Rosco Bodine
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Sprengelstoffesaure ?
Hmmmmm.....
Here's a good one . Never heard of it before ,
but it sure looks interesting , for anyone not
too fainthearted to make it anyway .....
it looks like a good candidate for being made by
a " remotely operated apparatus " 
whatchagonnacallit hydroxynitrate 
or perhaps Emmens's acid ?
Attachment: US376145 Picric Acid plus Nitric Acid addition compound.pdf (95kB)
This file has been downloaded 894 times
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chemoleo
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What do you think it is chemically?
Apart from the difficulty in nitrating PA with fuming acid, it doesn't seem unreasonably sensitive, it needing a strong detonator, or it being mixable
with solid nitrates to form moldable masses..
Never Stop to Begin, and Never Begin to Stop...
Tolerance is good. But not with the intolerant! (Wilhelm Busch)
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Rosco Bodine
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My first thought was that perhaps it was just a
nitric acid of crystallization .....similar to urea nitrate ,
in fact it made me wonder about what might result
from gentle heating or melting urea nitrate and picric acid
together ....if the same compound might be produced ,
perhaps then forming a salt with urea on cooling .
Also it is possible to form a tetranitrated phenol and I thought this to be a possibility .
The evolution of red fumes being described , makes me think that possibly something else is occurring ,
and likely an entirely new compound is resulting ,
perhaps an addition to the ring of a nitroso
bridged to the oxygen which was the hydroxyl , but
became a singlet O due to the rearrangement to the colorless form ...under the highly acidic condition ,
enabling formation of an entirely new compound .
Also the observations are not really informative , but do point out differing solubilities and melting points from
those associated with picric acid , related to crystalline materials ....which being crystalline would usually be sufficiently pure so as not to give
very different solubilities and melting points , unless a new and different compound was indeed involved .
There's not one damn thing about this in PATR .
Hehehe ...it's a mystery . Okay Sherlocks ...what is it ?
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Nitrojet
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The substance is widely referred to as Emmens’s Acid, after its inventor Stephen Emmens.
B.P. 370, 1880, describes an explosive which is made by dissolving picric acid in fuming nitric acid (sp.gr 1.52) to saturation, and then heating. Red
fumes are evolved and upon cooling a crystalline product is obtained melting at 114-115’C. This material is less soluble than picric acid in water
and alcohol. It may be used alone as an explosive or may be mixed with nitrates or chlorates, producing a more powerful explosive than picric acid. At
one time it was used for military purposes in America under the name of Emmensite, both as a propellant and as a high explosive. A short account of
this explosive can be found in “Encyclopedia of explosives and related items, Volume 5, E87”. I found nothing about its chemical structure; But
Rosco’s idea of its chemical resemblance to Urea Nitrate is interesting. Due to its lower solubility in water, the assumption of a poly nitro phenol
(tetra, Penta), becomes less probable as for such compounds the reactivity of –OH should be more than that of Picric acid, thus culminating in more
water solubility . Also the lower melting point associated with this substance suggests that it cannot be purely a tetranitrophenol
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Rosco Bodine
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Good find
I didn't cross check by Emmens name in PATR
yet .....I had just run across the patent about ten minutes before I posted it . Emmens Acid huh ?
Well it has a name , a vanity tag on the front bumper ,
so I made a good guess .
I know that picric acid can be dissolved in an equal weight of d.1.5 HNO3 at room temperature , and will
crystallize out unaltered upon dilution ....so evidently
it is warming to some temperature ( I would assume
to nearly the b.p of HNO3 ~80C as an upper limit )
which is required to produce the Emmens Acid .
This lends some credibility to another somewhat vague patent of that era which described an unidentified compound which was a complex lead picrate
salt claimed to be a substitute for mercury fulminate , whose explosive power was increased by treating the salt
with fuming nitric acid . I have a hard copy of that patent
somewhere and I know I have posted it before either here or at E&W .....I'll have to dig it up again because
now it would seem to have acquired new significance ,
understanding that it likely describes a method of making
a complex lead picrate salt that is very likely the
Emmens Acid derivative . It seemed like a very doubtful
patent , but now it has a greatly increased interest ,
since it may represent a simply made lead picrate complex / derivative which may be the only one that
might function as a legitimate initiating explosive in
terms of a substitute for mercury fulminate .
