Author Topic: distilling nitromethane question  (Read 1746 times)

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alkadelic

  • Guest
distilling nitromethane question
« on: April 26, 2004, 12:49:00 AM »
was looking at dr.drool nitro synth and since the tfse is down. was hoping to find out how i can distill RC fuel, since i dont have a fractionating column only a jacketed condenser and hotplate stirrer(flasks). Rhodium says atmospheric pressure is not inherently dangerous as long as you arent distilling it all to dryness. But is Rhodium talking about also using a fractionating column as well? Hive bee help is always and truly appreciated..

Rhodium

  • Guest
About 1-2 drops/second
« Reply #1 on: April 26, 2004, 05:18:00 AM »
Distill slowly, and you won't need a column. Collect the fraction boiling at 101°C ±1°C.


amine

  • Guest
If you're using store bought rc fuel you won't
« Reply #2 on: April 26, 2004, 08:06:00 AM »
If you're using store bought rc fuel you won't have to worry about 'distilling to dryness' as swim has found that there is a a lot of caster oil in the mix.

alkadelic

  • Guest
I will distill slowly.
« Reply #3 on: April 26, 2004, 03:36:00 PM »
I will distill slowly. But how slow should it take before reaching the 101 c, an hour or two? thank you for your replies!

Rhodium

  • Guest
It depends
« Reply #4 on: April 26, 2004, 04:53:00 PM »
Naturally, that depends on how large volume of RC fuel you are distilling, and the nitromethane content of the mixture.

You can distill faster, but expect a somewhat lower yield and purity.


grandpa

  • Guest
I think you didn't understood the meaning of slowl
« Reply #5 on: April 26, 2004, 05:55:00 PM »
I think you didn't understood the meaning of slowly.

Rhodium said to distill at a rate of 1-2 drops/second, that's slowly. It has nothing to do with the time needed to reach that temperature.

(of course if you get another fraction coming before this one you should slow down on heating and wait for the former to finish).


tweek_ez

  • Guest
swim knows it is a dead easy distillation.
« Reply #6 on: April 26, 2004, 07:05:00 PM »
swim knows it is a dead easy distillation. set normal distillation aparatus under normal atmosphere. boil each part off incrementaly. meoh bp 68C, nitro bp 101C leave caster oil bp ?real hot. I mean there aint much there except meoh,nitro and caster. Boil over at 68 then change receiving flask. boil over nitro at 101.what remains after it stops boiling is crap. the receiving flask smells vaguely like bubblegum w/ a little caster oil smell. store over baked carbonate or mgso4 to grab any water.   ;)

alkadelic

  • Guest
Thanks alot, your comments have been very...
« Reply #7 on: April 26, 2004, 10:23:00 PM »
Thanks alot, your comments have been very helpful. Thats all i need to know about this distillation. Thanks again hive bees!

Rhodium

  • Guest
Do NOT dry with carbonates
« Reply #8 on: April 26, 2004, 11:56:00 PM »
store over baked carbonate or mgso4 to grab any water.

Do NOT dry with carbonates or other basic drying agents - they react with the nitromethane! Only use Magnesium sulfate or other neutral desiccants.


wolfx

  • Guest
Why drying
« Reply #9 on: April 27, 2004, 07:56:00 PM »
Why is it recomended to dry before distillation ?

I would say if it is a vacuum distillation, it has the obvious advantage of avoiding water into the vacuum pump, but I suspect that is not the main reason. Who knows please post.

Tdurden969

  • Guest
Wolfx where is that reccomended?
« Reply #10 on: April 27, 2004, 08:11:00 PM »
Wolfx where is that reccomended? There should be little water in the fuels you're distilling it out of.

Nitromethane does form an azeotrope with water as well though.

Also it isn't really a great idea to distill MeNO2 under vac because you will loose much into the pump oil or water as Rhodium stated somewhere.


abolt

  • Guest
MeNO2
« Reply #11 on: April 28, 2004, 12:12:00 AM »
The substance decomposes on burning producing nitrogen oxides. Reacts with alkalis. Reacts violently with strong oxidants and strong reducing agents causing fire and explosion hazard. Forms shock sensitive mixture with amines.

http://siri.org/msds/mf/cards/file/0522.html




zero_nrg

  • Guest
I've vac distilled CH3NO2 under vac many times
« Reply #12 on: April 28, 2004, 10:57:00 AM »
I've vac distilled CH3NO2 under vac many times and have not noticed any appreciable difference in the operation of my vac pump.  Can´t imagine that ther´s any appreciable amount of distillate getting into the oil that affects vapor pressure. -zero

Novice

  • Guest
Anywho, if one decides to vacuum distill, make
« Reply #13 on: April 28, 2004, 11:06:00 AM »
Anywho, if one decides to vacuum distill, make sure to cool the receiving flask with an ice/water-bath so that the nitromethane vapours are kept to a minimum.

