Sciencemadness Discussion Board

easy way to synthesis nitroglycrine

idrbur - 24-6-2015 at 08:42

I am synthesising nitroglycrine but it takes too much time to make nitric acid from potassium nitrate. So can i directly use kno3 and h2so4 to make nitroglycrine.

VladimirLem - 24-6-2015 at 09:13

hard to say...i havent seen a synthesis this way...
Im pretty sure you will get an result, but if its the TRI-nitrate of NG, i dunno...maybe only the mono- or di-nitrate with small quantities of the Tri-nitrate

Go for high concentrated if you really want to have NG

nitro-genes - 24-6-2015 at 09:56

Should work, but finely powder the KNO£ before dissolving it in the sulfuric acid and make sure all the KNO3 has dissolved completely before adding any glycerin. In my experience however, using ammonium nitrate is superior for most -ol nitrations, including erythritol, ethylene glycol, glycerol, mannitol and 1,2, propanediol giving higher yields and less chance at a runaway.

[Edited on 24-6-2015 by nitro-genes]

KesterDraconis - 24-6-2015 at 10:24

It can work, however its not a good process from my experience. Even the nitroglycerin I made from ammonium nitrate and sulfuric acid was not very good form my experiments with it. Once I used my own nitric acid however, made from sulfuric acid and potassium nitrate, not only was the synthesis easier and less messy but the results were better.

That said, I don't recommend synthesizing nitroglycerin (except for maybe one drop to hit on an anvil or something), but I especially caution against synthesizing it in large quantities (greater than a couple ml or so). Its incredibly powerful, yes, but its also very dangerous* and quite the headache as well.

*its even more dangerous if your reagents are impure. DO NOT use drain cleaner sulfuric acid for example.

[Edited on 24-6-2015 by KesterDraconis]

[Edited on 24-6-2015 by KesterDraconis]

[Edited on 24-6-2015 by KesterDraconis]

Dany - 24-6-2015 at 11:56

This procedure for making nitroglycerin (NG) was taken from US Patent US20120130115 A1 [1]. The procedure uses ammonium nitrate as the nitrate source although the authors claims that other nitrate such as KNO3, NaNO3, Ca(NO3)2, etc...can also be used (See attached paper for more detailed on the manufacturing of nitroglycerin and other related nitrate esters).

Procedure taken from [1]:

"A round-bottom fask Was charged With a magnetic stir bar and 20 mL of sulfuric acid, and then chilled in an ice bath. Ammonium nitrate (13.04 g (162.9 mmol)) was added at a rate such that the temperature of the nitrating solution did not exceed 15 C. Glycerin (2 mL ,27.15 mmol), (100% purity, purchased from Sigma-Aldrich Co.) was added at a rate such that the temperature of the reaction mixture did not exceed 15 C. Once all the glycerin Was added and the temperature of the reaction mixture began to decrease, the ice bath was removed and the reaction mixture was stirred for 3 hours at ambient conditions. The reaction mixture was added in one portion to 100 g crushed ice and stirred gently until all the ice melted. The resulting emulsion Was transferred to a separatory funnel and extracted four times with 25 mL methylene chloride. The combined organic extracts Were dried With MgSO4 and then concentrated to produce NG as a clear pale yellow liquid (5.93 g of NG, a 96% yield)."

the NG was about 96% pure confirmed by NMR spectroscopy.

References:

[1] Nicholas A. Straessler, Alexander J. Paraskos, Michael P. Kramer, METHODS OF PRODUCING NITRATE ESTERS, Patent US20120130115 A1.

Dany.



Attachment: US20120130115.pdf (946kB)
This file has been downloaded 665 times



[Edited on 25-6-2015 by Dany]

Hennig Brand - 24-6-2015 at 12:07

OP, I realized that this is your first post after I typed up the following. Use common sense and keep the quantities small. Also, all the information you want and more is already in the pre-existing threads of this sub-forum.

A ratio that works well for NG or ETN is for each one gram of glycerine or erythritol use 4g dry ammonium nitrate and 6mL concentrated sulfuric acid. I have been using 91% sulfuric acid, but a higher concentration would be better at least in the case of NG. Potassium nitrate works fine too for a NG synthesis, but with ETN the thicker nitration mixture can be problematic. It is much more efficient to use concentrated nitric and sulfuric acid (mixed acid) to synthesis NG, but I have used the nitrate salt and sulfuric acid method out of convenience a few times myself.

If using potassium nitrate instead of ammonium nitrate the weight will change. Using the molar weights and the stoichiometry which shows that for each mole of either ammonium or potassium nitrate there is one mole of nitrate.

4g NH4NO3 / 80.052g/mol * 101.1032g/mol = 5.05g KNO3 per gram of glycerine to be nitrated


Thanks for the great reference Dany. The reported yield looks extremely good.



[Edited on 24-6-2015 by Hennig Brand]

idrbur - 24-6-2015 at 20:54

Thanks for the help

Praxichys - 25-6-2015 at 07:03

Here's a tip: If the KNO3/H2SO4 mix gets too thick, try using less KNO3 and a little bit of nitric acid to make up for it.

Example: ETN synthesis is a thick mess with KNO3, but if you get 50% of your -NO3 from 70% HNO3 it stays nice and stirrable, and you greatly reduce the amount of nitric acid used. For NG, even 25% substitution would probably suffice. Make sure you are adjusting the stoicheometry correctly. It also helps to gently bake and then crush the nitrate salt to a fine powder. Add the hot nitrate directly to the sulfuric acid, but do not exceed 80C or you'll start boiling out lots of HNO3. The heat makes it dissolve quickly and with mild stirring. Once it is all a clear liquid, stick it in the freezer until it hits 15C, then begin to add the substance to be nitrated, controlling the temp with an ice bath. Keep it warm, but not hot. More than 15C but less than 35C. After everything is added, remove it from the ice bath and continue to stir at room temp for about 15 minutes.

