Calcium cyanurate ---> Cyanamide

Calcium cyanurate was made on a 1/3mol scale, using the procedure Rosco posted, however more water was necessary to dissolve all cyanuric acid.
The cyanurate was allowed to dry on a windowsill for 2 weeks, at which point it was easily powdered.

Thermal decomposition:
34.1g of the cyanurate was added to a 42.8g metal can with a tight fitting lid. The lid had a dozen or so 1mm holes punched in the lid. 34.1 g was only chosen as that was about the half filledmark on the can. Not sure where to get more of those cans, it was from zinc powder purchased at dye store in vancouver a few years ago.. It was essentially a very small metal paint can, 2" tall and 3" wide. Assuming the above reactions above are correct, after decomposition the can+cyanamide should weigh 59.1g. The can was wrapped in copper wire and a length attached to serve as a handle.
A good sized campfire was made, and the can put in at the bottom on the coals. It was left there for a couple hours occasionally shaking it around a bit, and adding more wood to the fire. Meanwhile hotdogs were roasted away from the can
When the flames of the fire were just right, you could see flames being emitted from the holes in the lid of the can(cyanuric acid burning off). At this point the can was a dull red. About 30 min later, flames from the can-hole were no longer noticable. A couple marshmallows were roasted, and then the fire maintained for 40min to 1h more. The fire was allowed to die down and the can removed and left to cool. When it was cool the can was noticibly degraded, the outer lay of metal on the can was flaking off. It weighed 55.2g. Metal flakes cracked off upon opening the can, and when the can was open a pure white powder was seen. Few bits of charcoal got in through the holes, but nothing sugnificant. The white powder was weighed and it weighed 11.4g. Slightly less than the 12.4g predicted, but that could be because cyanurate was damp.

Just based on the numbers it does look like cyanamide was produced, but I'll analyse it somehow, soon hopefully.

Calcium Cyanamide, all OTC


PS: Rosco, whats the referance for the cyanurate decomposing to cyamamide?

[Edited on 4-6-2007 by The_Davster]

Campfire Cyanamide YeeeeHaaa !
And it should be reagent purity if my guess is right .

Making some tetracene or something else interesting would
be the ideal test to see if you've got what you think you've got Probably could find some perfect tests for identifying this material .....over in the tetrazoles thread

I tried that brute force approach myself with the urea
and lime and charcoal mixture before figuring out
the cyanurate route would be better . What I used was a stainless steel chefs sized salt shaker with a threaded lid . It had one of those rotating perforated plates that covers up the sprinkling holes to keep the salt dry when you aren't using it . I just rotated the plate to cover the holes , knowing it would keep out any ashes , but wouldn't be pressure tight so it would vent fumes from inside . It was a cannister about 2 1/2 inches diameter by 4 inches tall , and I made a steel band to hold it to the end of about a six foot piece of tubular steel for a handle to stick it in the coals . After glowing in the fire at a nice orange heat for an hour , even the stainless didn't hold up . The metal was so embrittled that when I tried to unscrew the lid , the threads snapped off and left simply the unthreaded portion of the cannister . Nothing but a one time use even for a stainless container ....with that crude mixture anyway and as much heat as I was using .
It was hot enough to make graphite from the charcoal
in the mixture . And it was a black mess that I haven't even attempted to use that came out of that preliminary experiment .

Yeah , I had a feeling it might work a lot better with the
calcium acid cyanurate .....no side reactions and a pure white product that can only be one thing so long as it was heated hot enough long enough to complete the reaction . It should be a quantitative yield for cyanamide .

It might even work with no cyanic acid byproduct and
a better yield if the calcium normal cyanurate was used ,
that is if the Ca3 dicyanurate even exists IIRC it does exist and you would simply need to adjust the stoichiometry for the precursors to get the normal Ca3 dicyanurate instead of the Ca Hydrogen Cyanurate .

I was sort of hedging my bet by going with the Ca acid cyanurate because of betting there would be some residual moisture in the precursor ....which is poison
for the reaction ....but if there is some excess cyanic acid present ( as there is plenty excess using the Ca acid cyanurate precursor ) then it will be involved in a mutual decomposition with any trace water , and protect the
pyrolysis reaction by thoroughly dessicating and guaranteeing the purity of the calcium cyanate intermediate , preventing any water vapor from decomposing it before it can further decompose as planned from dry heat alone , to form the desired calcium cyanamide .

You could probably balance the reaction out so that
90% of the precursor is the normal Ca3 dicyanurate ,
and maybe have 10% of the Ca acid cyanurate present
as insurance against any residual moisture ....and still be just fine so long as the precursor is baked out good , and kept dry in storage before the pyrolysis .

