Alchemist
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Unknown compound from urea and sulfur?
Hello all,
Really hope I have NOT missed this some where, but I have searched this sight under Urea, Sulfur, Thiourea, Thiocyanates, and etc.. Also I have
searched the net in the same way and can't not find a single thing!
That is, what is the compound formed when Urea is gently melted then sulfur added ( about 150deg). I did this with about twice the amount of urea than
sulfur (by weight). I then let it cool, chipped it out of my crucible. Next I put it into a beaker and cover it with a just over enough water to cover
the powder (about 5 grams) (a very light brownish shade). It dissolved completely after heating to a boil. The boiling did give off some sulfur
dioxide. This is as far as I have gotten so far.
Any help would really be appreciated. Thanks, The Alchemist.....
P.S., What is the name of, or is there even such a program you can put two compounds in and it will predict the result compound or compounds?
<sub>Edit by Nicodem: Made the thread tittle descriptive of the topic discussed.</sub>
[Edited on 14/3/2008 by Nicodem]
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MagicJigPipe
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According to this patent
http://www.freepatentsonline.com/4330319.html
Melting urea and sulfur together only produces a homogenous mixture of the two.
Although it is strange that it dissolved completely.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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Nicodem
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I have no idea what you got, but you would have to get at least the sulfur back after dissolving in water, unless it all got consumed. Was there any
H2S smell?
| Quote: | Originally posted by Alchemist
P.S., What is the name of, or is there even such a program you can put two compounds in and it will predict the result compound or compounds?
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It is called library, but it does not always give good results. In such case one is left with only one alternative, by using a program called LAB,
which is a very messy and dirty process consuming a lot of time and chemicals.
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PHILOU Zrealone
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If S reacted, what seems the case because no elemental S was found after dilution, it would either reduce or oxydise. The amount of possible products
and inter-reaction makes it difficult to figure exacly what happened!
1°)S oxydised to SO2 ... so the oxygen must have been taken out of the C=O; then I can imagine that the coupled reaction could be:
-S linked to C (C=S) making thiourea
NH2-CO-NH2 +S --> NH2-CS-NH2 + SO2
-S dehydrogenating NH2 to make H2S and cyanamide (NH2-C#N) (# stands for tripple bond)
NH2-CO-NH2 + S --> NH2-C#N + SO2 + H2S
-a mix of the two
2°)S reduced to H2S; so the only oxydation possible is on the nitrogen atom
so coupled reaction could be:
-S bonded to N
NH2-CO-NH2 + S --> NH2-CO-N=S + H2S
-S bridging
NH2-CO-NH2 + S --> NH2-CO-NH-S-H --> NH2-CO-NH-S-NH-CO-NH2 + H2S + NH2-CO-NH-S-S-NH-CO-NH2
-N bridging
NH2-CO-NH2 + S --> NH2-CO-NH-NH-CO-NH2 + H2S --> NH2-CO-N=N-CO-NH2 + H2S
In both cases the SO2 or H2S might be bond to the mild basic NH2 group.
All products can react further with the urea, thiourea or cyanamide to make biurea or melamine related compounds.
A good way to be sure a reaction has occured would be to perform a molecular mass determination via cryoscopy or ebulioscopy, but the resulting
molecular mass would be the average of the molecular mass of the remaining reactants and of the products...
[Edited on 13-3-2008 by PHILOU Zrealone]
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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not_important
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MagicJigPipe is right, sulfur coated urea is a common fertiliser. The sulfur is heated to 140 C or so, the urea prills preheated to 70 or 80 C, the
two mixed, then coated with wax, and then cooled.
Might try repeated it with carefully weighed amounts. One time nix the leach solution with base to grab oxidised sulfur - sulfites and sulfates;
another run treat with strong acid like HCl to capture ammonia. Weight the solid products after evaporation to get an idea how much oxidised sulfur
and combined nitrogen (ammonia) there is.
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woelen
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Also, a good thing might be to try the experiment in a test tube, flooded with CO2. This excluded the possibility of oxidation by oxygen from air. A
test tube already is a lot more controlled than a crucible, which is hard to keep out of contact with air.
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kmno4
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Urea cyanurate manufacture
United States Patent 4018769
(...)
Sulfur does not participate in the reaction and does not combine with the reactants, products or byproducts.
(...)
