gveith
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Nitration of ethylene glycol in the presence of water
I know that water slows nitration of ethylene glycol. But I need to know if nitration occurs at any level when dilute nitric acid is mixed with EG.
Specifically, I have a situation where a leak of 45% EG/55% water at about 15 gallons per minute could mix with a much larger volume of 70% nitric
acid at about room temperature. I understand there will be oxidation, but I need to know if there may also be nitration that could lead to the
formation of ethylene glycol mono or dinitrates. I would greatly appreciate your responses.
Thank you.
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hissingnoise
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It's likely that the high water content in both liquids would prevent the formation of the dinitrate.
The mononitrate is explosive but it is soluble in water.
| Quote: | | Specifically, I have a situation where a leak of 45% EG/55% water at about 15 gallons per minute could mix with a much larger volume of 70% nitric
acid at about room temperature. |
You could though, be a bit more specific on this, er, unusual 'situation'. . .
[edit] The quantities involved could make for a potentially very dangerous situation, however.
[Edited on 25-5-2010 by hissingnoise]
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quicksilver
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Glycerin is hygroscopic. I believe that glycol in anhydrous form may also be - to a limited degree.
The mono or di-nitrates may always exist during synthesis of a nitric ester; the molecules do not spring into a tri-nitrated condition. As exposure to
the mixed acid continues the formation of the final synthesis develops. In other materials, they form in a much more controlled manner (TNT, TNP,
etc).
An enormous effort is placed into controlled conditions to maintain consistency with nitric esters. -- During WWII when TNT became a serious concern,
there was a period where there was a substitution of Nitro-starch for many things: engineering blasting being the most common. The effort that went
into making nitro starch consistent was a real challenge. But, in fact it was nitro starch that was the most controllable on a plant-level. Toward the
close of the War, the idea of adulterating TNT with ammonium nitrate became popular. This was more to alleviate the hassle of making a nitric ester
than as a productive way to stretch supplies of TNT.
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gveith
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Hissingnoise, the situation would be abnormal and unlikely but possible. It's in the context of a process hazard analysis for a nitric acid
purification distillation system which requires cooling, and the existing cooling system uses EG/water for reasons to do with other processes. The
point is that if the heat exchanger should leak, nitric acid EG and water will mix. If there is a potential for nitration the consequences could be
grave.
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hissingnoise
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| Quote: | | If there is a potential for nitration the consequences could be grave. |
Large volumes of reactants are likely to behave somewhat differently to lab quantities and the potential for dinitration in this case cannot be ruled
out. . .
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woelen
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I would not only be concerned about formation of nitrates. A mix of 70% HNO3 and 45% glycol can give a very exothermic reaction and if such stuff is
mixed with tens of gallons per minute this could result in huge fire and production of BIG clouds of NOx.
Exothermic reactions behave quite different on large scale. This has to do with the fact that loss of heat goes through a surface, which rises
quadratically with the size, whiule production of heat rises cubically.
E.g. if you have 1 liter of heat-producing mix in a cube, then loss of heat can occur through 6 dm3. If you have 1000 liters of the same
heat-producing mix in a cube, then loss of heat can go through 6 m3. The amount of heat produced is 1000 times the amount in the 1 liter situation,
but loss of heat can only go through a 100 times as large surface. In such situations it can be that in the 1 liter case there only is some heating of
the cube of reactants, while in the 1000 liter case there is extreme heating, boiling or even explosion of the mix.
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gveith
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Thank you woelen and Hissing. I appreciate your thoughts and insights. Woelen, given that a larger volume of reactants creates potential for greater
heat accumulation relative to smaller volumes, would, as a rule, greater heat make the formation of nitrates more or less likely?
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Anders Hoveland
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I used 70% nitric acid and was unable to make cellulose nitrate-- not even nitrating it a little bit, as it burned exactly the same as before with no
brown gas given off.
I also bubbled NO2 and O2 into 60% HNO3 solution with a paper in it. Neither did the paer become nitrated, even though bubbling these gases in is
known to concentrate nitric acid past its azeotropic boiling limit. I read somewhere that 98% HNO3 will work, but not particularly well as lots of
acid are needed to do a tiny bit of nitrating, and that conc H2SO4 makes it work much better.
