Sciencemadness Discussion Board

RDX

Jermann - 17-9-2013 at 04:28

Hello to all,
I wanted to ask the opinion of this synthesis. I have read a lot about "the preparatory manual of explosive second edition" but apparently does not seem to be very reliable.
I studied in the school dedicated to winemaking and I know a little bit chemistry
Why in the second part of this synthesis using a dilute acid to 70% with sodium nitrite? The temperature does not seem too high? Doing so is not dangerous and will ruin the performance?
reaction times are not too long?

Thanks in advance (sorry for my english).
Jermann


Place 220 grams of 99% nitric acid into a beaker, and then cool to 10 Celsius by means of a cold water bath. When the temperature of the 99% nitric acid reaches about 10 Celsius, slowly add 20 grams of hexamine while stirring the 99% nitric acid and maintaining its temperature at about 10 Celsius. After the addition of the hexamine, maintain the reaction mixtures temperature at 20 Celsius for 40 minutes with constant stirring. Then place 14 grams of 70% nitric acid and 2 grams of sodium nitrite into a flask and heat to 70 Celsius. When the temperature reaches 70 Celsius, slowly add the reaction mixture while maintaining the temperature of the 70% nitric acid mixture at 70 Celsius and stirring. After the addition of the reaction mixture, continue heating at 70 Celsius for about 40 minutes. After which, remove the heat source, and allow the reaction mixture to cool to room temperature. Then place the reaction mixture into an ice bath, and cool to about 5 Celsius. Finally, add the entire reaction mixture to 500 milliliters of cold water and then filter-off the precipitated RDX product, wash with 200 milliliters of water, and then vacuum dry or air-dry.

AndersHoveland - 17-9-2013 at 04:46

It is to make nitrous acid in solution. The temperature needs to be lower both to keep the nitrous acid dissolved in solution, otherwise it will escape as nitric oxide gases, and to prevent runaway reaction.

It seems that the hexamine is being nitrosated to Hexahydro-1,3,5-trinitroso-1,3,5-triazine (so-called 'R-salt'), which happens quite readily, and this is then is hydrolyzed to the nitramine.

http://www.sciencemadness.org/talk/viewthread.php?tid=17706

[Edited on 17-9-2013 by AndersHoveland]

caterpillar - 17-9-2013 at 12:46

Purpose of 70% HNO3 + some nitrite is oxidization of linear and unstable nitramines. During this process temperature will go up and toxic gases (NO2 and CH2O) will be generated. I lost the great part of my RDX - temperature went up and reaction vessel (not a special one) cracked down. But I got some crystals of RDX, not a dust. Only few grams, but I tested them with hammer. Sound was loud. They fired with hissing sound. Anders, you are not right- when you add reaction mix to 70% HNO3, there is no hexamine at all. And no R-salt too.

golfpro - 17-9-2013 at 18:48

What is the second 70%Nitric acid and sodium nitrite thing for???

Does this improve yield?

[Edited on 18-9-2013 by golfpro]

Pulverulescent - 18-9-2013 at 01:03

Quote:
What is the second 70%Nitric acid and sodium nitrite thing for???
Does this improve yield?

It's bollocks! What you'd expect from Ledgard?
The nitrolysis calls for strong HNO3 and hexamine!

caterpillar - 18-9-2013 at 01:26

Negative. You may simple put conc HNO3 with dissolved hexamine into water You'll get white dust of RDX + some impurities- linear nitramines. If you want to get larger crystals, you may use simple water. Or small amount of 70% HNO3 + KNO2 (NaNO2). Nitrites here only to initiate oxidization (oxidation? I do not know perfect word). After oxidization has been initiated, reaction mix generates enough nitric acid. So what you really need: assume you have 70 gr of HNO3 + dissolved hexamine. You need the second vessel and into this vessel you have to put simultaneously dropwise this HNO3 and 30 gr of water with small amount of nitrite. Reaction will begin (if not, heat this vessel) and temperature will go up. Finally you'll get large crystals of RDX. This procedure is described in russian book , written by Orlova. So you can do it without 70% nitric acid at all.

Pulverulescent - 18-9-2013 at 07:32

What are you on about?

Motherload - 18-9-2013 at 08:56

Can the crude RDX obtained from standard nitrolysis be purified by standard Re-crystalization ??
If yes .... What is the purpose of the second step and waste more reagents ?

caterpillar - 18-9-2013 at 12:05

As I told you, you may perform oxidization without additional nitric acid. Therefore, there will be no wasting of useful reagents. Probably, this is the best way to get rid of impurities, which make RDX unstable. After this op you'll have diluted HNO3- but you may use it for preparation of hexamine dinitrate. Preparation of RDX from hexamine dinitrate has some advantages- it requires smaller amount of conc HNO3 and does not require WFNA- small amount of NO2, presenting in HNO3 after distillation, may cause problems, if you use hexamine. I made RDX, using dinitrate.