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quicksilver
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| Quote: | Originally posted by Rosco Bodine
45 grams of Hexamine Dinitrate is mixed in advance with .3 grams of Urea Nitrate ,
and is gradually added at 20-25C to the
HNO3 and ammonium pyrosulfate solution , reacted for 20 minutes past
the end of the addition and the mixture
dumped onto 750 ml of crushed ice and water .
100% of theoretical yield of RDX would be 37.53 grams
80% of theoretical would be 30 grams RDX
which is about the amount which would make me happy if the reaction proceeds
according to plan . |
This would be fantastic for only 100 ml of acid!
The whole issue of the theoretical amount of acid and that which is utilized in practice puzzels me. I am turned off by the demands of acid by many
energetic material synths in patents ( twelve to one ratio is really too much for me....as in the patent we are talking about....) but at THAT level
it makes the endevour practical.
When I read 70 grams of hex to 875 grams of acid I thought I read it incorrectly and it was really 375!
What do these guys think; that acid is free or something?
I hope you try it: I am very curious.
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Rosco Bodine
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The acid utilization efficiency for RDX
really does stink when compared to
the efficiency for PETN . For example
of you take that same 100 ml of ~97%
HNO3 and dissolve in it 1 gram of urea nitrate , and while cooling in a generous capacity ice bath , sprinkle in gradually 33 grams of
pentaerythritiol at a rate so that the temperature of the well stirred mixture is kept between 18 and 23 C
( not more , red fumes appear @ 25 C ) , for a reaction time of 1 hour and then the mixture dumped over 1000ml crushed ice
and water , the product rinsed and neutralized , dried and recrystallized from
acetone will be 73.6 grams of purified PETN will be obtained , which is 96% of
theory .
So if 30 grams of RDX would be a good yield of RDX from the 100 ml of d. 1.5 HNO3 , compared with 73.6 grams of PETN
from the same 100 ml of HNO3 , the synthesis of PETN is 2.45 times more
productive in terms of the acid utilization .
Clearly the nitration economics are more favorable for PETN than for RDX .
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quicksilver
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| Quote: | Originally posted by Rosco Bodine
The acid utilization efficiency for RDX
really does stink when compared to
the efficiency for PETN . . |
No question! I had thought the same thing; in addition to the mixed acid nitration ability when dealing with PETN. The only factor when looking at the
whole comparison is that ETN (which exists as a cheap OTC source in line with hexamine) does not keep as well (to my knowlege) thus the higher priced
penta-alcohol must be utilized. {This is of course when we are speaking of OTC source for experiments and one does not have a ready chemical company.
otherwise the priice is close to the same}.
I don't want to get totally OT but that's the case isn't it? Does ETN lack the stability of it's more complex brother??? In the
E&W thread that conclusion was reached, was it not? Or did the fellows who reached it not purify their product to any reasonable extent...?
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Rosco Bodine
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Most definitely in terms of stability RDX
is better than PETN and PETN is better than ETN . But I wouldn't give ETN a bad review on stability , no worse than nitroglycerin or
nitrocellulose , if the ETN
is indeed completely nitrated ETN , well
washed , neutralized and purified , with
some stabilizing of the correct sort . My experiments with ETN have foucsed on its use as an energetic binder , and in melts
with some other materials like PETN , and
the compositions seem unchanged after
more than a year of storage , no discoloration nor odor nor weight loss .
Maybe ETN alone has lower stability compared with its eutectic compositions .
But even the unused original sample of
pure ETN isn't showing any decomposition . So I don't know what the story is with the stability problems
others have reported , maybe the material is sensitive to variations in methods and storage conditions .
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quicksilver
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I found an old post of yours (I think)....... I stumbled on it when I was looking for some info on pyrosulfate and posts from that era...You got a
yield of 300ml of 1.5 NA from ammonium nitrate and drain opener...?
We have the same set-up for distilltion, I believe. I have a 2L 24/40. Is the quote below something you remember? I saved it from a little while ago.
And if it is, it's incredible! It makes the whole RDX process appear viable even using a non-acidic anhidryde technique! 300ml is some weight.
Well worth the time and nearly dirt cheap.
OLD QUOTE:
"650 grams of the NH4NO3 prills were placed in a 2,000 ml RB 24/40 flask ,
which was equipped with a 12 X 40 mm rare earth stirbar , and heated by an Electromantle stirring mantle . The 3 way distillation adapter was equipped
with
a top thermometer , and side discharged
into a Pope Scientific flexible teflon connecting tube to an angle adapter on the top of a 600 mm Graham condenser cooled by recirculated ice water .