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quicksilver
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Quote: Originally posted by Anders Hoveland  | I used 70% nitric acid and was unable to make cellulose nitrate-- not even nitrating it a little bit, as it burned exactly the same as before with no
brown gas given off.
I also bubbled NO2 and O2 into 60% HNO3 solution with a paper in it. Neither did the paer become nitrated, even though bubbling these gases in is
known to concentrate nitric acid past its azeotropic boiling limit. I read somewhere that 98% HNO3 will work, but not particularly well as lots of
acid are needed to do a tiny bit of nitrating, and that conc H2SO4 makes it work much better. |
Not knowing what sort of cellulose you attempted to nitrate, let me make no assumptions. However 70% HNO3 & H2SO4 are the lab standards for
generations in the nitration of cellulose for demonstration purposes. Try using toilette tissue. It's guaranteed to be pure and VERY easy to nitrate
with a common mixed acid.
In fact it's a solid source of such pure cellulose whereby exposure to a mixed acid would go a long way.
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pjig
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Never thought that something that you'd wipe your ass with could be so damn valuable!
Would this be a better material than cotton balls?( far as purity goes?)
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hissingnoise
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Fire In The Hole!!!?
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woelen
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| Quote: Originally posted by quicksilver | | Quote: Originally posted by Anders Hoveland | I used 70% nitric acid and was unable to make cellulose nitrate-- not even nitrating it a little bit, as it burned exactly the same as before with no
brown gas given off.
I also bubbled NO2 and O2 into 60% HNO3 solution with a paper in it. Neither did the paer become nitrated, even though bubbling these gases in is
known to concentrate nitric acid past its azeotropic boiling limit. I read somewhere that 98% HNO3 will work, but not particularly well as lots of
acid are needed to do a tiny bit of nitrating, and that conc H2SO4 makes it work much better. |
Not knowing what sort of cellulose you attempted to nitrate, let me make no assumptions. However 70% HNO3 & H2SO4 are the lab standards for
generations in the nitration of cellulose for demonstration purposes. Try using toilette tissue. It's guaranteed to be pure and VERY easy to nitrate
with a common mixed acid.
In fact it's a solid source of such pure cellulose whereby exposure to a mixed acid would go a long way. |
Anders Hoveland is talking about something different. You talk about a mix of conc. nitric acid and conc. sulphuric acid, Anders talks about 70% acid
only. I can imagine that such an acid does not nitrate very well.
On the other hand, 70% nitric acid can give very exothermic reactions with suitable reductors. Don't expect formation of nitrate esters (certainly not
when temperature rises), but you can have exothermic reactions which are very dangerous when large volumes are mixed. I have done an experiment with
just 53% nitric acid and IPA added. When this is done, an insanely violent reaction occurs.
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quicksilver
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Apologies; the wording did confuse me. What's more the time frame of exposure was not mentioned. I would be surprised if, using a long time frame
expose to pure cellulose, you wouldn't get some bonding.
There was an American chemist (last-named "Allen") who did some experiments with azeoptopic nitric acid around the turn of the 20th century that may
have been the source for a great deal of material published in the PATR. I believe that this effort was funded by DuPont as many of the
"stream-lining" of elements in explosives processing were highly sought after in industrial production of esters during that time.
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gregxy
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I once tried to nitrate a couple ml of propylene glycol at with 70% nitric acid at room temp. After a few minutes it started to generate red fumes and
boil out of the test tube.
A mixture of hot nitric acid and glycol could detonate if there were hundreds of
gallons even without the formation of the ester.
I can't believe you would be allowed to build a plant if there was a remote possibility
of this type of thing happening. Surely the engineers would be aware of the danger,
or the insurance company or government inspectors, (at least in the USA or Europe).
I don't think you can produce any nitric esters with 70% acid. All the water that is
present shifts the equilibrium towards the acid+alcohol side. Id be interested to
know quantatively how the amount of water effects the nitration and if the equilibrium is different for different alcohols. I've also wondered how
much ester becomes hydrolyzed
when you drown the nitrating mixture and if there is an optimal way to do that.
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quicksilver
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I believe there is a question of time in exposure that also needs to be addressed. One gram cellulose exposed to 7.5gr azeotropic nitric acid at or
below 20C for 48hr+ would be interesting. I'll start that at some point and see. I believe that Benzene bonds up (to nitrobenzene) with 70% acid.
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