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Nitrojet
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I came into acquaintance with this explosive, a couple of years ago, when I was busy experimenting with Picric acid and its salts. I found a very
brief description of the substance in Ullmann, but due to unavailability of WFNA, I left it that time and never returned to work on it later.
At the time I do not have the slightest idea of its chemical structure. Nitration in strong nitric acid under elevated temperatures can lead to an
entirely different product from the Picric acid family. The same phenomenon can be observed in Nitration of toluene when it is to be carried out under
vigorous conditions of nitration. Single stage nitration of toluene hence is not advised since it needs very strong acids and high temperatures which
can open the aromatic ring, causing formation of carbon dioxide and Tetranitromethane.
It is however true that Picric acid is much less vulnerable to oxidation than toluene so when being attacked by strong nitric acid, the reactions
cannot possibly proceed that far.
The late 19th century rival for Mercury fulminate which is claimed to be obtainable from treating Picric acid’s Lead salt with concentrated nitric
acid may derive its exceptional initiating power from an entirely different family of explosives to which it belongs.
I am waiting for Rosco’s copy of this exotic primer!
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Rosco Bodine
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There's not a whole lot of detail in these patents which
I remembered had mentioned using d.1.5 HNO3 for
a sort of second pass reaction , through which a lead picrate
mixed salt was claimed to be increased in power .
I was very dubious about the process as described , frankly
because it seemed to me that it only would yield a very circuitous and awkward method for purification of picric acid ,
and that the multiple salt being formed therefrom was
an unidentified non-azo clathrate variant , the triple salt
basic lead picrate - lead nitrate - lead chlorate , but being produced by a non-chemist who really didn't understand the process or the product of the
synthesis for which a patent
was being granted .
It appears possible now that instead of an ordinary picrate
multiple salt , that an Emmens Acid , or as Emmens called
it a " crystal acid " multiple salt derivative is what was being
patented .
Quite frankly I am still very dubious about the entire matter
of this " Emmens Acid " .
I should correct what I said earlier about the modification of the OH group to a single O ....as I had it reversed , and that single O is the quinoid
form , the colored form ....and the OH is intact as such in the highly acid condition which favors the phenol form . Anyway Urbanski describes and
shows the different structures which may be present dependant upon the pH , and IMO this is the mechanism at work which could lead to the formation of
some sort of addition compound with nitric acid or a part thereof .....although I have not any good idea what it is . I have even considered the
possibility
that the so called " Emmens Acid " is a complete myth and
merely describes a picric acid which is transitioned by extreme acidity to the phenolic form .....not really containing anything extra , except
perhaps some adsorbed HNO3 .
When experimenting with precipitation of picric acid from HCl , it has been observed that the very pale form seems to
be a possible addition product containing occluded HCl ,
which it gradually loses by evaporation on long standing in the air ....and gradually changes to the more yellow quinoid form of picric acid .
Perhaps the " crystal acid " of Emmens
is merely a parallel description of the same phenomena as
occurs with HCl , but in Emmens Acid the acid is HNO3 which
is adsorbed into the picric acid . Emmens observed that
upon fusion that acid fumes escaped the material so this
aligns nicely with my theory that is adsorbed nitric acid of
crystallization , peculiar to the phenolic form . If it is light colored , nearly white ....and probably highly corrosive in
contact with metal , these things would be added evidence .
Attachment: US1398098 Lead Picrate Mixed Salt Primary.pdf (175kB)
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Rosco Bodine
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Here's another patent mentioning the complex lead picrate
and also describing an unusual mercury fulminate method .
Attachment: GB199489 Modified Mercury Fulminate and Lead Picrate Composition.pdf (231kB)
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Nitrojet
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A document from early 20th century describes Emmens’ Acid as:
" "Emmens" crystals are produced by treating picric acid with red fuming nitric acid (S. G., 1.52.)
The acid dissolves with the evolution of red fumes, and when cooled, (This is not very intelligible as the solution of picric acid in nitric acid
produces a lowering of the temperatures.) yields crystals stated to be different to picric acid. The liquor deposits a second crop of similar crystals
and a quantity of lustrous flakes.
These flakes, when heated in water, separate into two new bodies; one of these enters into solution and forms crystals unlike the first, while the
other body remains un-dissolved.
