnight and I see no precipitate. The sulfuric acid looks the same as it did yesterday. How do I extract the Sulfamic acid?
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kilowatt
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[*] posted on 28-7-2008 at 14:53


Not sure about this, but I should think sulfamic acid could be made by the reaction of ammonia with chlorosulfonic acid, with the release of HCl. Chlorosulfonic acid its self is formed by the addition of SO3 and HCl. This would be similar to the formation of sulfamide but with only one group substituted.

[Edited on 28-7-2008 by kilowatt]




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kclo4
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[*] posted on 28-7-2008 at 15:03


I can't find any other patents on making sulfamic acid from urea and Sulfuric acid, with out using SO3. Probably a good reason why they use SO3. Are you sure that your reaction actually forms sulfamic acid in decent quantities? What is the reaction anyways? I think it will form diurea sulfate, and/or urea bisulfate but I really couldn't say :P
Best of luck with making sulfamic acid! It is a rather useful chemical! :D
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DeAdFX
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[*] posted on 28-7-2008 at 15:14


@ kilowatt.. Chlorosulfonic acid sounds far out of my league in terms of chemicals/lab skills.

@Kclo4 SO3 method is used because 2 mols of sulfamic acid and one mol of CO2 is made per mol of urea as opposed to the sulfuric method which generates 1 mol sulfamic + 1 mol ammonium sulfate. I thought I remember seeing a lot more patents concerning the sulfuric/urea method.

Anywho I have a hunch you are correct about the urea sulfate and or bisulfate. I think I will dink around on google patents for awhile in the mean time.
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kclo4
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[*] posted on 28-7-2008 at 15:25


Hmm if it also produces ammonium sulfate, I wonder if you could make sulfamic acid from Cyanuric acid.

"The current industrial route to CYA entails the thermal decomposition of urea, with release of ammonia. The conversion commences at approximately 175 °C:[1]

3 H2N-CO-NH2 → [C(O)NH]3 + 3 NH3 "

I can't find anything on the reaction of conc. Sulfuric acid on Cyanuric acid but you'd think they would react in one way or another. I just don't know if they would produce anything that is wanted. Since your reaction produces Ammonium sulfate, you are basically taking out an ammonia molecule I guess, which happens when you heat urea.

Heh well just an idea!
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crazyboy
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[*] posted on 28-7-2008 at 15:53


Are you doing this for fun or because you need sulfamic acid? It is sold in one pound containers as an acid based cleaner for getting rid of hard water stains and lime build-up, I should know I spent several hours cleaning out the fountain with it.

I think its 99% pure.


If not try chilling the solution to get it to crystallize out.




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DeAdFX
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[*] posted on 28-7-2008 at 16:14


Yes I this is a for "fun project". I am also doing the synthesis because my sulfuric acid has degraded quiet a bit and it would be a waste just to use it for making sulfate salts. 2nd off I haven't seen any economical sources of it around the hardware stores and the like.
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kclo4
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[*] posted on 28-7-2008 at 16:24


Quote:
Originally posted by crazyboy
Are you doing this for fun or because you need sulfamic acid? It is sold in one pound containers as an acid based cleaner for getting rid of hard water stains and lime build-up, I should know I spent several hours cleaning out the fountain with it.

I think its 99% pure.


If not try chilling the solution to get it to crystallize out.


Where do you get it and what is the brand of the cleaner?
I have needed it in the past for experiments I wanted to do, but I could never find it.
Sure I could order it offline, but that's not at all as nice as getting a cheaper, just as good version at a store w/o shipping costs.

What would heating the mixture do?
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DeAdFX
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[*] posted on 28-7-2008 at 16:35


hmm.. I will try cooling the mixture first to see if anything precipitates and then I will try heating it if cooling fails. Sigh I was kinda hoping this would be somewhat straightforward :grumble:.


EDIT: hmmm jack shit appears to be happenign with the cooling... I will try heating acid/urea very soon

[Edited on 28-7-2008 by DeAdFX]
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crazyboy
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[*] posted on 28-7-2008 at 17:24


This is the exact brand I have:


I'm pretty sure it's in the tile section near grout and stuff.




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DeAdFX
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[*] posted on 28-7-2008 at 18:51


Hmm I let the sulfuric acid/urea mix sit in the ice bath a little longer. I ended up getting a thick sludge of crystals. I have no clue what they were but I ended heating the acid/urea up a bit (~70c). Nothing happened. Perhaps I have already made sulfamic acid? Sulfamic acid has a "low" solubility in water so I will see what happens when I dilute the acid/urea mix with a few hundred mils of water.

will update soonish..hopefully..

Ehh well great... adding water did jack shit. I think I will redo this synthesis and use calcium chloride to precipitate the sulfate ions and then boil down the solution so hopefully in theory I have sulfamic acid or something.

[Edited on 28-7-2008 by DeAdFX]

[Edited on 28-7-2008 by DeAdFX]
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not_important
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[*] posted on 28-7-2008 at 21:04


Sulfamic acid
Solubility in Water:
wt% g/100g H2O
@ 15.6°C 17 21
@ 20.0°C 18 22
@ 26.7°C 19 24
@ 37.8°C 22 28
@ 60.0°C 27 37
@ 71.1°C 30 43

hydrolyzes fairly rapidly in hot acidic solutions; a purification for it involved solution in hot water followed quickly by filtration and chilling in ice, losses were still appreciable.
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DJF90
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[*] posted on 28-7-2008 at 23:35


Try reducing the volume of the reaction mixture to half of its original amount (without taking the temperature too high, as not_important says it decomposes), and then chill. Crystals should form which should then be filtered using a buchner funnel and washed with some ice cold water.

[Edited on 29-7-2008 by DJF90]
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[*] posted on 29-7-2008 at 19:56


By all means buy if you can, unless you enjoy cooking precursors.
" Dry Lock Etch " is a 12 once jar of anhydrous sulfamic acid powder
available from Home Depo for just over 5 dollars. If you want a lot more . . .
www.capitolscientific.com/estylez_item.aspx?item=10102-50

.
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[*] posted on 30-7-2008 at 04:14


That patent specifically states that sulphamic acid is NOT formed.
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[*] posted on 30-7-2008 at 07:00


ha
HA
HA!
And here I thought that it was just my links that people didn't click on.
What can I say...Good preparation of nitrous if it works. They don't mention urea nitrate + H2SO4 -> nitrourea; boiling this in water to give N2O quantitatively, with no production of CO2.

I was wondering what was going on here, all the preparations of sulfamic acid that I've got jotted down involve acetoxime or hydroxylamine, with SO2.

[Edited on 30-7-2008 by S.C. Wack]
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[*] posted on 31-7-2008 at 04:42


Quote:

Best of luck with making sulfamic acid! It is a rather useful chemical!

Some of which would be?
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DeAdFX
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[*] posted on 31-7-2008 at 09:41


Quote:
Originally posted by ScienceSquirrel
That patent specifically states that sulphamic acid is NOT formed.


hmm how embarrassing. Well thank god this is the internet... Meh whatever I guess I will buy some and let this thread die quickly... well thanks for pointing my error out.

I guess if it works with oluem it won't work with conc sulfuric so much for that idea...

[Edited on 31-7-2008 by DeAdFX]
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