Sciencemadness Discussion Board


Polverone - 4-2-2004 at 22:47

There's a well-known <A HREF="">synthesis</A> of guanidine nitrate from <A HREF="">calcium cyanamide</A> and ammonium nitrate. Disadvantages: possibly hazardous, and depending on what part of the world you live in, calcium cyanamide and/or ammonium nitrate may not be readily available.

From discussion on the E&W Forum and <A HREF=" 50&s1=4,535,185.WKU.&OS=PN/4,535,185&RS=PN/4,535,185">US Patent 4535185</A> I learned that guanidine nitrate could be produced with a silica gel catalyst, urea, and ammonium nitrate. However, VasiaPupkin provided personal testimony that this method can be hazardous (leading to explosions).

A few weeks ago, I read an interesting article in the Journal of Applied Chemistry of the USSR, and remembered enough of it for a few hours to e-mail the following to myself:

"Best results found from heating 1:1:1 weight ratios of NH4NO3, silica gel,
and urea to 190 degrees for 2 hours. Best results with large surface area,
large pore size silica gel catalysts. Ammonium carbonate, phosphate,
sulfate did not work, but chloride and bromide did (with reduced yields).

Result from some 1959 or 1960 volume of Journal of Applied Chem USSR"

I want to say that yields with ammonium chloride and bromide were in the 25% range. That's not spectacular, but all of the materials are very inexpensive, no special equipment is needed, and there is no danger of explosion as with other methods. Obviously, substitution will result in guanidine salts of hydrochloric or hydrobromic rather than nitric acid.

chemoleo - 5-2-2004 at 17:18

Although it's very interesting (it really is), I happen to have GdnHCl in bulk. Apart from making GdnHNO3, what other uses are there? There got to be many!

guaguanco - 5-2-2004 at 22:46

You can make a lot of heterocyclic chemicals with guanidine:
guanidine + 2,4 pentanedione -> 1-amino 3,5- dimethyl pyrimidine
guanidine + ethyl acetoacetate -> 1-amino 3-hydroxy 5-methyl pyrimidine
guanidine + bromoacetone -> 1-amino 3-methyl imidazole

etc etc

safer method for guanidine nitrate

Rosco Bodine - 22-3-2007 at 15:21

Here's a method which proceeds at mild temperatures
in the presence of water and also provides high yield .

Attachment: US2230827 Guanidine Nitrate via Cyanamide and NH4NO3 in H2O.pdf (328kB)
This file has been downloaded 2074 times

DrP - 23-3-2007 at 02:30

I wrote to and phoned a chinease company and they sent me a sample of natural guanidine powder in the post. Basically - it was a bag of powdered sea bird shit! :D

Sobrero - 23-3-2007 at 11:45

Natural grade indeed :D

@Rosco Bodine: that's the synthesis I have followed to make my batch of guanidine nitrate. High yields indeed and very safe compared to other routes and very OTC for me (I bought technical (56%) calcium cyanamide and ammonium nitrate as fertilizers in a nearby horticulture/agriculture centre).

urea can also be added to reduce the reaction temperature

Rosco Bodine - 23-3-2007 at 15:06

An improvement was claimed by a subsequent patent
US2431301 ( attached ) which relates to the same
reaction of Calcium Cyanamide with Ammonium Nitrate
to produce Guanidine Nitrate , using an addition of urea
in ~15% proportion to the Ammonium Nitrate for the purpose
of lowering its melting point , as an alternative to the use of
water for that purpose of obtaining a more easily fusible mixture . From the more anhydrous mixture a higher purity
product is supposed to be obtained in higher yield .

From what I have read about these calcium cyanamide processes , these reactions proceed well even using the
commercial fertilizer grade material which may be only perhaps half actual calcium cyanamide , so these processes
should proceed even better using a high purity calcium cyanamide as would be obtained from pyrolysis of calcium acid cyanurate .

These cyanamide , guanidine related threads are important
in their relevance also to the tetrazole thread .

Attachment: US2431301 Guanidine Nitrate via Calcium Cyanamide and Ammonium Nitrate - Urea melt.pdf (354kB)
This file has been downloaded 1549 times

Axt - 21-6-2007 at 05:53

Historical paper on the extraction of guanine from guano and oxidation to guanidine. Guano is available here as a fertiliser. Its in german so I'm not real sure what details they go into and I assume 'guano' comes in various grades so the practicality of this is questionable. Though is interesting.

Attachment: guano to guanidine.pdf (599kB)
This file has been downloaded 1504 times

Organikum - 22-6-2007 at 01:39

Excerpt/translation from the paper posted by Axt, part one, the extraction of guanine from guano:

Preparation of guanine:
He says this is easily done by the method described by Unger, cooking guano with milk of lime.
But he found it advantageous to modify the procedure in the following way:
Guano is dispersed in water, milk of lime is added in portions and this is brought to a boil and the resulting brown solution is filtered through a pointed bag of cloth. This repeated as long the liquid takes on color.
This removes large amounts of ammonia, acids and other compounds (including urea nitrate and a counpound related to xanthine). Guanine and ureic acid are the residue.
This residue is then repeatedly extracted with boiling sodium carbonate solution as long as addition of HCl produces a fallout.
To the joined extracts first sodium actetate and then HCl is added until strongly acidic. Guanine and urea precipitate out of solution. The residue is washed with water and treated with slightly diluted boiling HCl and the ureic acid is filtered out. The filtered solution is boiled down for crystallisation to yield guanine which still contains considerable amounts of ureic acid.
From this guanidin is separated by means of boiling hot diluted ammoniawater, it is then dissolved in boiling hot concentrated nitric acid waht destroys the last ureic acid.
On cooling pure yellowish crystals of guanine nitrate precipitate.
Guanine is prepared form the nitrate by treatment with concentrated ammonia water, the product is only slightly yellow and used as is in the following experiments.

Oxidation comes when I have time again.


[Edited on 22-6-2007 by Organikum]

Guanidine from Urea

AndersHoveland - 20-1-2012 at 21:10

By heating urea, ammonium chloride, and aluminum sulfate together with ammonia under pressure, guanidine can be obtained. The reaction products are boiled with an ammonium hydroxide solution to precipitate out the aluminum hydroxide. The remaining clear filtrate contains guanidine hydrochloride, ammonium sulfate, unreacted urea, and unreacted ammonium chloride. Using equimolar ammounts of NH4Cl and urea, with one third of a mole aluminum sulfate for every mole of urea, heated to 275degC, and subjected to 6.8 atmospheres of pressure, the yield of guanidine (relative to initial urea) was 28% after 30 minutes, and 34% after two hours. Using excess NH4Cl increased the yields further.

clearly_not_atara - 14-2-2020 at 20:26

A thought: since it seems like non-coordinating anions work better for the urea method, maybe ammonium hexachlorostannate is worth a look? This salt precipitates readily from water and is non-hygroscopic.

I think the "ammonia under pressure" method sounds interesting but maybe not so easy to set up?

clearly_not_atara - 26-6-2020 at 08:33

Found one:

A mixture of 300 g. of urea and 1140 g. of ammonium sulfamate was fusedin an oil bath to provide a clear melt at a temperature of about 90 C. Thereafter, the temperature was Bradually raised to 225 C. with no appreciable amount of decomposition, i. e., there was no evolution of gas. At the aforementioned 225", C. a rapid exothermic reaction began to occur so that despite removal of the heat source the temperature of the reaction mixture rose to 245 C. After about 30 minutes the reaction mixture had set up to a solid mass and the reaction was apparently over. The solid was then cooled, ground and leached with water to obtain 388 g. of guandine sulfate of 70% of theory.