I'll have to look up the relevant patent numbers again .

I thought I already posted the patent references in the other threads . I didn't have a patent specifically for
this method , but it was shown that calcium cyanurate
was an intermediate in the reactions described in patents
that describe the urea plus lime reactions . And it was mentioned in passing in the text of a couple of those patents also that it could be done this way using cyanurates or cyanates as higher intermediates , if
the purity of the end result was more important than
the economics of using cheaper urea . This is the
modification on the fertilizer grade process that you would
use to produce a reagent grade material for use in synthesis , rather than just making tons of something crude and impure to dump on a field as fertilizer .

Something like an empty propane cylinder might make a decent pyrolysis chamber . I removed the valve stem which is a shrader valve like the valve stem on a tire from an empty disposable propane cylinder , and drilled the hole out and tapped it for 1/4 " NPT , so a pipe nipple could screw into it and a long piece of larger water pipe could be used for a handle .
I screwed a short section of 1/4" pipe nipple into a reducer coupling and drilled vent holes in the sloped bell of the coupling so fumes exit in the fire and don't travel all the way through the handle which is capped off at the end .
The safety filler valve on the shoulder of the cylinder was also
drilled out and a stainless screw having a lengthwise groove
cut across the thread was screwed into that opening . The idea there was for a combination overpressure blowout plug and vent .

I haven't used this contraption yet , but it is about 3/4 of a liter capacity and thicker steel than a paint can , plus it can be rolled in the fire easily to tumble the contents . It is good to know the reaction product is loose powder and not some
rocklike clinker . So once the reaction is complete , it is like
pouring out an hourglass ....instead of time for a hammer and chisel to remove the product . BTW the calcium cyanamide is definitely air and moisture sensitive , so like calcium carbide , you should seal it up good for storage in a quality jar to keep atmospheric moisture away from it .

[Edited on 5-6-2007 by Rosco Bodine]

Quote:

Originally posted by Rosco Bodine Making some tetracene or something else interesting would be the ideal test to see if you've got what you think you've got Probably could find some perfect tests for identifying this material .....over in the tetrazoles thread

Tetrazoles later, I want purity data 98%, 99% or whatever it is. I may compare with commercial Ca-cyanamide from a supplier if I can scrounge some up at work.
Really, if you go the hydrazine route from here, you are a one pot reaction away from 5-ATZ But I have prefered transformations that avoid the hydrazine...but more work

Yes the powder is very fine, and if it is not, it is easily broken up. A few lumps remained after the heating, and I was worried they would be hard as well, but it is the most easily powdered material I have come across. It is of extremely low density.

Funny thing is, urea and charcoal would likely cost me more than for cyanuric, NaOH, and CaCl2, all but NaOH available at the hardware store in quantities not less than a kilo for under 10$.

I bought a ~1L paint can, could probably make over 500g at once in it, but a vessel that size would require bigger fire, and longer heating so the thin metal may fail. So it will probably go unused. a 100 or 150g(cyanurate) reaction would give me all the Ca-cyanamide I would ever need anyway. I should post a pic of the sorry state the little paint can is in. Need a new vessel now too

If you held a good steady red heat for an hour ,
then its a good bet you have pure cyanamide @ 99+%
purity . The only hitch would be that it needs to be anaerobic pyrolysis , because if too much air got to the glowing hot cyanamide , it would just oxidize to being burnt lime .

So you don't want too many vent holes , nor an open container ....but something that will trap the last bit of evolved CO2 inside as something of a protective atmosphere .

Looks like another good one for the upgraded Wiley
volumes

Possibly a simple furnace something like was mentioned in another thread using a couple of flower pots
to make a clamshell chamber , and a large Humboldt Meker type lab burner in an enlarged drain hole underneath would be sufficient for a crucible furnace that would get to the red to red orange heat that would be good . A clay piped triangle support for the crucible , maybe a fiberglass or rockwool wrap around the outside of the pots to help insulate the furnace a bit . Or just build a box furnace from marinite panels and some screws and angle iron as a sort of low range burner fired kiln .
A metal bucket lined with kaowool or some refractory would also do it . Any elementary furnace should get
hot enough .

Time for a calcium cyanurate cookout ?

IIRC the sodium salt is more stable in solution , whereas
the calcium salt is very subject to hydrolysis .

BTW....
Those above references seem to be woefully incomplete ......
as they are all totally lacking any reference whatsoever to
Rosco's good old country campfire / furnace / pottery kiln recipe for pure calcium cyanamide , another shake and bake grocery store precursors production

[Edited on 22-9-2007 by Rosco Bodine]

ROSCO you are a scream!