The discharge of the condenser was fitted with a side tubulation straight vacuum adapter having a vent line for remote discharge of any fumes from the
closed system , and a 500 ml Erlenmeyer receiving flask was pinch clamped to
the discharge of the straight adapter .
650 ml of 92% drain cleaner SA was poured through a long stem funnel inserted through the vertical opening
in the distillation adapter , and the thermometer and 24/40 bushing adapter
was then inserted to close the apparatus . The stirrer was started in
auto-reversing mode with heating at 30%
to slowly bring up the heat and gradually dissolve the prills , and then the stirring was set to maximum in single direction mode . The heating was
very gradual to allow for any offgassing which typically precedes such distillations with a
" false boil " , which requires a temporary cessation of all heating to manage . This preliminary offgassing and crud layer formation
occurred as expected , and dissipated quickly after 10 minutes , whereafter heating was resumed at 16% to initiate the distillation and reduced back
to 10% as the mixture began to foam . The reaction goes through a sort of induction period where it simply foams with a head of foam about
12 - 18 mm thick having the appearance of effervescence like the head on a mug of ale .....not a typical boiling , and the
vapor refluxes fully within the flask , not
reaching the thermometer . Dry terrycloth
toweling was wrapped around the upper part of the flask and the distillation head to insulate it against heat loss , and in a few minutes the
thermometer began to indicate rising vapor , with the first distillate coming over at 86 C and the cooling pump was started . The distillation
proceeds very smoothly almost from its own heat of reaction with very little supplemental heating at 10 to 14 % on
the rate controller . The nitric acid comes over at a rate of 1 to 2 drops per second
and the vapor is somewhat superheated
in the reaction flask , as the reaction producing the nitric acid is occuring in a range of estimated 105 - 120 C , well above the boiling point of
the nitric acid
evolving as vapor from the reaction mixture . The distillation proceeds with
a gradual increase of the temperature of
the distilling vapor , at 100 C early in the distillation , rising to 105 C @ 150 ml in the receiver , 108 C @ 170 ml , 112 C @ 200 ml , 115 C @ 225
ml , 119 C @ 280 ml , 121 C @ 300 ml .....whereupon the
heating was ended and the distillation stopped , accumulated product ~ 87% of
theory based upon NH4NO3 .
100 ml of the HNO3 was carefully weighed using a Class A volumetric flask which was carefully dried and tared in advance , using an Ohaus 311 quad
beam scale . The density of the HNO3 was determined to be 1.5003 which is about 96.8% HNO3 . The color of the acid is about like a light ale , very
pale yellow ."
WAS THIS YOUR STUFF? - It's very nice if you think it's a repeatable concept!
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Rosco Bodine
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Yeah that was my post that got misdirected to the old server during the changeover and lost in limbo for awhile . Then it was imported and pasted back
into the thread .
I am sure I once had the process worked out to quantitative yield , but thinking back on it now it seems like it may have been a two stage
distillation which I was doing years ago . There was a routine where an excess of H2SO4 was used to first distill d. 1.5 nitric until a measured
quantity had come over , and then the receiver was changed , an additional amount of NH4NO3 was added and the distillation continued to produce
azeotropic nitric as a second yield utilizing the excess acid from the first distillation , and the combined " fractions " amounted to the
quantitative yield , with part being d. 1.5 HNO3 , and part being d. 1.41 HNO3 , 97% and 68% respectively .
I'll probably find the notes from where I worked it out the first time , after I work it out again . Keeping track of lab notes is the only way
not to be continually mystified by your own work 
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Boomer
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"...the receiver was changed , an additional amount of NH4NO3 was added "
I had come up with the same idea, since AN from 50-kilo sacks at 15$ per sack is *much* cheaper for me than 96% sulphuric at 7$ per litre! From memory
I mix 300g AN with 350ml SA, and after discarding the first few ml which are 'blood' red, distill off 140ml nitric, then add 150g more AN
for a second crop. I don't remember the second yield, nor the concentration. But it was over 53% for sure (giving better NC than my 53%
store-bought nitric). I know I could get over 140ml in the first step, but working without vacuum it gives a purer product stopping early.
