aquaregia
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Help with Mono NitroToluene
Hello Gents,
I tried nitrating Toluene to make mono nitro toluene as follow: I mixed 160 mL of 96%H2SO4 and 105 mL of fuming HNO3 and cooled the acids to about 15
Deg C. I plkaced 115 mL of Toluene into a beaker, and dropped the acid into the Toluene in over an hour, keeping the beaker in a cold bath and
monitoring the Temp so that it did not exceed 40 Deg C.
once all the acid was mixed to the toluene, the beaker was removed from the cold bath and stirred for an additionnal 15 min. What I find surprising is
that I was expecting to get a yellow-orange oil, instead, I obtained flakes which are of a buttery color and aspect!
Does anyone of you know what is this buttery flaky product?
Thx for your help.
[Edited on 14-5-2011 by aquaregia]
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aquaregia
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gents,
I heated up the "butter" by pouring boiling water on the glass on which it is "crystallised" and it melts at about 50 Deg C . Could that be P Nitrotoluene (4-MNT)? It seems that the entire product is 4-MNT is
that is the case, with very little 2 or 3-MNT.
Can someone comfirm this?
Cheers
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hissingnoise
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ISTR, the mononitration is normally carried out at ~20°C and upping the temp may favour the p-isomer which melts @ 51.5°C which is in good
agreement with what you found.
O-nitrotoluene is a liquid @ RT!
And here could possibly be a small quantity of DNT in the mix . . .
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aquaregia
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Thank you hissing noise.
I read that when the nitration is performed around 30-40 Deg C I should get 65% p-MNT and 30% o-MNT and a small quantity of o-MNT.
My problem is that, unless o-MNT is intimately mixed with p-MNT, I do not see any! all I see is p-MNT cristal mass on top of spent acid in my
decanter.
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hissingnoise
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Toluene for TNT production has higher purity than paint-grade toluene.
So getting the third nitro onto the ring might be problematic . . .
And a fritted funnel is handy for recycling the spent acids!
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aquaregia
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hissingnoise,
I used technical grade C7H8. I am still trying to determine the product I obtained. I have a feeling somehow it could be DNT. It cristalises in very
fine starshaped needles . I think the melting point is nearer 70 Deg C that 50 Deg C... It is highly soluble in acetone.
I took a 10 cc of the product and dissolved it into a new nitrating bath. There was no heat at all being generated when mixing the two. I heated it up
to in between 90 to 100 DegC, and a reaction accured, but nowhere as exothermal as "MNT" nitration. I then maintained the mixture at 90 Deg C
artificially. I wonder what this made... It should be DNT now, unless... I it
still cooling.
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quicksilver
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Without knowing the specifics of the synthesis (acid compositions, time frame, etc) a common generalization is that yellow needles are DNT/TNT
depending upon elements of the nitration. A one pot synthesis generally makes a crude product of TNT/DNT which eventually can separate out to a low
yield TNT and DNT as an "oil". Some of this is written in the COPAE (pp148-9 & so on). I have seen some needles from a one pot synth that were
nearly 2" long (I think I have a pic in one of the threads).
Hissingnoise makes a very valuable point re: paint grade materials. Very often this is "below-technical" grade and appropriate actions or decisions
should be in place to address this. Acetone is a classic example, with a percentage of petroleum distillates being left behind from it's lab use. The
other example (that is less well known) is paint-grade (vinyl) pentaerythritol. Lower nitration products had eventually made it necessary to direct a
high standard to the precursor. When these issues arise the cost becomes a serious burden; which is one reason why RDX had always had the plant-level
edge over PETN.
{A great deal of "IF"'s but....} If you had some strong acids, you have a mp of 70 and a cluster yellow (well formed) needle crystal, it appears that
you have DNT and perhaps higher. Nitrotoluene is commonly seen as a liquid (similar to nitrated benzene, etc). Once you have solids GENERALLY speaking
you have a higher nitrated product. The para or ortho positional aspect of the molecule may account for unique mp in solids, etc. If the product can
be cleaned up to a beige crystalline w/ a mp pushing higher than 70 I think there is a better confidence level as well.
[Edited on 15-5-2011 by quicksilver]
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aquaregia
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comfirmed
OK, I measured the original product melting point and it is definetly around 50 Deg C. Now, for some reason, it would appear to be p-MNT, no visble
o-MNT.
I then repeated the procedure with the batch that was nitrated again. The aspect of the re-nitrated product is similar to MNT (pale yellow crystal
mass) but the crystals looks slightly different and the melting point IS around 70 Deg C.
what's more, the product does not smell of "almonds" it is odorless, so my guess is it is DNT. I'll try to nitrate the left over MNT to DNT. Then, for
TNT, I am not sure my H2SO4 is strong enough as it is only 96% (very sirupy).
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S.C. Wack
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So where did this exact procedure come from and what does "fuming HNO3" mean exactly - details are details. I would do the usual workup procedures
such as shaking with dilute NaOH and water and steam distillation.
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quicksilver
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The "almond smell" can be a deceptive little devil, especially in "one-pot" synths due to the product going through "stages" & leaving behind
traces of lower nitrated materials, etc.
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aquaregia
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S.C Wack,
the HNO3 is distilled using KNO3 and 96%H2SO4 using a proper distillation rig. It is yellow -orange in appearance and fumes readily. The empty part of
the bottle in which it is kept also shows NO2. My guess is that it is very concentrated indeed.
As for the melting points I am refering too above, basically, I maelted the MNT and the DNT under water in a flask, then left it to cool while
monitoring T, and noted T at which each product solidified.
I found valuable info on the TNT thread, as well as good pictures of the TNT cristal structure from our friend Quicksilver. What does surprise me is
that crystal structure of my DNT is very similar to that of Quicksilver TNT, albeit smaller. It is indeed star a shaped needle mass. If anybody
possesses good closeups pictures of DNT cristals, I'm taker...
I guess the whole problem with this synth, is that every single nitration in effect produces a mix of mono, di nitrated compound, then a mix of di and
tri nitrated species... this makes analysis of each steps pretty difficult IMHO.
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quicksilver
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One issue is that many (including myself) don't have pics from the final stages ( i.e. the "brown sugar" stage). Very exacting 3 pot synths have
better pics often enough to make a single lab worthwhile for pictures alone.
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The WiZard is In
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Prep on Deville's protonitrobenzoen can be chemical
messy. For details I would recommend a book...
Urbanski, Chemistry and Technology of Explosives, vol's
1 and 4. And probable a SL of others, however, I don't
have the time/interest....
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S.C. Wack
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Quote: Originally posted by aquaregia  | | It is yellow -orange in appearance and fumes readily. The empty part of the bottle in which it is kept also shows NO2. |
Colorless HNO3 of known concentration (a known amount of preferably the usual 68-70% product) is called for here. It is easy to make nitrotoluene
containing no dinitrotoluene (or benzoic acids), you just have to do it right.
I didn't see stirring mentioned (in the reaction part). It's a good idea.
[Edited on 16-5-2011 by S.C. Wack]
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