Sciencemadness Discussion Board - PROBLEM DETONATING PICRIC ACID

PROBLEM DETONATING PICRIC ACID

Vikascoder - 5-6-2012 at 08:51

friends i have made picric acid by using powerlab's method and it works great . the problem i am facing is in its detonation . to test whether it detonates with physical shock or not i placed it in between two coins then hit it very hard with hammer it didnt detonate it even didnt puff ,nothing happened . what could be the problem with its detonation ?. i can surely say that it is picric acid but why it is not detonating ?. i read on google that it needs a very strong confinement to detonate .will anyone please tell me a easy way to detonate it.

Hexavalent - 5-6-2012 at 09:02

Is it completely dry?

VladimirLem - 5-6-2012 at 09:25

Quote:

i read on google that it needs a very strong confinement to detonate

i guess thats your problem

u need a strong Cap (#8 or stronger) to set it off...

Fossil - 5-6-2012 at 11:21

Coins are not perfectly flat. Your picric acid may not be getting the full force of your hammer blow. Try something that has no indentations, so a perfectly flat surface. BTW wear ear plugs, even if you are outside, it wont be pleasant for you if you don't have something to protect your ears.

Vikascoder - 5-6-2012 at 19:23

my picric acid is completely dry.@VladimirLem since picric acid is used as a booster in blasting cap then it should be easy to set it off. why it will require no8 blasting cap? the persons who have detonated your picric acid please tell me how to detonate it.

Bhaskar - 6-6-2012 at 01:47

Hmm..
Why don't you try metallic salts of picric acid?
I believe you will have better luck in detonating them...

Vikascoder - 6-6-2012 at 02:07

Quote: Originally posted by Bhaskar

Hmm..
Why don't you try metallic salts of picric acid?
I believe you will have better luck in detonating them...

metallic salts are generally primary explosive i have already detonated them but they are not as powerful as TNP and i need a base charge for my blasting caps.

which one is better idea to increase the sensitivity of picri acid .
1-- mixing picric acid with little nitoglycerine.
2-- mixing picric acid with HMTD.
3-- mixing picric acid with sulfur .
they all seems to be crazy ideas but what is the best way to increase sensitivity of picric acid

SM2 - 6-6-2012 at 05:59

Bhaskars right, K picrate will probably detonate upon sufficient concussion. Trinitrophenol, no way. You need a high velocity initiator for that one. Doesn't have to be big, just need the speed. While your at it, light up a small sample of K-Picrate, and tell us how it whistles!

Vikascoder , I'd be afraid to somehow increase the sensitivity of picric acid in this uncontrolled manner. Is a slow reaction occurring? Does the sensitivity increase over time? So, will it perhaps explode on its own next time you open the jar, and scrape a few crystals between the jar threads and glass? HMTD is a high enough velocity detonator to reach the activation energy of picric acid detonation. But HMTD scares me. You really have to take extra steps to make sure it is pure. You really have to make sure it is dry, but without the use of excessive heat. Nitro is a good initiator, and it may be fast enough to take picric off w/ it. Nice thing is it's not too sensitive, so you never have to worry about nitro going off by accident. But nitro is god awfully toxic, and it behaves as it's own escipient. So getting a drop or two on your hands can easily put you out of commission for up to an hour, or worse. You'll have a miserable head-ache, and feel like you went on a long isopropyl nitrite binge - yuck! Honestly, the best luck you may have is to fill an empty CO2 or nitrous mini-cylinder with nitro-glycol, and just stick a green fuse into that. I can almost guarantee this will bring picric acid to full orgasm, and it's even less sensitive than nitro. Your results ah may vary. Please consult manual, light fuse, and get away.

[Edited on 6-6-2012 by Fennel Ass Ih Tone]

[Edited on 6-6-2012 by Fennel Ass Ih Tone]

Vikascoder - 6-6-2012 at 09:26

Quote: Originally posted by Fennel Ass Ih Tone

Bhaskars right, K picrate will probably detonate upon sufficient concussion. Trinitrophenol, no way. You need a high velocity initiator for that one. Doesn't have to be big, just need the speed. While your at it, light up a small sample of K-Picrate, and tell us how it whistles!