Those 30g RDX from 100ml nitric are not *that* high IMO. I regularly get 23-25g with said acid and 50g HDN, which is just under 60% of theory. IIRC
Microtek claimed 70% yield, but he might have vacuum-distilled his nitric. (You listening? Please clarify!)
Has anyone here tried *identical* batches with and without adding AN, UN, ammon persulfate etc? I'd like to see the difference in figures. NOT in
a patent but in home-brew reality!
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Rosco Bodine
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| Quote: | Originally posted by Boomer
"...the receiver was changed , an additional amount of NH4NO3 was added "
I had come up with the same idea, |
( Great minds think alike )
| Quote: |
Those 30g RDX from 100ml nitric are not *that* high IMO. I regularly get 23-25g with said acid and 50g HDN, which is just under 60% of theory.
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Big difference between 60% and 80%
and getting to 90% would be a full 50% increase .
| Quote: |
Has anyone here tried *identical* batches with and without adding AN, UN, ammon persulfate etc? I'd like to see the difference in figures. NOT
in a patent but in home-brew reality! |
I have been thinking about how to most intelligently proceed with an experiment
which would seem most logical as a first
step in testing the validity of the patent
describing the use of NH4 salts in a way different from the 80 C " K- method " .
I think before going off on something of a tangent with the pyrosulfate , that first
it would be more sensible to see if the
regular sulfate will give good yields with
a lower acid ratio than the patents example 5 which produced a 91% yield ,
but using HDN instead of hexamine as in the patent , along with the lower acid
ratio .
I have neutralized some ammonium bisulfate with an excess of ammonium hydroxide in order to produce some normal ammonium sulfate for this purpose .
Even though it may add yet another variable to complicate things ,
I will probably use a small amount of urea nitrate also since there are reported benefits for doing this and I tend to do it routinely as a treatment
for d. 1.5 acid
since I don't bother clarifying it .
I have some HDN on hand so when I have time I will do a test synthesis to
see if a similar increased yield as the patents 91% can also be realized with a lower acid ratio and using HDN instead of hexamine . In my estimation
such an experiment would go directly to the heart
of the matter of real interest about improving the regular straight nitric acid
methods which use no anhydride .
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Microtek
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I got a yield of 74 % by using 1 gram HDN to 2 ml HNO3. The acid was not vacuum distilled, but was >95% and completely clear ( dry air as explained
in another thread around here ). My goal was to get the best HNO3 economy I could, as my distillation apparatus was rather small. This scheme gave
0.31 g RDX per ml HNO3.
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Rosco Bodine
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That 74% yield may hold at an even
lesser ratio of HNO3 to HDN , such as
1.7 ml HNO3 per each 1 gram HDN ,
but it is getting into the range where the
concentration of the acid is a more significant factor in whether you can
maintain yields at 74% or see diminishing yields because of the increasing dilution
of the acid from the relatively greater byproduct water from the nitrolysis .
See the attached patent page 2
Example 1 . The acid is of 99.5% concentration , and the nitrolysis
described is for hexamine . Doing
the rough mathematical analysis ,
it looks like the ratio is for each gram of hexamine ~ 3.84 ml of the HNO3 ,
producing a yield of 74.3% .
Extrapolation for HDN instead of hexamine , that is 1.7 ml of HNO3
per each 1 gram of HDN .
Perhaps the inclusion of NH4 salts which are catalytic would be of benefit that may
offset the deterioration of the acid so that
the utilization of the acid is improved sufficiently at the lower ratios to improve the economy of the reaction even with lower concentrations of HNO3
like
95 - 96 % acid . If this occurs , the economy of the nitrolysis might improve
considerably in terms of yield of RDX per
each ml of HNO3 , even with decreasing
perentage yields based on theory . For example if a significant added amount of HDN was only 50% converted to RDX ,
it would be worthwhile to gain the additional end product from the less
efficient conversion of the final portions of HDN , even though it would lower the
overall percentage yields based on theory
for HDN . The economics of the acid utilization are important enough that it
influences the rationale about where the
" extra " amount of HDN is no further value for causing diminishing return or
instability of the reaction . For example
if the basic synthesis gives 80% yields
based on HDN , and adding half again the amount of HDN reduces the theoretical yield to 65% , the overall economics favor
the 65% reaction if acid utilization is the priority . It gives me a headache to analyze these sorts of curves to find the
" sweet spot " for the economics of such reactions , a task which is only done from observing many reactions studied in depth by the devoted
bean counter
Attachment: GB658976 Cyclonite Improvements.pdf (410kB)
This file has been downloaded 1207 times
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Rosco Bodine
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The attached file may be of interest .
