Nitroglycerine from sulfuric acid

[Vir Novus]

As anyone knows, nitric acid is dangerous and hard to obtain. It's also necessary for making nitroglycerine. Sulfuric acid is not quite as dangerous or hard to obtain, and it is also used for making nitroglycerine. Now, I know you can make nitric acid by mixing sulfuric acid and potassium nitrate, then distilling the resulting product. But distilling nitric acid seems hard and more than a bit dangerous.

I was thinking, would it be possible to mix sulfuric acid and potassium nitrate and then use that to make nitroglycerine? The resulting mixture would contain sulfuric acid, nitric acid, and potassium bisulfate. So I guess the question would be whether potassium bisulfate would interfere with the nitration of glycerine. I wouldn't expect it to, but this isn't something you'd want to guess at either.

So does anyone know if this would work theoretically?

[asilentbob]

It can work yeah... but with all those salts in there... its harder to stir... and harder to separate the end product. Using NH4NO3 as your nitrate source will help a bit. Double beaker distillation (though slow and annoying) works for HNO3.

You really need to do more research... theres a metric-shit-ton of info out there. Google stuff like nitroglycerin synthesis. Pay more attention to the more scientific results.

Just remember to have ice water handy.

Too low a temp and you don't get an appreciable reaction, too high and you get a run away. So You want a happy medium and a SLOW addition. If your too low and adding too fast you will end up with alot of un-nitrated glycerin in the mix, and when it starts warming up it will all start reacting at once making it harder to control the temp.

[Vir Novus]

Thanks for the info.

I understand the basics of nitroglycerine synthesis. Sulfuric acid absorbs the water from the dehydration synthesis, as well as any in the glycerine. Nitric acid does the nitration. But nitric acid is almost impossible to get ahold of whereas sulfuric acid is fairly easy to, even in the 95%+ concentrations that would be necessary to do the synthesis with.

I did find a lot of information, but I was curious as to why no one mentioned that you could just make nitroglycerine with sulfuric acid, potassium nitrate, and glycerine if in fact you can. I'm also not sure if the potassium bisulfate would precipitate out. This would make things a lot easier, as you could just decant off the liquid part and use that for the glycerine nitration.

I was interested in this because you wouldn't need $500 worth of chemistry lab equipment to prepare the nitric acid. I used to have ammonium nitrate, but I don't think I do anymore. It was only fertilizer grade, but it was still relatively pure. Would that work much better?

[wolfy_9005]

Yeh ive seen 20L drums of 48% for refilling batteries :)

And im pretty sure nitroglycerine is more dangerous then hno3....

If your still at school/have friends at school see if they'll get you some labware. It isnt that hard to get them :)

And the bucket of ice water is a good idea, better to lose your product then something worse happen....

[asilentbob]

Unfortunately an equilibrium sets up:
H2SO4 + KNO3 <---> KHSO4 + HNO3 + HSO4- + SO4(2-) + K2SO4
I don't know the exacts, but the hydrogen sulfate forms more readily than the sulfate, and it doesn't all precipitate out to the bottom, it kinda floats around making the solution a bitch to stir.

Even using calcium nitrate to form insoluble calcium sulfate... doesn't work as expected...

Unfortunately solubility of sulfates in neutral water is not the same as their solubility in concentrated sulfuric acid. Something I have actually seen no mention of in school now up to org chem II... They talk solubilities in neutral solutions and solvents all the time... not acids...

Double beaker works, I did it before I got a retort... but now I kinda wish I didn't get the retort as now I have a full org glassware set...

Its simple... a small beaker in a big beaker, put a layer of H2SO4/nitrate on the bottom of the big beaker, put the small beaker ontop of it, put some plastic (like the corner of a zip-lock bag) over the top and secure with rubber band (kinda have to guess/experiment to see which ones can take the heat and HNO3 fumes), then put ice water in the plastic cone and put the whole thing on a hot plate and gently heat it... you will get HNO3 fumes and they will condense on the cold plastic and drip into the small beaker in the center. You just need to make sure the temp doesn't get too high, and replace the ice water every once and a while. There are other references for this and other methods around the net.

Theres a pyro on a different forum who makes all his nitric like this, but relativly big scale, letting it run pretty much all day, and re-distilling the result for 95%+.

Water just slows the nitration though... you could probably use 70% HNO3, it would just take a bit longer.

Theres also a DCM extraction route... you add H2SO4 to xNitrate, let react for a while, then cool down and add DCM... HNO3 is soluble in DCM without reacting with it appreciably at cool temperatures, while the other shit isn't. So you just mix it around and pipet off the DCM layer and let the DCM evaporate off... Basicly... Personally I don't have any DCM, and don't want to order any just yet or I would be doing this. With your resources you probably would have to order DCM from some place... as extracting it from some hardware store solvent mix would require fractional distillation glass...

I'd just suggest that you find NH4NO3 and use that, or double beaker distill.

[Vir Novus]

Hey, thanks for the info guys. The double beaker thing doesn't sound hard at all, and I'm pretty sure the plastic from shopping bags would work as that's polyethylene.

I know about the ice water thing, if I was going to attempt this at all it would be outside in the winter. I'd probably need a thermometer that doesn't dissolve in aqua regia too.

As far as sulfuric acid, I have a decent amount of it that's quite pure. What about liquid fire drain opener? I know that stuff is fairly pure sulfuric acid, but I'm not sure what the actual percentage is.

[asilentbob]

Its been a while, but I think the verdict was that Liquid Fire was too heavily buffered and only really works for NC... But I never used it... so hopefully someone else will comment on it...

Rooto is common. Its 93% and mostly clear. Works for nitrations and such as is or you can boil concentrate it up to around 98%... Which I never bothered with.

Aqua regia is HCl/HNO3.

Just a normal glass thermometer will be fine. For the nitration if you only have one with a metal probe, you can cut a tight fitting piece of plastic pipe and heat seal one end and slip it over the probe to protect it from the acids... but there is a significant lag in temperature readings due to the extra layer. I used polyethylene tubing for protecting a cheapo digital thermometer... It started glitching shortly after, could have been the fumes... could have been just crappy to begin with... Your mileage may vary.

[MH-iforgotmypassword]

Its simple... a small beaker in a big beaker, put a layer of H2SO4/nitrate on the bottom of the big beaker, put the small beaker ontop of it, put some plastic (like the corner of a zip-lock bag) over the top and secure with rubber band (kinda have to guess/experiment to see which ones can take the heat and HNO3 fumes), then put ice water in the plastic cone and put the whole thing on a hot plate and gently heat it... you will get HNO3 fumes and they will condense on the cold plastic and drip into the small beaker in the center. You just need to make sure the temp doesn't get too high, and replace the ice water every once and a while. There are other references for this and other methods around the net.


That's clever. I've heard of that being done for vodka, but it makes sense to do it for this too.

And I've heard of sulfuric acid +Xnitrate being used for NG, doesn't mean its the best solution, but usually when I do synth its a small yield just for the sake of doing it, so that doesn't bother me so much.