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ManyInterests
National Hazard
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Quote: Originally posted by DennyDevHE77  | | I don't really understand why everyone is paying attention to this. I've had fuming nitric acid on my skin many times. The result was always in the
form of yellowed skin or small ulcers later, also yellow. But it never caused any painful feelings. The most inconvenient thing was that, for example,
a nail dyed yellow would have to grow back before it returned to its color. |
I have a scar on my left hand that is a reminder of the dangers of that. I am not sure if it was something else in the acid that caused it to burn
through my skin, and this was even after I had immediately plunged my hand in a bicarbonate solution and started to pray it relentless with
bicarbonate spray (before running to the faucet and letting cool water run on my hand for a minute or so.
So I must beg your pardon, but I will need to take caution with all material.
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greenlight
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Just finished the step from nitrourea to DPT on larger scale.
This time, 40 grams of nitrourea was dissolved in 500ml of 37% formaldehyde and heated until dissolution occurred.
Sodium hydroxide solution (5%) was added to the straw yellow clear solution until pH 3 was achieved.
The solution was heated to 65°C and held for just over an hour before cooling in a water bath.
Aqueous ammonia (25%) was added dropwise with stirring until DPT crop precipitated and was vacuum filtered before repeating this base addition two
more times.
The DPT product was very light tan in colour this time which indicates some impurity that may have been formed when the temperature reached 68°C at
one point or the high acid content of the nitrourea used could have caused this.
A recrystallisation is probably the way to go before proceeding further.
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greenlight
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Final yield of DPT is 13.00 grams. It is an off-white light brown colour,.
A fresh batch of fuming nitric acid needs to be distilled and any NOx removed before the next step.
I am curious whether an increase in HMX yield can be seen from this method by the presence of phosphorus pentoxide in the nitrolysis reaction?
[Edited on 2-12-2024 by greenlight]
[Edited on 2-12-2024 by greenlight]
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greenlight
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Two nitrolysis reactions were run side by side with the DPT this time to examine whether the presence of phosphorus pentoxide could improve yields of
the final product. A fresh batch of clear colourless white fuming (~99%) nitric acid was prepared by bubbling dry air through distilled acid for 1.5
hours.
Every factor of both nitrolysis reactions was kept identical including reagent amounts, reaction times, reagent batch, temperatures, ambient
temperature and humidity, and recovery methods with the only element modified being the presence of P2O5.
Both reactions were performed in the following manner:
Refrigerated white fuming nitric acid (30.0ml) was placed into a 100ml round bottom flask with stir bar suspended in a salt-ice bath on a
hotplate/stirred and dry ammonium nitrate (10.70 g) which corresponded to approximately 10 times the molar ratio of DPT was added in small portions
and stirred in.
A digital thermometer probe (chemical proof coating) was inserted in contact with the nitrolysis mixture and when the temperature reached 5 degrees C,
DPT addition (2.5 g) was performed in small portions as to allow temperature to stay under 7 degrees C. Once addition of DPT was complete, the
mixture was stirred on ice for 30 minutes.
After 30 minutes (temperature about 3 degrees C) the flask was placed on a warm water bath on a secondary hotplate/stirrer and once 25 degrees C was
achieved (5 minutes) the temperature was held for 30 minutes between 25-26 degrees with constant stirring.
The reaction mixture was then poured into 200ml of ice water slush which resulted in instant precipitation of finely divided white solid. The
resulting solid was vacuum filtered and washed three times with ice cold distilled water before transferring to a bench to dry in air.
The only change that was made was to the second nitrolysis after ammonium nitrate addition whereupon phosphorus pentoxide (10 g) was added rapidly in
three portions into the nitrolysis mixture. Weight of P2O5 was determined by the difference in mass of the P2O5 reagent bottle before and after due
to the extreme hygroscopicity making it impossible to even weigh out and transfer to a flask.
The two reactions were run side by side in the same hood as can be seen by attached image staggered only by the initial reagent mixing and cold
reaction time (45 minutes). As soon as the first flask was moved to the warm water bath the second flask was set up and charged with reagents.
There were no issues with ammonium nitrate recrystallising out of the nitrolysis mixture during low temperature in both cases.
Both mixtures where darker yellow during time in the ice bath and lightened in colour when placed in the water bath but the mixture with phosphorus
pentoxide was darker in colour in both stages.
White smoke was noticed when adding the phosphorus pentoxide to the WFNA/NH4NO3 mixture accompanied by temperature rises each addition but no fizzing
or apparent water reaction which suggests reagents were quite anhydrous. Higher temp spikes were also noted upon DPT addition which took almost twice
as long as the first run when using just acid and ammonium nitrate.
Upon placing the two filter papers with product on them side by side (see attached image) it is readily apparent that the phosphorus pentoxide results
in a quite substantial increase in yield.
Will update on actual masses and percentages when both are fully dry.
[Edited on 17-12-2024 by greenlight]
  
[Edited on 17-12-2024 by greenlight]
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greenlight
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To ensure accurate results, the nitrolysis was repeated a second time with phosphorus pentoxide to compare with the run were it was omitted plus an
earlier run from this thread.
The dried yield results for two individual runs with and without phosphorus pentoxide were weighed and are recorded below:
* NO P2O5 RUN 1: 0.9 g HMX from 1.5 g DPT
* NO P2O5 RUN 2: 1.53 g HMX from 2.5 g DPT
* P2O5 RUN 1: 2.01 g HMX from 2.5 g DPT
* P2O5 RUN 2: 1.96 g HMX from 2.5 g DPT
The yields for nitrolysis without P2O5 are by weight 60% and 61.2% and by molar stoichiometry 37.72% and 38.48%
The yield for nitrolysis with P2O5 are by weight 80.40% and 78.40% and by molar stoichiometry 50.54% and 49.28%.
The results clearly show a substantial increase even in these small quantities when phosphorus pentoxide is present in the reaction mixture.
The phosphorus pentoxide gives a 25% increase on yield by weight and a 31% increase in yield by molar standards.
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