The last abstract is especially peculiar since most sources report decomposition
of RDX by H2SO4 .
Attachment: RDX related abstracts.pdf (81kB)
This file has been downloaded 1354 times
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quicksilver
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| Quote: |
Has anyone here tried *identical* batches with and without adding AN, UN, ammon persulfate etc? I'd like to see the difference in figures. NOT in
a patent but in home-brew reality! |
That is a whole can of worms for me. I have NOT gotten identical batches. I have used the same equip, time frame, temp. The same starting weights....I
actually can't think of an area that I can adjust at this point. Other than perhaps UV light....?
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Rosco Bodine
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The experiment which I have been contemplating , after a review of
the references believed to be pertinent ,
is as follows :
57 grams of HDN mixed dry with 0.3 grams of urea nitrate , added to 100 ml of the 96.8% HNO3 in which is dissolved
7 grams of ammonium sulfate , @ 15-20 C
with 25 minutes reaction time past the end of the addition . Based upon the
reactions believed to predominate , this should result in a spent acid concentration
of about 87% HNO3 .
Hopefully in the next few days I can perform the experiment and report some results .
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Rosco Bodine
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The experiment was done with addition of the HDN at 21 C over 30 minutes and after stirring for an additional 30 minutes the mixture was drowned . A
very poor yield of RDX resulted .
It is my belief that some heating to a higher temperature is definitely
required for these reactions which use lower amounts of HNO3 .
In early patents as well as many of the later patents which describe much higher HNO3 content mixtures , nearly all of the procedures describe heating
the mixture to some extent after all of the HDN is added and has reacted for a few minutes at a lower temperature . One patent describes heating to
40 C for a holding time of at least 1 hour , and several patents describe heating to 55 - 60 C for
at least 5 minutes , which seems to be about the minimum even for higher acid content muxtures .
Urea Nitrate is described as useful to be added to the mixture after the HDN addition and reaction at the lower temperature is completed , before the
mixture is raised to the higher temperature . At the elevated temperature there is a decompositon of byproducts , a reaction controlled and
stabilized by the urea nitrate , so that it proceeds smoothly and safely .
But I believe that it is more than just the
decomposition of byproducts which is caused by heating the mixture , particularly for the lower acid content mixtures . The heating is what actually
drives to completion the reaction which
has started at the lower temperature during which the HDN was added , so heating the mixture is essential for much more than just decomposition of
byproducts . Omitting the heating and holding time for a low acid content mixture
will therefore drastically reduce the yield ,
since the heating is necessary to drive the desired reaction to completion , regardless of the decomposition of byproducts . There is likely a
correlation between byproducts and the desired product in a low acid content mixture , so you don't get one without the other , and evidently you
get very little of either in the absence of the required heating
Actually I suspected this was true since I have experimented before with RDX many years ago and never had good yields from any experiments which did
not involve heating . But I wished to give the
" cold process " described for higher acid content mixtures in a few patents another
try to see if the added ammonium sulfate would change the reaction profile with regards to temperature , since I hate heating a mixture like this
which would seem to have so much potential for an
" event " .....wouldn't it be nice if the process could be completed at a lower temperature , reducing the fanny pucker factor by at
least 50% overall
But alas .....no such luck !
I am going to have to repeat the experiment , with the heating that appears to be essential , to get any decent yields from the low acid content
mixture . This is possibly a general rule ,
even for higher acid content mixtures , because years ago I even tried the
" cold process " with much higher acid content mixtures and had poor yields anyway even with the higher acid ratios ,
never getting any decent yields of RDX until I tried heating the mixture and discovered it was the heat which did the trick for the reaction . The
optimum temperature and holding time may be quite specific to a particular acid content reaction mixture . Just guessing , about 55 C for 5 - 10
minutes seems like a reasonable starting point for this mixture , with a subsequent experiment
at 15 - 20 minutes for comparison .
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quicksilver
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| Quote: | Originally posted by Rosco Bodine
The experiment was done with addition of the HDN at 21 C over 30 minutes and after stirring for an additional 30 minutes the mixture was drowned . A
very poor yield of RDX resulted .