The acid crystals and residuum are used in conjunction with a nitrate to form an
explosive. (Spec. No.370, 10.1.88.) "Journal of Society of Chemical Industry," December 1888.
Emmens' acid would have for formula:
C13H8O.(NO2)6. 2OH,
and is therefore an intermediate between Trinitrophenol and Trinitrocresol."
Now what I do Not understand is, what it means by an intermediate between TNP and TNC?!
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Rosco Bodine
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I don't know , but it seems that Emmens was something of a legendary chemist and ordnance inventor , designed all sorts of artillery shells , fuzes ,
assorted weapons ....
evidently even patented the multifilament lightbulb like
is used on three way table lamps .....along with some
suspicion that he was actually a closet wizard and alchemist
http://www.borderlands.com/archives/arch/alchem.html
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Nitrojet
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Aside from the complexities with regard to the chemical nature of this compound, there still remains
something more to be explained and it is the very philosophy behind its invention.
Here we are treating Picric acid with the costly WFNA to get a material which is not far surpassing its precursor in explosive power or desirable
physical properties. what we are getting by consuming large amound of pure nitric acid is a slight drop in melting point and afew percent more
explosive strrength.
From an industrial standpoint, sophisticated absorption towers need to be erected for recycling the nitrous fume generated this way. 
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Nitrojet
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In January 1888 letters patent were granted to Dr. Stephen H. Emmens, of New York, for a new organic acid discovered by him, to which the name of
Emmens Acid has been given, and the compounds formed with this acid bear the general name of Emmensite.
According to Dr. Emmens, the discovery of the so-called Emmens Acid, or EACID, was purely accidental, and resulted from a mixture of picric and nitric
acids, the latter of "exceptionally high specific gravity," which had been gently warmed and set aside for some weeks, at the end of which period the
new acid had crystallized out. The existence of the new acid has been questioned, and Emmens Acid, or Eacid, has been considered by several eminent
chemists merely an isomeric form of picric acid.
According to an analysis by Dr. Wurtz, the relative percentage compositions of Eacid and picric acid are as follows:
Carbon%, 31.84% for Eacid vs. 31.44% for Picric acid
Hydrogen%, 2.04% for Eacid vs. 1.31% for Picric acid
Nitrogen%, 17.14% for Eacid vs. 18.34% for Picric acid
Oxygen% 48.98% for Eacid vs. 49.91% for Picric acid
Dr. Wurtz assigned to this acid the formula
H2C.C12H6(NO2)6O2,OH2
and regarded it as intermediate between tri-nitro-phenol and Trinitrocresol.
Professor Remsen, of the Johns Hopkins University, declared the new acid to be merely a very pure form of picric acid, while Lieut. John P. Wisser, of
the First U. S. Artillery, assistant professor of chemistry at the U. S. Military Academy, after carefully examining the new acid, stated that it was
"simply picric acid which has mechanically absorbed, probably in crystallizing, the fumes of nitric acid or the acid itself."
On the other hand, the inventor, Dr. Emmens, and Dr. Wurtz, of Pittsburgh, have maintained that the newly discovered acid is not identical with pure
picric acid. Emmens acid has been obtained in the Artillery School laboratory by dissolving picric acid at a gentle heat in fuming nitric acid (sp.
gr. 1.500 to 1.550) and evaporating the solution to about two thirds of the original volume.
Upon cooling, the new acid crystallizes out in long, transparent crystals, varying in form from prismatic to rhomboidal. In color it also differs from
picric acid, possessing a greenish-yellow rather than straw yellow color; it is also less soluble in water and alcohol, and melts at a lower
temperature, evolving brownish red fumes and undergoing change of color. All of these points of difference, however, may be explained by the theory of
Lieut. Wisser as to the composition of the new acid.
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Rosco Bodine
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"Lieut. John P. Wisser, of the First U. S. Artillery, assistant professor of chemistry at the U. S. Military Academy, after carefully examining the
new acid, stated that it was "simply picric acid which has mechanically absorbed, probably in crystallizing, the fumes of nitric acid or the acid
itself."
I would concur with that analysis with little reservation .
One test would sure settle the matter 100% .
