Sciencemadness Discussion Board

Nitromethane extraction

Myfanwy - 14-2-2010 at 06:30

hello guys.
i have no chloroacetic acid and sodium nitrite, so my only option to get nitromethane is the extraction from a RC-cart fuel.
This contains 65%MeOH, 20%NM and 15% synthetic oil (?!).

i took 100ml concentrated sodium chloride solution and 100ml of the fuel and put them together.
there was a thin layer on the top.
i decantate this from the soltuion and filtered.
i got 10ml (50%). with water some of the synthetic oil precipitated.

the NM as a little bit viscous ,had an fruity odor and burned with a pale grey flame producing some nitrogen dioxide.

Could that be NM?
Tomorrow i want to do this with 1L fuel. This means i would get about 200ml NM after salting out.
then i would decantate,filtrate and distill the NM away from the oil.
i tested the NM with boric acid and no green flame was observed, while burning, the no MeOH is there.

i crashed my thermometer.
Can i ditill the NM from the synthetic oil without a thermometer?
200ml seems to be pretty good.
1L fuel costs around 5€.

[Edited on 14-2-2010 by Myfanwy]

Distilling RC fuel

xwinorb - 14-2-2010 at 07:33

First time I tried it, I had good results extracting nitromethane from 50 % RC fuel. The fuel I used had only methanol, castor oil and nitromethane. I can't no longer find this RC for sale.

Technique I used, add water enough to make two layers, the least ammount of water. Twirl it, don't shake too hard or emulsion will take a long time to settle.

Separate the bottom layer and distill.

Pay close attention to the temperature. When it goes to 100 C, collect.

You might have a big fraction with MeOH and water mixed in, boiling first. The castor oil will not distill or very little will.

For some uses, it is OK if you have nitromethane mixed with MeOH.

In this case, just distill the RC fuel, then measure the density and estimate how much nitrometane you have, assuming it is mixture of methanol and nitromethane only.

Not dangerous, just avoid sparks and flames close by.

Look at the density of methanol and nitromethane, extrapolate linearly from say 0 % nitromethane ( density = methanol density ) till 100 % nitromethane ( density = nitromethane density ).

Use two identical flasks, subtract the flask weight, compare with weight of same ammount of water to calculate density.

I have tried to extract nitro from one RC fuel with 30 % only, but I found out this brand of RC fuel had something else mixed in which was not separable with the water wash, had a funny cosmetic perfume, contaminated the nitromethane and was not separable by distillation. I was not able to get good nitro this time.

If your RC is only nitro, methanol and castor oil no problem.

More recently I have extracted nitro from an RC brand with 80 % nitromethane fuel. The above technique worked well, despite some other things mixed in in the RC fuel.

I washed with water as said above and distilled pure nitro ( I needed pure nitro, not mixed with methanol ).

Three water washes.

It distilled at 100 C - 101 C, internal temperature.

Density measured at 1.1.

As I said above, if a bit of methanol is not a problem, just distill the RC fuel, don't need to wash with water. Washing with water and distilling 20 % RC probably is going to be low yielding.

Good luck.

bahamuth - 14-2-2010 at 07:45

I tried another approach, of 40% nitromethane RC fuel IIRC.

Vacuum distilled it to remove oil, silicon based in this case.

Froze it at -80 for several days to precipitate the nitromethane, worked well, filtered it and collected.

Have it in a bottle and when I need pure i just distill it and collect the right fraction, 100-103 degrees Celsius.

Myfanwy - 15-2-2010 at 08:40

I buyed myself 2,5L 25% Nitromethane fuel.
That would give theoretical 625ml NM.
I would be glas with 500ml.

i will try now 100ml NM fuel and a concentrated NaCl solution. Because of the density of the solution the NM will swim on the top. Then decantation,filtration and distillation.

For what are you going to use the nitromethane.
i will try if NM will give higher yields of Chloropicrin, instead using picric acid.

then maybe testing explosives. . .
anyway do you know, if pure NM is detonatable with an blasting cap?

User - 15-2-2010 at 09:33

You are probably going to need quite a strong booster since pure NM is quite insensitive.
NM/nitro esters are often cap sensitive.