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OK, in this experiment, heat was the absent from any period during the process - To the best of my understanding the heat in the older Bachmann, etc
was to reduce or eliminate liniar nirtamines. Not only reduction of unwanted nitramine formation but (fill in the possabilities)....?
What WAS the yield? Really bad....as in "20-30% bad" or worse? Do you believe that the process has no positive features, [albiet we could
use heat before that was a conclusive fact]. It SEEMED like a workable concept.
Your timing with this is fantastic as I was just going to start distilltion this morning and try it on some HDN thats dry now. I guess I'll back
off - - unless I'll try the same and & add 55C for 15 minutes and compair to the original....(?)
Hell, I think I'll run it anyway but with heat. I'll get back with my starting weights but I think I'll have enough HNO3 about 25gr.
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Rosco Bodine
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The actual yields from two experiments will not be known until the samples are completed drying . I will provide the dismal numbers when I have them
,
but from what I see it is probably on the order of a 35% yield using the ammonium sulfate cold process , and maybe 45% using a parallel warm process .
All I have confirmed by the two experiments is that
warmer is better for a low acid content mixture , both during the addition of the
HDN and for the raising of the temperature even higher afterwards .
I also am finished with ammonium sulfate which seems to be a bust , and will try ammonium nitrate as the ammonium salt for future experiments with low
acid content nitrolysis mixtures .
It appears to me that the addition of HDN is better at a rate of addition regulated 40 C than at 20 C , and that after a few minutes past the end of
the addition ,
raising to 60 C for about 10 minutes is
about right . There are visual markers for the reaction when it is actively proceeding , effervescence during the additions with a temperature rise ,
which soon subsides and has to be maintained by subsequent additions . And after the temperature is ramped up beyond 50 C ,
a second stage of effervescence occurs
with the decomposition of byproducts and/or completion of the earlier reactions . This second stage of the reaction is mildly exothermic and its
completion will be marked by a sudden dip in temperature by 4 - 5 C from the
stable temperature of 60 - 63 where it was actively effervescing . Whether it is
best to quench the mixture right then when the dip in temperature is noted ,
or whether it is best to drain the hot water bath and allow a slow cooldown before drowning the mixture , is a matter of which I am not sure .
For the warm process I mixed 1 gram of urea nitrate with the HDN , and I also mixed another 1 gram of UN with the acid
and the ammonium salt .
I did notice that the quenched reaction mixture for the warm process reeked of
formaldehyde , but the mixture from the cold process was nearly odorless .
Also I am thinking that microteks proportions are likely about the limit in terms of efficiency of acid utilization , and if that method using just
HDN and HNO3
does give 74% yield reliably , then it is
an optimized procedure which will be difficult to improve . What I am seeing
is making me doubtful of the adaptation of the patents improved yield methods for higher acid content mixtires to have similar value in improvemnet of
yields for lower acid content mixtures . But I will reserve conclusions in that matter until after tests using NH4NO3 as the ammonium salt .
I am also contemplating using even higher temperatures for finishing the reaction , 75 C perhaps , but I am unsure
if I will do this . I absolutely cringe at the prospect of heating such a mixture which seems to be heckling me and daring me .... as if it was
quietly chanting
" Sprengel rules ! "
as the mercury is steadily rising
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Microtek
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I did try a synthesis using 1 g HDN to 1.5 ml HNO3 when I was conducting this series of experiments, but got poor yields. I didn't try anything
between these concentrations.
In all the experiments I stirred the mix for 10 min at 20-30 C after end of addition, then heated to 50-55 C and held that temp for 5 min. I then
allowed it to cool down with stirring until 35 minutes had elapsed from the end of addition. Then the mix was drowned.
I used very small batches like I usually do; 4 ml HNO3 was the basis for these experiments. Therefore it may or may not be safe to scale up ( and of
course, the yield may or may not improve ).
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Boomer
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I know that industrially they use(d) efficient cooling during this stage (destruction of linear nitramines) to control the exotherm. Wonder what would
happen without cooling, and at what temp. My gut feeling tells me that with most of the hex already reacted, and the non-reacted 20-30% partly
decomposed, there would not be enough fuel for an *explosion* (ala Sprengel HE). I could imagine a runaway decomposition, but less violent than for
NG. Reason: RDX is much more thermally stable, and the mix without SA will boil off earlier, limiting the temp.
Still nothing for my kitchen... Someone else wanting to try it deliberately? 
