Method 3: Fractional distillation

Method 2: Separating NM from methanol in hobby fuel - freezing

Method 1: Separating NM from methanol in hobby fuel - evaporation

It will be hard to get pure nitromethane from your fuel but you should end up with a suitable mix consisting of 50-80% NM, 12% oil and the rest methanol. Methanol evaporates considerably faster than nitromethane, so I'd first just expose it to the air and see when the volume of the liquid had dropped about the right amount. At that point, I don't know exactly how well the oil, nitromethane, and remaining methanol will separate. Do not let it evaporate below 50% of the original volume or you will end up with more oil than nitromethane.

Water and nitromethane have close to the same boiling point (not that I'd boil nitromethane) and evaporation rates so I would not attempt to mix with water.

Example racing fuel contains:

30% NM (CH3-NO2)
12% Oil (X-YZ)
58% Methanol (CH3-OH)

We first need to know the properties of the components to be able to separate them:

1. All are soluble in each other

2. NM boiling point = 101°C; freezing point = -29°C
Methanol boiling point = 65°C; freezing point = -98°C
Oil boiling point >200°C; freezing point = -10 to -30°C?

With this information we can conclude that simple freeze distillation can be the way to go. Methanol will be separated and you will be left with NM and oil mix. Freezing is, theoretically, a good way to get the methanol out. I haven’t tested it out personally but it should work. Most commercial freezers go as low as -25 to -30 Celsius which is enough to freeze the NM and thus making it easy to separate the methanol. This process should be repeated so that you ensure that you get most of the NM.

According to one forum source; it doesn’t matter if the oil is left in the mix as it won’t be able to make the compound inert. So the final mix should still be effective when creating ANNM.

Nitrometane distilation from racing fuel is fairly straightforward. It works as a classic simple distillation but to get good results you should try to fraction it as much as possible (long column, packing...). You have to use a decent distillation setup with a thermometer. And no open flames! Eletric heating!

First the temperature remains stable at the boiling point of methanol (65C). You have only methanol coming. This is by far the largest fraction. You might as well stop here or you can continue if you want to gain even purer results.

Then temperature starts rising. You are now collecting a mix of methanol and Nitromethane. This is a large fraction, don't discard it, redistill.

Then temperature stays at the boiling point of nitromethane (101C). You are now collecting nitromethane.

Then you stop getting condensates and your oil begins to smoke a bit. Turn the heat off.

If you didn't fraction your distillation enough, a second distillation will give you almost pure nitromethane.

I got 150ml of rather pure nitromethane out of a gallon of 10% nitro fuel.

And for goodness sake DON'T USE A PROPANE BURNER! I did once, and underestimated the temperature. The glass vessel melted. Luckily it didn't contain anything combustible / explosive.

The Merck index says nitromethane forms explosive salts.Therefore, I believe the extraction of nitromethane with an alkali is not a good idea. These salts are known as nitronates and are extremely unstable. This problem may occur if you boil the NM mix at 80 celsius or above. Small yellow spots may form which is the forming of nitronates. As you turn the heat off, the yellow solids will re-dissolve in the initial nitromethane fraction.

In order to separate the methanol and the nitromathane you need a much better distillation rig, with a fractionating column and a thermometer. For vacuum distillation, you may want to try using a venturi pump - they only cost about 5 USD new.

You also might want to practice fractional distillation with other, less hazardous liquids before moving on to explosives.

Note: there is no good reason why you need purer than 80% NM, so don’t go overboard on the fractional distillation. The risks and efforts are not worth it.

Дата добавления: 2015-05-31