Dany - I have never thought about using organic extraction to get NG out of a nitration mix. I usually just pour the whole thing into an equal amount of water and separate the organic layer. The NG is washed with saturated bicarbonate solution, plain water, and then with saturated CaCl2 solution. The bicarb neutralizes remaining acid, the water removes lower nitrates, and the calcium chloride dries it.

Also, 150C is far too hot for both the nitrating bath and the nitroglycerin. 150C is very close to the thermal runaway point for nitroglycerin, resulting in detonation. Decomp begins at as little as 60C. (see ref)

Kester - I think the culprit for crap performance from NG - especially if lower nitrates have been washed from it - is water. Try leaving it in an open widemouth container for a day, or shaking it with saturated K2CO3 or CaCl2. Also, I typically use Rooto drain cleaner, which is pretty clean.

Dany - 25-6-2015 at 07:36

Thanks for the correction Praxichys it is 15 C not 150 C. The extraction of the aqueous solution with an organic solvent is a rapid and efficient way to get all the NG with very little water in it. The trace of water can be easily removed by adding MgSO4 or Na2SO4 to the dichloromethane (DCM). Also, DCM evaporate very easily (bp arroud 40 C) so the NG can be obtained in high yield and less work up. if DCM is not available on can also use diethyl ether for the extraction step. Sometime the formation of an emulsion complicate the separation of NG so one be add a saturated solution of NaCl to the mixture which will break the emulsion then the aqueous phase is extracted with the organic solvent.

Dany.

KesterDraconis - 25-6-2015 at 18:10

Quote: Originally posted by Praxichys  

Kester - I think the culprit for crap performance from NG - especially if lower nitrates have been washed from it - is water. Try leaving it in an open widemouth container for a day, or shaking it with saturated K2CO3 or CaCl2. Also, I typically use Rooto drain cleaner, which is pretty clean.


Will do when I get the chance. Last batch of nitroglycerin I made with ammonium nitrate was rather meh, it worked but wasn't nearly as good as I wanted.

Also, its a headache, a really big long lasting/nearly wanted to go to hospital, type headache. I most definitely don't ever want to have heart problems. I don't care if I would eventually get used to it, I would die at the eventually part.

[Edited on 26-6-2015 by KesterDraconis]

Praxichys - 26-6-2015 at 05:46

Quote: Originally posted by KesterDraconis  
Also, its a headache, a really big long lasting/nearly wanted to go to hospital, type headache.

Nitroglycerin and other nitrate esters are strong vasodilators. You can prevent the headache by using a vasoconstrictor like caffeine or nicotine. I do not smoke but I have an electronic cigarette with unflavored 12% nicotine liquid that I use if I start to get a nitro headache. It works well. You could also try an energy drink or caffeine pill.

Also, increase the ventilation of your work area, or do it outside. Run the nitration in an erlenmeyer flask instead of a beaker to reduce the amount of NG in the air. Keep your washing solutions cold to prevent evaporation. Wear gloves and never touch NG - it is easily absorbed into the skin. Be careful when washing glassware. It is easy to accidentally get NG on your hands. If you use hot water, the steam above the sink will give you a bad headache.

Remember that a therapeutic dose of NG is 0.4mg (0.0004 grams!) , and even that amount can give people headache problems. Be careful and headaches can be avoided.

KesterDraconis - 26-6-2015 at 17:12

Quote: Originally posted by Praxichys  
Quote: Originally posted by KesterDraconis  
Also, its a headache, a really big long lasting/nearly wanted to go to hospital, type headache.

Nitroglycerin and other nitrate esters are strong vasodilators. You can prevent the headache by using a vasoconstrictor like caffeine or nicotine. I do not smoke but I have an electronic cigarette with unflavored 12% nicotine liquid that I use if I start to get a nitro headache. It works well. You could also try an energy drink or caffeine pill.

Also, increase the ventilation of your work area, or do it outside. Run the nitration in an erlenmeyer flask instead of a beaker to reduce the amount of NG in the air. Keep your washing solutions cold to prevent evaporation. Wear gloves and never touch NG - it is easily absorbed into the skin. Be careful when washing glassware. It is easy to accidentally get NG on your hands. If you use hot water, the steam above the sink will give you a bad headache.

Remember that a therapeutic dose of NG is 0.4mg (0.0004 grams!) , and even that amount can give people headache problems. Be careful and headaches can be avoided.


I didn't think about doing the nitration in an Erlenmeyer flask, but I most definitely did the nitration outside, did not use hot water to wash the glassware, and wore gloves while nitrating it. What did happen that gave me my nitro headache was touching some of it (after I had synthesized it). I had finished it and was absorbing it into a paper towel to detonate it, a glove was off of one hand at one point and after I had soaked the paper towel strip in nitroglycerin I just grabbed it and placed it somewhere else about four feet away (holding it for a few seconds at most, but definitely long enough to absorb some, I have now found out!).

Caffeine is indeed the cure. I took a caffeine pill for mine, but it did not entirely go away at first (I also didn't realize at first the source of my headache), and is still one of the worst headaches I've had in sometime (I am allergic to a couple things which give me headaches, which is also BTW what I thought had triggered this one, but this took the cake in terms of pain).