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quicksilver
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| Quote: | Originally posted by Microtek
I used very small batches like I usually do; 4 ml HNO3 was the basis for these experiments. Therefore it may or may not be safe to scale up ( and of
course, the yield may or may not improve ). |
You got it....I am going to go over the whole of the experiment and perhaps alter temp only (perhaps just 5-10 degrees). And in addition I am going to
use the MicroTek concept. here. .
I would be really pissed if I wasted a 2-3hour distilltion. But it does seem too intriquing to not give it a try.
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Rosco Bodine
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The acid quality and concentration requirement is very rigorous in the use of low acid ratio to HDN reaction mixtures ,
and the point of diminishing returns for
using too low an acid ratio for the acid being used is a point where a sharp drop in yields will result . So it pays to err in favor of using a bit
more acid than is the minimum you estimate you need . It won't adversely affect the yield to use a little more than the minimum amount of acid ,
while it will drastically reduce the yield by a disproportionate amount if you use a little less by the same amount .
For example using 10% more acid than you estimate is needed won't impact the yield more than +1% , but using 10% too little acid can reduce the
yield by 30% .
Microtek was using a double distilled and airwashed acid . It wouldn't hurt at all
to use 10% more acid of a less refined variety acid , perhaps even 20% more , in attempting to obtain a similar yield .
Update :
The samples from my two experiments based on 55 grams HDN with 100 ml HNO3
and 7.5 grams ammonium sulfate are dried and weighed .
Cold process produced 15.5 grams
Warm process produced 19.0 grams
I believe the yield in total grams of RDX would have been greater from using only 45 grams of HDN , since it appears that 55 grams is already into the
area where there is a drastically reduced yield caused by too little excess of acid being used .
If my guess is correct , a gradual reduction of the amount of HDN will reach a point where the maximum amount of RDX is produced , and this will
represent
the point of optimization for acid utilization efficiency . The optimum amount of HDN could even be below 45 grams , perhaps 42 or even 40 grams .
[Edited on 21-11-2005 by Rosco Bodine]
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Axt
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W Process
The article I attached early in this thread is quite vague when it comes to the condensatiion of K-sulphamate with formaledhyde, doesn't give
concentrations nor pH, it must be assumed its run in acid solution as they "neutralise" it to pH5.
KOH & formaldehyde were reagent grade, sulphamic acid was dishwasher cleaner marked "99% sulphamic acid".
17.3g potassium hydroxide was dissolved into 75ml water, cooled to 0°C then added 30g sulphamic acid. pH was now 3. The solution was again cooled to
0°C a few crystals precipitated so it was about saturated. 25.1g 37% formaldehyde was added, no significant exotherm was observed and solution only
slowly raised to room temperature where it was left overnight then filtered. Yield 16.1g (35%).
17.3g potassium hydroxide was dissolved in 25ml water, into the hot solution was then added 30g sulphamic acid, some bubbling was observed. Still into
the hot solution resulting from the exothermic dissolution/neutralisation was poured 25.1g 37% formaldehyde. The solution erupted in formaldehyde
fumes and the condensation was over in about 15 seconds resulting in 22.3g (49% yield) of product.
So, I wouldn't recommend either way but it seems hot and concentrated works best. The reported yield in the article was 50%.
An attempt to nitrate the product with 30g KNO3, 100g H2SO4 & 16g condensation product resulted in nothing, After 3 hours I increased temperature
to 60°C where it went into solution but no precipitate. Solubility is a problem and it would be best to finely powder the condensation product use a
long nitration time and good stirring.
I did later find reference to it working in your HNIW thread Microtek.
"<i>By the way I got "cyclonite W" without oleum. Reaction go in KNO3-97%H2SO4 mix but yeild is lower (I get approx 45-50%: 3gRDX
from 12g K-salt 20g KNO3 30ml H2SO4). </i>" VasiaPupkin
Looks to be 50% yeild of a 50% yeild.
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Boomer
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"Cold process produced 15.5 grams
Warm process produced 19.0 grams"
That equals 34% and 41% respectively, putting it in the range of my *worst* yields from 50g/100ml without ammonia salt addition. 
This leaves the most important question open: What yield would have resulted from 55g/100ml *without* the salt addition? And secondly, what quality
was the acid? For anything but home-brew, non-vacuum nitric it 's a pity. And a proof for your over-proportional yield-reduction caused by too
much HDN.
