EvlRenne
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DNP synthesis
Hello everyone,
I need your advice in a few questions I have regarding the following synthesis:
A 2.5-g portion of phenol and an aqueous-ethanolic solution of nitric acid, prepared from 12.5 mL of concentrated nitric acid and 50 mL of ethanol,
was mixed in a RB flask. The reaction mixture was heated in an installation with a reflux for 0.5–2 h. Then, approximately 50 mL of a liquid was
obtained by vacuum distillation. The residue was transferred to a cup. The product crystallized as yellow crystals. The crystals were washed with cold
water and dried in a vacuum-desiccator. It was found that the yield of the product depends on the reaction duration. It was 4.8, 4.8, 4.7, and 4.8 g
at reaction duration of 0.5, 1, 1.5, and 2 h, respectively, which is close to the theoretical value (4.89 g). To be purified, 2,4-dinitrophenol was
dissolved in a hot 1 M solution of NaOH and 16% activated carbon was added. In 5–10 min, the activated carbon was separated by filtration. The
filtrate was cooled and acidified with hydrochloric acid to pH 2–3. The precipitated light yellow crystals were separated from the solution by
vacuum-filtration and dried. The yield upon the purification was 80% relative to the mass of the product taken for recrystallization.
1) The first point which is alarming to me is - "dried in a vacuum-desiccator" / "vacuum-filtration and dried", taking in the account that dry DNP is
shock-sensitive and has a high chance to detonate if the moisture content drops below 15%, and "the cherry on the top of it" the amount of releasing
energy is equal to 70-75% of TNT. I am kinda worry about that, can someone comment on this?
2) Second question is related to the first one, I tried to find information regarding how to make explosives into non-explosive salt. The only salt of
DNP I found is sodium 2,4-dinitrophenolate, but this is still not the solution, as based on the pubchem the sodium salt is also the explosive.
I was trying to find any write-ups regarding how to turn DNP into fumarate or anything else, but found only some attempts to "salt it out" with
ammonia, which also leads to the formation of explosive salts. I would appreciate your comment on this as well.
Thanks in advance.
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Bonee
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the explosiveness of dry dnp is a bit overstated, with low heat and on small scale the likelihood of decompisition is not likely, I heard reports that
this paper can be successfully replicated on a 10x scale in a 2L rbf, you add everything then with very very careful and slow heating the reaction
starts at around 40-50c, then bringing to to a slow reflux and refluxing for 30min. after that either add little water and remove ethanol under
vacuum, then basify to 13-14, clean with norit, acididify with Hcl to precipitate yellow crystals.
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Boffis
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Firstly EvlRenne; from where did this procedure come? Phenol nitrates easily to the mononitro compounds (o and p) plus a lot of tar so I can't see
further nitration yielding close to theoretical yield at all let alone in the absence of sulphuric acid. So how do you know that your product is Dnp?
Secondly, dry 2,4-dinitrophenol is much less sensitive than its salts and is less sensitive than picric acid which is not particularly sensitive
anyway. The salts, particularly of the heavy metals are more sensitive and explosive than the free dinitrophenol. The ammonium salt of picric acid is
pretty insensitive so maybe the dnphenate is too but dnp is a less strong acid than picric acid and the ammonium salt may not be so stable, it may
slowly loose ammonia. There are several compendious works on nitrophenols with regards to explosive properties have you checked out the forum library?
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EvlRenne
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Quote: Originally posted by Boffis  | Firstly EvlRenne; from where did this procedure come? Phenol nitrates easily to the mononitro compounds (o and p) plus a lot of tar so I can't see
further nitration yielding close to theoretical yield at all let alone in the absence of sulphuric acid. So how do you know that your product is Dnp?
Secondly, dry 2,4-dinitrophenol is much less sensitive than its salts and is less sensitive than picric acid which is not particularly sensitive
anyway. The salts, particularly of the heavy metals are more sensitive and explosive than the free dinitrophenol. The ammonium salt of picric acid is
pretty insensitive so maybe the dnphenate is too but dnp is a less strong acid than picric acid and the ammonium salt may not be so stable, it may
slowly loose ammonia. There are several compendious works on nitrophenols with regards to explosive properties have you checked out the forum library?
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Thanks, for the tip regarding the salts.
P.S. procedure is from the attached article.
Attachment: dnp by nitration.pdf (175kB)
This file has been downloaded 155 times
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