Myfanwy - 15-2-2010 at 11:29

okey, thanks.i think i will mix it with an oxidizer (ammonium nitrate,nitric acid etc).ANNM always detonate with 0,5g Silver acetylide, i read...

so i dont have to take so much primary explosive.

grndpndr - 25-2-2010 at 20:22

Has anyone directly tried to buy NM recently? It was OTC addmitedly quite some time ago '01'? and not w/o questions.Of course I mixed my own model airplane racing fuel back then and until relatively recently
and perhaps still ,there are recipes for RC fuel online.Normally a gallon @ locall SS, $40 back then, was shared among a club, lots of fuel.I still see as small as a qt or gallon offered online w/o any restrictions That have been obvious to me.I would be quite suprised if some proof of end use isnt required now?Its ben obvius that the content of NM even in the racing fuels is quite a bit lower than previosly.Guess it was a darwn award dumping my last 1/2 gallon.:(

[Edited on 26-2-2010 by grndpndr]

Purifying Nitromethane

cynlabz - 23-6-2010 at 13:48

I was recently out and about town, to find that several local hobby shops sell fuel mixture in massive 3L containers, said to contain a mixture of methanol and nitromethane, however, here is where the difficulty arises. No concentration is given on the container, and hence, I'd like to ask:

1) Is there any titrimetric means by which to attain the concentration of my nitromethane? (Gravimetric is possible, but titrimetric is more convenient :D)

2) Alternatively, provided I have no means of knowing the concentration of nitromethane, how would I go about purifying this safely?

The trick to the second one lies in that last bit of wording. Most sources I've found recommend distillation of the nitromethane, but given my lack of inert gas, I'd rather not take the risk of an explosion occurring. Can anyone give me some insight on the matter?

- Cynlabz

Oxydro - 23-6-2010 at 14:07

Wiki says that:

[M]odel aircraft and car glow fuel, the primary ingredient is generally methanol with some nitromethane (0% to 65%, but rarely over 30% since nitromethane is expensive compared to methanol) and 10–20% lubricants (usually castor oil and/or synthetic oil).

Also, methanol / nitromethane allegedly (wiki again) form an azeotrope, boiling @ 64.6 C and containing 9% nitromethane - that is the same boiling point (.1 degree....) as the pure methanol. So, safety aside, distillation is not the greatest.

edit: typo ( boils the same as methanol, not the same as nitromethane)

[Edited on 23-6-10 by Oxydro]

not_important - 23-6-2010 at 15:06

You don't need inert gas to distill this, consider the oxygen content of CH3NO2, and that it has been used as a monopropellant without any air. If you really want inert gas, get some dry ice or a bunch of garden limestone and cheap HCl - muratic acid.

Typical RC fuel mixes will be 10-15 % NM, not a whole lot. As you mention hobby shops and not race shops, I assume that's the mix you've seen; drag races use mixes of mostly nitromethane that are injected into the carburetion system so the total composition is lower in nitro, these additives are much easier to isolate the nitromethane from.

The azeotrope with methanol boils close the methanol at 64.7 C, not nitromethane at 101.2 C. If the mixture is 10% or less nitromethane then all you'll every be able to get is the 9% azeotrope. Note that changing the pressure changes the azeotrope composition, sometimes distilling one at one pressure and then redistilling at another will allow at least a partial separation.

Nitromethane is also a bit soluble in water, about 1 part in 10. That and the high concentration of methanol means you'll not be washing out the MeOH from the NM very simply.

You could dry 'drying' the mix with CaCl2, which will complex with the MeOH, adding the chloride to the warmed solvent and then cooling. But given the high concentration of MeOH you'll need several passes to get most of it, and I'm not sure that the nitromethane doesn't form complexes with CaCl2.

Another possibility would be to freeze it out, NM feezing at -28,5 when pure. But I've NFC as to what the MeOH-MeNO2 phase diagram looks like, and so no idea as to what temperature would freeze out what composition of MeNO2 or MeNO2+MeOH.

bunch'o data on MeNO2

Attachment: 5811x1541.pdf (110kB)
This file has been downloaded 723 times

[Edited on 23-6-2010 by not_important]


MadHatter - 23-6-2010 at 15:20

If you're in the U.S., go to this link:

I've purchased nitromethane from them in the past. Or, find a speed shop or drag strip
that carries it.

