Hexamethylenetetramine Dinitrate (HDN) Synthesis

The way I prepared HDN was the via the HCl/NH4NO3 route. The HNO3 route gives better yields, but this was just how I did it. HDN is a pretty cool compound and can be detonated as is, or it can be used to prepare RDX which is a different story. But for now the focus is on the HDN itself. The synthesis itself is pretty straightforward and doesn't take much time to do. One quick word of warning. This stuff decomposes to formaldehyde in the presence of water, but I'll tell about that later on. Ok now onto the actual information.

The materials needed are fairly easy to procure (except the hexamine for some). Besides the hexamine, all you need is HCl and NH4NO3. Yep so that's it for this method. If you go the HNO3 way, then you just need hexamine and HNO3 but that's not the route I went.
Here's a picture of the materials – hexamine (left), ammonium nitrate (middle), and HCl (left):



The actual synthesis, like I said before, is pretty easy to do. Now again this doesn't mean that you shouldn't take all necessary safety precautions. First, 10 grams of NH4NO3 was added to 28.5 ml of 31.45% HCl and this was stirred until it was all dissolved. This solution was then chilled in the freezer. At this point, 5 grams of hexamine were added to the solution and stirred until all dissolved (or the hexamine can be dissolved in about 8 ml of water and this added with stirring). Almost immediately, a precipitate could be seen to form in the solution and the solution turned cloudy. This was quickly filtered. That's really it for the actual procedure.

Now here's the tricky part. The HDN will decompose so it must be filtered quickly. HDN decomposes to formaldehyde in the presence of water, and so prolonged contact with water will cause loss of the product. What you want to do after filtering the HDN is to pour some alcohol or acetone over it to get rid of any remaining water. Then all that's left to do is dry it out and use it. One thing to note though, the yields using this method (as compared to the HNO3 method) are pretty bad, so that's just something to expect.

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