Vikascoder , I'd be afraid to somehow increase the sensitivity of picric acid in this uncontrolled manner. Is a slow reaction occurring? Does the sensitivity increase over time? So, will it perhaps explode on its own next time you open the jar, and scrape a few crystals between the jar threads and glass? HMTD is a high enough velocity detonator to reach the activation energy of picric acid detonation. But HMTD scares me. You really have to take extra steps to make sure it is pure. You really have to make sure it is dry, but without the use of excessive heat. Nitro is a good initiator, and it may be fast enough to take picric off w/ it. Nice thing is it's not too sensitive, so you never have to worry about nitro going off by accident. But nitro is god awfully toxic, and it behaves as it's own escipient. So getting a drop or two on your hands can easily put you out of commission for up to an hour, or worse. You'll have a miserable head-ache, and feel like you went on a long isopropyl nitrite binge - yuck! Honestly, the best luck you may have is to fill an empty CO2 or nitrous mini-cylinder with nitro-glycol, and just stick a green fuse into that. I can almost guarantee this will bring picric acid to full orgasm, and it's even less sensitive than nitro. Your results ah may vary. Please consult manual, light fuse, and get away.

[Edited on 6-6-2012 by Fennel Ass Ih Tone]

[Edited on 6-6-2012 by Fennel Ass Ih Tone]

i have already posted in my previous post that i have already detonate metal picrates but they are primary explosive and i need a base charge for my blasting cap. For this purpose i made picric acid but now i am not able to detonate. Will anyone tell me the easy way for detonating it . Or making it more sensitive so that it can be easily detonated.

mabuse_ - 6-6-2012 at 09:38

I'll just quote Mr. Quicksilver on this issue:

Quote:

There is a simple and easy method to tell if you have TNP or a lower nitrated (DNP). Take a tiny weight such as a few milligrams (like a matchhead's worth) and wrap it in aluminum foil - place it on a steel anvil (wear GOGGLES) and strike it with a steel hammer. If it pops like a toy cap you're in business. if it does not react to impact stimulation, it is either DNP or has a great deal of DNP in it. Please do NOT place a heavier amount on the anvil. IF you have TNP the bang will be unpleasant.

Maybe your nitration did not work out so well.

quicksilver - 6-6-2012 at 14:39

To achieve a TRI-NITRATION (with the majority) care in temperature control must be maintained or else the final product will have a majority of DI-NITRATION, which WILL function as a medium for metal picrates yet will not have much impact sensitivity. Often a clean TNP will be very light in color. A product that is close to pure TNP will almost be a "white-yellow", the crystals will be well formed & as little as 50Mg will pop when impact tested.
Many factors may affect this issue; temperature, time in mixed acids, quality of both precursor and acid control of nitration bath (stirring in bath i.e. exposure & quality of acids). Many nitrations of phenols/poly-pheols) will have lower nitrations exist within the end result. The percentage matters a great deal and can be altered by several components.

If you alter any nitration, - alter them one at a time and keep notes so that you find the problematic agenda

[Edited on 6-6-2012 by quicksilver]

Hennig Brand - 9-6-2012 at 09:49

Picric acid is very insensitive compared to most of the other explosives we experiment with. Its sensitivity is generally considered to be only slightly more than TNT, and much less than the nitric esters. A fairly pure sample should still pop with a firm snap from a hammer on an anvil (steel on steel). Note that even small amounts of most primary explosives will be able to generate more localized heat and pressure than a hammer blow . Picric acid, especially if impure, is known to be stubborn to initiate. Also, even large quantities in shells driven by boosters have been known to show incomplete detonation and/or low order detonation (yellow vapor and/or residue was often seen when picric acid shells were detonated). Picric acid is however very storage stable and the insentivity can be a good thing from a safety perspective.

Vikascoder - 9-6-2012 at 19:40

What about tri nitro resorcinol is it also so insensitive like picric acid or it can be easily initiated . Is there any way to make picric acid more sensitive .

Hennig Brand - 10-6-2012 at 03:55

I have only ever used trinitroresorcinol to make lead styphnate, so I don't have any personal experience. However, according to Rosco trinitroresorcinol is quite a bit easier to initiate than picric acid. There are posts by Rosco on this in the "Picric acid different instructions" thread.