If possible, use a water aspirator instead of a mechanical 1000$ vacuum pump.

zero_nrg

  • Guest
Assuming your distillate is not condensing too
« Reply #14 on: April 28, 2004, 11:49:00 AM »
Assuming your distillate is not condensing too far down the condenser (distilling too fast), or the vac too high, there is no need for the ice/water bath IMHO. Of course the ice bath doesn´t hurt anything but isn´t necessary if the procedures used by the wise bees are followed.  -zero

wolfx

  • Guest
Drying nitromethane
« Reply #15 on: May 15, 2004, 04:06:00 PM »
I have two different drying agents :

1) Indicative Drierite ( 97 % CaSO4 + 3 % CoCl2 )

2) Dri-Z-Air ( contains calcium chloride )

This one from hardware store, much cheaper than the drierite, that is from science shop. Less than
$ 2.00 for 13 oz.

My question is, are these OK for drying nitromethane ?

ApprenticeCook

  • Guest
On rhodium’s site under chemical information...
« Reply #16 on: May 15, 2004, 07:07:00 PM »
On rhodium’s site under chemical information there is a huge document on drying agents and suitability for certain materials.


ning

  • Guest
I think they would work
« Reply #17 on: May 26, 2004, 05:18:00 PM »
As would dried epsom salts, probably.

What you want are salts that are non-basic. Bases, even fairly weak ones, transform nitroalkanes into their salts, which as I know, can be rather explosive :-[
At least, they wouldn't distill right.

So my guess would be that CaCl2, and sulfates, being salts of strong acids, are not basic enough to deprotonate nitromethane. But beware of hydroxides and carbonates, or it might be the big boom for you!


DRIVEN

  • Guest
Nitromethane from 20% R/C fuel
« Reply #18 on: June 08, 2004, 06:20:00 PM »
1L of 20% R/C fuel was placed in a 2L RBF. Distillation was performed with a 8" vigreaux column. Heat was added such that distillate formed at 1-2 drops/second.

The following fractions were collected

Fract 1: 65.5-66 deg C: 840ml (5.5hr distillation time)
Fract 2: 66-100 deg C: 15ml (10 min distillation time)
Fract 3: 100-101.5 deg C: 45ml (30 min distilation time)


About 100ml of lubricants remained in the distillation flask.  Between the first and second fractions, the temperature dropped from 66 degC to 63 degC.  During this time distillate formation slowed to a stop.  After this, the temperature increased with distillate forming again at 66 degC. The temperature increased steadily to 100 degC (fraction 2)and held at 100-101.5 degC.  Fraction 1 (mostly methanol) condensed as a film in the 3-way adapter whereas the distillate for fraction 2 and 3 condensed as droplets (perhaps more surface tension?). Fractions 2 and 3 had a more of a fruity smell relative to that of fraction 1.  When a drop of fraction 3 was dropped into fraction 1 it demonstrated light bending during mixing.

The above procedure was repeated without the vigreaux column. The results were identical.

DENSITY MEASUREMENTS:

Density measurements were perfomed by weighing accurately 1ml volume of the solution on a analytical balance.

Fraction 2: 1.01g/ml
Fraction 3: 1.07g/ml

CALCULATIONS TO DETERMINE NITROMETHANE CONTENT

Given: Density of Fract 3 is 1.07g/ml
       Density of MeOH is 0.791g/ml
       Density of Nitro is 1.137g/ml
       Let X be the fraction of Nitro
       Let 1-X be the fraction of Methanol

1.137X + (1-X)0.791 = 1.07
1.137X + 0.791-0.791X = 1.07
0.346X = 0.279
X=0.81  and 1-X = 0.19

Therefore fraction 3 contains 81% Nitro and 19% MeOH (given water is absent from the orginal fuel). Fraction 2 contains 63% Nitro and 37% MeOH.

Just for fun, a 50ul sample of fraction 3 was mixed with 100ul of water.  Two phases formed with nitromethane being the lower phase.

These results suggest that the use of a vigreaux column does not enhance the separation of nitromethane from methanol relative to normal distillation. When distillation is performed at 1-2 drops/s, 3 fractions can be obtained which have varying degrees of nitromethane concentration with 100-101.5 degC fraction being the most rich in nitromethane. Though fraction 1 was not assayed for nitromethane it would be expected to have the lowest nitromethane concentration.