EXAMPLE 1
Urea (435 grams) and sulfur (200 grams flowers of sulfur were added to a two-liter, three-neck flask provided with a 260° C. thermometer, a
mechanical stirrer and water-cooled condenser. The stirrer was operated continuously. The materials were gradually heated to a temperature of 190° C.
over a period of 20 minutes. Both the urea and sulfur were molten at this temperature. The sulfur, being less dense, formed a separate phase, a
substantial part of which floated on top of the molten urea. The temperature was then gradually increased to 200° C. and held at that level for 10
minutes. At 195° C. the urea phase turned from its previous clear appearance to an opaque, milky color below the overlying sulfur layer and a white
solid precipitate was evident.
(...)
I will try to repeat this procedure if I have time. Generally I do not belive in patents 
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Alchemist
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Hello ,
Thanks all for the replies. I am at work now, but will try some more experiments around 3:00 today.
woelen, I will try a test tube with CO2, because yes the crucible had a wide mouth and I did NOT use a cover.
Not_important, I will try your idea. On my first run I used approximately 5g of Urea and 2g of Sulfur. Do you think I should stick to this or change
the amounts?
PHILOU, I would like to do cryoscopy or ebulioscopy but do NOT have the means.
What I was really hoping to find was a easy way to Thiourea, but now I have gotten interested in finding anything.
Does anyone know if there are any TRUE compounds of Urea and SULFUR or for that matter UREA and HYDROGEN SULFIDE, UREA and SULFIDES or SULFITES,
etc..
Thanks again, the Alchemist.....
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kmno4
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1g of sulfur and 2g of urea melted together at 140° C.
Above 140° C my heating bath (high boiling hydrocarbons) started smoking too much and I could not reach higher temperature. Besides urea
itself starts to decompose above its m.p.
[Edited on 14-3-2008 by kmno4]
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Alchemist
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Hello all,
Well it is NOT Urea Cyanurate, I read the patent and it said Sulfur is only a cataylist. This IS a compound! The Sulfur DOES combine with the Urea!
What, I still do NOT know?
Yesterday I did do the experiment again in a test tube flushed with CO2. Have not had time to to do more experiments on it though. It's waiting with
cotton in the tube for now.
I did try adding to old batch some NH3 in one test tube and HCL in another test tube . No color change at all, and only a very faint oder of SO2 with
the HCL test tube.. These where still a pretty watered down solution so maybe I need to concentrate. Also I tried a several drops of Ferric Chloride.
Only VERY slightly darker than Ferric Chloride itself.
Kmno4, my Urea + Sulfur melt is a VERY dark brown (almost black). I am using a very low bunsen burner flame direct (no oil bath) and a infra-red
thermometer to measure temperature. Will try to get some pictures.
Well thats it for now. More after the week end. The Alchemist.....
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Nicodem
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You might consider doing the experiment more properly under controlled conditions (oil bath, measuring the temperature with a real thermometer, known
quantities, etc.). You should know that urea equilibrates to ammonium cyanate at temperature above its melting point and that this can further react
(for example, if it reacts with urea you get biuret and ammonia). So you would get all kind of products anyway - not just from a putative reaction
with sulfur. Yet, if the literature says no reaction occurs, and Kmno4's test also, then I must also advise you to verify that what you have is really
pure sulfur and urea.
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kmno4
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All I have wanted to say, Nicodem has just said.
I have repeated metling urea+sulfur but up to 170° C.
Observations: up tp ~140° C melted urea is colorless, starting from ~150° C it is becoming blue (colloidal sulfur or impurities).
Small gas bubbles appear on the walls. Up to 170° C nothing special happens: urea is still blue ( a little darker but clear as temp. goes up), more
bubbels (strong smell of NH3) also at the surface of melted S.
I have had to stop heating at about 170° C because sulfur has been getting very viscous (polymerisation). At this point I have taken a picture. In a
bath I used this time canola oil (not used beer  )
* I put the mixture from recent experiment into water and boiled it, almost to dryness. I still had urea(+urea in water) and unchanged sulfur.
During all experiments there was no H2S or SO2 smell.
[Edited on 14-3-2008 by kmno4]
[Edited on 14-3-2008 by kmno4]
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Alchemist
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Hello to all,
Not much new to report, still DO NOT KNOW what I have, but I am going to take Nicodem and Kmno4 suggestions and just make some Biuret, Cyanate, and
maybe Cyanuric Acid then melt Sulfur with each of these and do some more testing.
Thanks for all the help, the Alchemist.....
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not_important
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What i the source of the urea and sulfur you are using? Are they lab grade, or agricultural grade?
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Alchemist
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Hello,
Not_important, lab grade Sulfur, but agricultural grade Urea!
The Alchemist.....
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