I don't know that much about sensitizing Picric Acid, but there has to be lots of different things that could be mixed with it that would increase overall sensitivity. I know a very common mixture seen in some of the older books was picric acid mixed with potassium nitrate, which was apparently easier to set off. I would have to look up the exact composition. Note, that most sensitizing additives will likely decrease storage stability and produce an explosive with less overall power. Picric acid is probably best used in pure form in a compound cap, with a suitably powerful initiator to set it off.

quicksilver - 10-6-2012 at 15:03

What we are discussing is similar to Fedroff's "Hot Spot" initiation. A relatively light blow from a steel punch can produce a pop from a very low weight.
-=IF=- you can work well with sulfonation, nitrated pheonals. Spyphnic Acid is actually easier to with with than many materials. (Resorsonol) IS a bit tough to get but the yield is pretty good and lead styphate has a type of "flame spit" that allows it's utility to be quite flexible for many applications. There was a great deal written and fair pictures on this but it was back in '06-'08..

IF you can't find phenols; a good source is cattle bolices (very large, nearly pure cattle aspirin, approx $7 per pound. Often experimentation is demanded to get sulfonation is extensive and notes and mandatory.

[Edited on 10-6-2012 by quicksilver]

Vikascoder - 10-6-2012 at 19:57

Quicksilver I have made picric acid But the problem comes in increasing its sensitivity . Will any one please give valuable knowledge no the topic how to increase the sensitivity of picric acid so that it can be easily initiated without providing lots of confinement.

meaniac - 10-6-2012 at 20:39

Not my field of expertise, but knowing that lead picrate is a primary explosive, perhaps a very low concentration in the PA would increase sensitivity enough to be useful but not become dangerous. Uniform concentration would be the key.
Perhaps recrystallise the PA from hot water containing some small amount of heavy metal?

Some explosives have sensitivity depending on crystal size (tiny crystals = less sensitive). Slower cooling generally gives larger crystals. That may help.

Good luck with those experiments. Lots of people have lost vital bits of themselves messing with this stuff.

Hennig Brand - 11-6-2012 at 02:51

The solubility of lead picrate is extremely low compared to picric acid. They would most likely have to be mixed after they were made. Mixing lead picrate with picric acid would definitely increase sensitivity and of course reduce safety as well. There was a document posted in the "Picric acid different instructions" thread about initiating picric acid with only lead picrate. It involved mixing lead picrate with picric acid in certain proportions and made claims that picric acid could be initiated with just lead picrate alone. The whole thing sounded very improvised and I never got around to trying it (though I meant to).

Slow cooling of a slightly less than saturated solution of picric acid will produce larger crystals. Large picric acid crystals are known to be more sensitive to initiation. Even with large crystals, initiation of picric acid still requires a fairly potent initiator, I have found.

Something to keep in mind is that the critical diameter for picric acid is much more than for most of the other suitable candidates for a base charge. When initiating a picric acid base charge in a larger diameter casing, in order to maintain the same initiator charge height as was had with the smaller diameter casing, more initiator must be used.

A little extra confinement can also make a huge difference, especially with small charge weight (like in a cap).

Bot0nist - 11-6-2012 at 14:06

I doubt your picric acid is fully nitrated. The nitration is not trivial to get right, and there is no real easy way to determine if you have the DI or TRI variety. It took me many tries and a lot of notes to get the nitration to give me good, consistent yields of TNP. The determination that it was TNP and not mostly DNP was made with an impact testing apparatus. Wrap a small bit of TNP tightly in foil, place it on a smooth steel surface, and hit it with a smooth steel hammer. If it is TNP it WILL make your ears ring. If it is mostly DNP, you will not be able to make it pop, even with a very hard hit from the hammer. Note, the steel surfaces must be smooth. Anything bumpy or purpose will not work well for impact testing.

Before you worry about sensitizing your product, you need to get the synthesis worked out. Like I said, it is really easy to get DNP and a bunch of oxidized red crap, but when you finally get it right and get TNP, it will respond to the impact testing. I promise.

Get your synthesis right and it will pop.

[Edited on 12-6-2012 by Bot0nist]

Ral123 - 11-6-2012 at 18:35

Is the sensitivity same as RDX? I can make little rdx go off without foil from a nice hammer hit. Is the not fully nitrated product storage stable?

caterpillar - 12-6-2012 at 03:47

Quote: Originally posted by Ral123

Is the sensitivity same as RDX? I can make little rdx go off without foil from a nice hammer hit. Is the not fully nitrated product storage stable?