I wouldn't even attempt distillation of R/C fuel mix.

Just a possible option.

peach - 23-6-2010 at 15:42

Distill it, preferably under vacuum and with a little car(e). The methanol will pour off at first, then you'll see a second stream come through; which will be your ethereal gold. What remains after that will be castor oil.

If there was ever a place to have a no smoking rule, around a distillation of this kind would be a good idea. It's not insanely flammable as a solution, but letting vapors of it escape into enclosed spaces is a bad idea. Particularly if the solution is above it's flash point (when it reaches a partial pressure in the air that will ignite if exposed to a spark). Which is 35C in this case.

You'll set that as your boiling point if you're distilling at around 80mbar. If you can go lower, you can get the BP lower (obviously). However, you'll want some ice packs in your condensers cooling loop around those temperatures, or the nitro won't liquefy very well on the way through.

As with all distillations, those under vacuum especially, ramp the heat up gently.

[Edited on 23-6-2010 by peach]

mfilip62 - 24-6-2010 at 07:13

If anything,strictly avoid using open flame and use vacuum if possible.

After all this is painstaking,inefective,dangerous and rather complex to impossible way of obtaining NM if you don't have all the right equipment
and knowledge.

Use the google to find and buy some pure NM instead,I am pretty sure it is not that hard to find!

not_important - 24-6-2010 at 07:37

Quote: Originally posted by peach  
Distill it, preferably under vacuum and with a little car(e). The methanol will pour off at first, then you'll see a second stream come through; which will be your ethereal gold. What remains after that will be castor oil.


Given the existence of a low boiling azeotrope containing 9% MeNO2, and that RC fuel appears to be 10-15% MeNO2, there would be little to no pure MeNO2 distillate, 2/3 to nearly all coming over in the azeotrope.

cynlabz - 26-6-2010 at 18:14

Thanks for all the input guys, though admittedly I should have noted that I knew about the possibility of vacuum distillation, but have yet to attain the suitable equipment to perform cette procedure (facepalm). Special thanks to not_important for the article; quite interesting. Nonetheless I'm still curious, is there really no analytical method by which to determine the content of nitroaliphatics in a solution? Well, I suppose if this isn't the case, I'll just have to find a commercial MSDS online, or try and find some pure nitromethane for purchase....

not_important - 26-6-2010 at 20:54

Well, do you need pure MeNO2 ? For some purposes the solution in MeOH might work just fine, distilling the azeotrope using a waterbath avoids any overheating of the still pot and leaves behind oils; if the mix is say 12% or a little higher in MeNO2 then switching to vacuum distillation after removal of MeOH-MeNO2 azeotrope will allow recovery of some pure MeNO2.

As for determining the content of nitro-aliphatics in a solution, these days it's likely to be done via IR spec or GC.

As already suggested, speed/drag racing suppliers are likely sources for high-concentration or pure MeNO2.

peach - 2-7-2010 at 06:22

Quote: Originally posted by not_important  

Given the existence of a low boiling azeotrope containing 9% MeNO2, and that RC fuel appears to be 10-15% MeNO2, there would be little to no pure MeNO2 distillate, 2/3 to nearly all coming over in the azeotrope.

Yep, I'd start with a higher concentration if you can. And vacuum distill it.

bahamuth - 20-1-2012 at 04:21

Found a reference to this (Purification of Nitromethane by Crystallization) article while "browsing" through "Armarego - Purification of Laboratory Chemicals 5e".

It is related to my approach mentioned previous in this thread.

HoH - 22-3-2014 at 18:58

Many years ago I distilled NM out of 30% Nitro fuel with success. The azeotrope is real. You should get a little over 200ml of pure NM per 1L of 30% nitro. I was a bit neurotic the first few distillations and by the time I felt comfortable with the procedure, I bought a gallon of pure nitro. Now I mix my own RC fuels for my RC10 GT :D

All those years ago there was debate regarding whether or not you should vacuum distill nitromethane out of the 20%-30% fuels. Most were afraid if nitromethane vapor found its way to the pump (depending on type) this could lead to a potential explosion. All my pumps boiled water at atmospheric pressure so I never bothered, but a water aspirator is probably the safest bet if you are hesitant about this distillation.