Take a sample of the Emmens Acid and dissolve it in
boiling water to a point of saturation , then add an extra
15% to the volume of distilled H2O , followed by perhaps
5% the weight amount of the Emmens Acid having been dissolved .....with NaOH . Then add an equivalent of the
NaOH as HNO3 , HCl , or H2SO4 to the boiling solution ,
discontinue heating and allow the crystallization to
proceed with slow cooling . Test the product and see
if its properties are that of picric acid ( they will be identical ) and this should confirm Wissers finding
quite conclusively .
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Nitrojet
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Based on Wisser’s analysis, with the NaOH being added to the already saturated solution of Eacid, The occluded nitric acid together with the
absorbent Picric acid both get neutralized forming the highly soluble Alkali nitrate and the insoluble sodium Picrate.
Treating the resultant suspension with an equivalent Acid causes precipitation of Picric acid due to its limited solubility. Is it right?
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Rosco Bodine
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All I was suggesting to do is cycle the pH a bit .....
no alkali salts at all should precipitate .
But really not even that much manipulation should be necessary , as simply dissolving the Emmens Acid in boiling distilled water , till saturated at
boiling and then simply allowing to cool ,
having added nothing else but distilled water and heat ,
the product again should be only picric acid .
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Nitrojet
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Data obtained from quantitative analysis of Eacid samples does not match well with Wissers's Theory of mechanically absorbed Nitric acid. for example
carbon content must drop while Nitrogen percenatge bears a rise (compared with those of Picric acid), if we assume it to be a PA/HNO3 additional
compound, do you have any idea about it?
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Rosco Bodine
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I doubt the accuracy and significance of that analysis
and it is probably inconclusive because of margin of error
involved in such analyses of that era .
Either of the tests I suggested would be more conclusive .
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Boomer
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Some thoughts:
- With a distinct melting point different from picric, but the same after some recrystallisations, it must be something else than picric with absorbed
nitric and/or NOx.
- Picric with absorbed nitric should be more water soluble not less, at least to the same extent.
- Whatever it is, it will be fucking corrosive and hard to use, form dangerous metal salts, eat holes in detonators etc...
- If you absolutely have to make it, why not use less picric, but don't heat. The result is cheaper and more powerfull. Yep it's a sprengel explosive,
similar in power, brisance and sensitivity to NG.
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Rosco Bodine
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| Quote: | Originally posted by Boomer
Some thoughts:
- With a distinct melting point different from picric, but the same after some recrystallisations, it must be something else than picric with absorbed
nitric and/or NOx. |
Since depression of melting point is the *rule* as an indication of the presence of other substances as impurities ,
( a mixture ) , and increasing melting point to a point of no further increase after a series of recrystallizations is the *primary indicator* of a
pure substance .....it was my expectation that melting point change should follow this classical pattern .
| Quote: |
- Picric with absorbed nitric should be more water soluble not less, at least to the same extent. |
That contradicts the observation of many experiments with
recrystallizations of picric acid , where there is a distinct
reduction of solubility at lower pH which tends to also
lighten the color towards the (pH)enolic tautomer predominating It takes a
strong mineral acid like
HCl or HNO3 to effect the tautomerization of picric acid
to the lower solubility form . The effect is so predictable
that it makes picric acid useful as a narrow range color indicator , for an extremely low pH transition point of
~pH 0.2 .
| Quote: |
- Whatever it is, it will be fucking corrosive and hard to use, form dangerous metal salts, eat holes in detonators etc...
- If you absolutely have to make it, why not use less picric, but don't heat. The result is cheaper and more powerfull. Yep it's a sprengel explosive,
similar in power, brisance and sensitivity to NG. |
Evidently , heat is required for the reaction which forms the
peculiar material that was designated as Emmens Acid .
Also , evidently when it is mixed together with other materials to form the " Emmensite " composition , then
it was found to be suitable as both a high explosive for
filling artillery shells , and also as a high energy propellant
and substitute for gunpowder as a propelling charge .
The composition passed the testing requirements of that
period for military use . It would have to be relatively
low in sensitivity or it would have been rejected .
Anyway ....it is interesting , if nothing else because it is
somewhat controversial , and something that was
originated by an inventor who seemed to have a talent
for other controversial work like "transmutation" of silver
to gold
[Edited on 21-2-2007 by Rosco Bodine]
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