Would you mind to try 50g and 45g with *the same* acid? And of course 55g without the ammonium sulphate, and everything at different temps please ...
we keep you busy!
When next weekend I distill my next nitric, I will do my share of tests. What I need is at least your acid density (and colour) for my results to be
of any value. I might also try the pyrosulphate, it's one of the things we have in multi-kilo bags in the company, unlike nitric
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Rosco Bodine
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The acid was good quality almost colorless , to the point that it was made colorless on the mixing with the first few crystals of urea nitrate .
I have gotten better yields from even hastily distilled red acid ...using the Hale method proportions and hexamine , so it's probably not the
acid that's the problem .
I think the yield problem resides with the proportions and temperatures and reaction times not being where they should be . It would require several
more experiments using varying proportions of
HDN to find the optimum , and then still more experiments testing the impact of NH4NO3 and I believe Urea Nitrate also , to see how the standard
reaction which has been established is affected . It may be awhile before I go further with RDX experiments , so anybody else feel free to continue
the work .
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Boomer
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I finally distilled some nitric, so here come the first results:
1. In 60ml freshly distilled nitric (d=1.53 at 0C) were dissolved 5% AN and 2.5% urea nitrate by weight. 25g HDN was added in 5 portions at 15-25C
(ice bath when needed). Mix was let stand at RT for 15 min, then heated to 55C within 3min, held there for 12.5 min and poured in 800ml ice water.
Neutralised in the filter with some 1M soda sln. then more water until neutral to litmus. Dried yield was 17.1g = 82%. HURAY
2. As above with 50ml nitric. Gave 15.4g or 74%. 
3. With 50ml but without AN + UN. Nearly dry this morning, looks like at least 15g again. (Little time and temp variations unfortunately, I'll tell
you tomorrow). ???
More coming....
[Edited on 13-12-2005 by Boomer]
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Rosco Bodine
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| Quote: | Originally posted by Boomer
I finally distilled some nitric, so here come the first results:
1. In 60ml freshly distilled nitric (d=1.53 at 0C) were dissolved 5% AN and 2.5% urea nitrate by weight. 25g HDN was added in 5 portions at 15-25C
(ice bath when needed). Mix was let stand at RT for 15 min, then heated to 55C within 3min, held there for 12.5 min and poured in 800ml ice water.
Neutralised in the filter with some 1M soda sln. then more water until neutral to litmus. Dried yield was 17.1g = 82%. HURAY
2. As above with 50ml nitric. Gave 15.4g or 74%.
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Good experiment , breaking 80% with an economic
HDN to HNO3 ratio is exactly the idea . Looks like
a good step towards a general method if it is
consistent .
Those results are tracking nicely with what I was guessing about the " sweet spot " ratio for HDN to HNO3 being something in the area of 40 to 42
grams of HDN per 100 ml of ~ 97% HNO3 . Your experiment #1 represents 41.66 grams HDN per 100 ml HNO3 . To allow a slight excess of
HNO3 and thereby provide a bit of insurance against the occasional poor yield from a reaction that is sensitive to acid quality , or other variables ,
I will probably settle for 40 grams
of HDN per 100 ml of HNO3 . To use microteks 50 grams of HDN per 100 ml HNO3 instead , would result in almost the same amount of RDX , but the
quality requirement for the acid is more stringent and it uses more HDN than Boomers proportions in example #1 . Boomers proportions would likely
give more predictable results in the presence of variables and even better predictability would be likely settling on 40 g. HDN per 100 ml HNO3 as a
rule of thumb proportion providing a bit of headroom for reactant and reaction condition variables .
The raw number yield figures for RDX should be weighed as being only part of the story concerning the efficiency of the reaction where acid
utilization is really the more significant
consideration for a lab scale synthesis , and the other factor
more important is reproducibility , getting consistent and predictable results . Increasing the excess of HNO3 favors
predictability for the reaction .
Experimenting with the effects of NH4NO3 and urea nitrate
makes sense for the likely increase in yields and the safety of the reaction . Another possibile candidate salt which may
have usefulness added to the acid is anhydrous magnesium sulfate , from baking dry epsom salt . This does react with
NH4NO3 to form a deliquescent double salt or mixture of ammonium sulfate and magnesium nitrate , which has dehydrating properties . It could possibly
function as a dehydrating agent in the nitrolysis mixture . This might benefit the yields if it did not have some other negative effect on the
reaction .
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