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[==============================================================================]
[--------------------------[ Improvised Urea Nitrate ]-------------------------]
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   ##########>.<#####    author: Mr.X
    ################       date: 2008/07/15
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1. Introduction
---------------

  In this file the properties and preparation of urea nitrate will be 
discussed. Doing some experiments, I found a convenient way to 
make it from readily available chemicals. It will be presented in this
document.

2. Chemical, physical and explosive properties of urea nitrate
--------------------------------------------------------------

       
         O
         ||
	 C
        / \
     H2N   NH2.HNO3

  Urea nitrate, as one can tell from its name, is a salt of nitric acid 
and urea. It is white crystalline substance with acidic properties. 
Solubility in cold water is low, in hot water it dissolves readily. 
Under action of concentrated sulfuric acid or other dehydrating agents 
it yields nitrourea, which is a more powerful explosive than urea nitrate. 
Urea nitrate requires a blasting cap to detonate. From my experience I can tell 
that a few grams of AP is enough. Lead block test is 260-270 cm^3, velocity of 
detonation is 3400 m/s (at density 0.85 g/cm^3)/4700 (at density 1.2 g/cm^3).
Crystal density is 1.59 g/cm^3.

3. How to make one in your basement
-----------------------------------

  Well, this is quite easy.

  Needed chemicals:
    
    1. Car battery acid (approx. 35% H2SO4, one should look for it 
       in gas stations and hardware stores).
    2. Urea (I bought it as a fertilizer).
    3. Ammonium nitrate (It's a fertilizer too, though I heard it is
       hard to get in some countries).

  Procedure:

  1. In a glass jar, add 60 grams of urea to 150 ml of water. Make sure
     urea is fully dissolved in water and there is no layer of the material
     on bottom of jar. Stir the stuff, etc.

  2. In another jar, add 107 ml battery acid, 50 ml water and 80 g of 
     ammonium nitrate. As in previous the step, make sure that the AN is fully 
     dissolved.

  3. Mix both liquids in one jar. Lots of fine urea nitrate crystals
     will appear in seconds. (Very fun to watch.)

  4. Filter the crystals off. Start to dry them. Don't discard the liquid
     that you have after filtration, it will still be useful.

  5. Put the liquid in some frosty place for a few hours. It shouldn't be
     too cold though, because that would make the solution freeze. -10 C 
     temperature was fine when I tried it. 
  
  6. Some quantity of urea nitrate crystals will be obtained from our
     liquid. Filter it off immediately after you take the mixture from your
     freezer/heap of snow and dry. We don't want UN to dissolve again.

To make UN more pure, one can recrystalize it from acetone.

Reactions that occur during this synthesis:

H2SO4 + 2NH4NO3 <--> 2HNO3 + (NH4)2SO4 (Step 2)

     O                    O
     ||                   ||
     C    + HNO3  -->     C
    / \                  / \
 H2N   NH2            H2N   NH2.HNO3

(Step 3)

4. If you can't get ammonium nitrate...
---------------------------------------

  Since I am lucky enough to live in a country that does not 
require a license to buy AN, I was making urea nitrate using it.
However, ammonium nitrate is quite unavailable to common people in 
many places. Luckily, it can be replaced by any inorganic nitrate with
good water solubility. Basically, all you need is to have 1 mol of
nitrate ions from AN. KNO3 is less soluble in water, but more 
easily available in many places than NH4NO3. To make urea nitrate 
using it, use 101 g of this substance instead of ammonium nitrate. 
In this case, the following reaction takes place during second step 
of synthesis:

H2SO4 + 2KNO3 <--> 2HNO3 + K2SO4 .

  Potassium nitrate (KNO3) is also fertilizer and one should look
for it in stores that have stuff for gardening.

  I don't think I need to rewrite the recipe. Just substitute
80 g of ammonium nitrate with 101 g of potassium nitrate and add
more water to ensure it dissolves.

5. Outro
--------

  Some recipes I have seen involve adding NH4NO3/KNO3 and urea to 
hydrochloric acid or diluted H2SO4 and mixing until you get urea 
nitrate. I found that this way isn't as convenient as preparing 
solutions in different jars and mixing them.

  Have fun.

6. References
-------------

1. T. Urbanski - Chemistry And Technology Of Explosives. Vol 3, page 469.
2. Fedoroff & Co. - Encyclopedia Of Explosives and Related Materials. 
   Vol. X, page U 102.
3. Organic Syntheses, Coll. Vol. 1, p. 417 (1941); Vol. 5, p. 85 (1925).
   http://www.orgsyn.org/orgsyn/pdfs/CV1P0417.pdf

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