Picric acid is less sensitive than RDX. I do not think, that making TNP more sensitive is a good idea. Make a detonator- TATP or double salt- silver carbide-nitrate. Or make some lead picrate and use it to wake TNP up, but NEVER make sensitive secondaries.

Vikascoder - 12-6-2012 at 08:50

I need to make picric acid more sensitive for my purpose . You are correct caterpillar that in detonator it should be used as it is . But for my purpose i need to make it more sensitive . So please suggest some ways to make it more sensitive

Ral123 - 12-6-2012 at 10:06

Pour with egdn (I would never waste nice material like picric like that)... Why you need it more sensitive btw? You need less critical diameter or what?

caterpillar - 12-6-2012 at 11:48

Quote: Originally posted by Vikascoder

I need to make picric acid more sensitive for my purpose . You are correct caterpillar that in detonator it should be used as it is . But for my purpose i need to make it more sensitive . So please suggest some ways to make it more sensitive

Convert TNP to kalium picrate- it explodes, been ignited in confinement and is less sensitive than lead picrate. Or add some lead picrate to picric acid. But it will be dangerous mixture.

VladimirLem - 12-6-2012 at 11:51

Quote: Originally posted by Vikascoder

hm...maybe some percents of ammonia nitrate ?

Quote:

Ral123: egdn

hm...TNP is an acid...could be a bit dangerous?!

quicksilver - 12-6-2012 at 14:52

Quote: Originally posted by Vikascoder

Quicksilver I have made picric acid But the problem comes in increasing its sensitivity . Will any one please give valuable knowledge no the topic how to increase the sensitivity of picric acid so that it can be easily initiated without providing lots of confinement.

I would simply underline what Bot0nist had said.

With ~MOST~ nitrated phenols it takes some well practiced lab-skills to get the sulfonation, time, & temp just right. The majority of "TRI-nitrated" phenols have some lower nitrated material in your yield.
The trick is to find just what it is that is getting a much lower percentage of DI-nitrated yield. Once you manage that, the level of impact sensitivity goes very high (especially with TNP).

But realistically it can be several things. Try not to make any alteration without notes or two or more alterations at a time. What helped me a great deal is working with small quantities. This allows for greater control. Frankly In MOST ALL of my experiments I work with very small amounts. It provides a serious level of safety, it gives much finer level of HNO3 purity, it is easier to maintain temp.
There ARE several things that don't do well with scaling up or down but esters and (poly)phenols are generally fair sailing.

Once you get (TNP) to "pop" with impact, the level of true TNP vs. DNP simply HAS to be substantially higher. This is a very crude way of expressing it but if you TNP is of a VERY LIGHT yellow and has well formed crystals; you should be going in the correct direction.
I have heard of attempts at TNP with WinterGreen Oil, and I personally have worked with crushed horn and (organic) Indigo. TNP is actually NOT too tough to synthesize, however one does need the correct proportions of HIGH percentage HNO3, temp and exposure (stirring).
IF you are working with a solid nitrate for your HNO3 then make sure your NaNO3 is well crushed and purified, both potassium and ammonium nitrate will mix easier that sodium nitrate but sodium nitrate requires less to achieve the same % of HNO3.

IF your product is dark that may indicate a higher hydrogen level. BOTH TNP & DNP will produce energetic heavy metal picrates however. The most productive means of mfg lead picrate is the use of lead nitrate and following the methods to mfg ~BASIC~ lead picrate. Normal lead picrate takes a bit of care and is less energetic - aside the poorly defined "exposure-method" of mixing PbO & a picric acid requires a much more definitive synthesis that that proposed in those charming military cook-books.

[Edited on 12-6-2012 by quicksilver]

caterpillar - 12-6-2012 at 23:57

Quote: Originally posted by VladimirLem

Quote: Originally posted by Vikascoder

hm...maybe some percents of ammonia nitrate ?

Quote:

Ral123: egdn

hm...TNP is an acid...could be a bit dangerous?!

No. One great NO. AN doesn't make TNP more sensitive, but you'll surely get some trace amount of nitric acid in such mixture. Self-acceleration reaction may occur- you'll get if not explosion, but violent burning. AN can be safely mixed with ammonium picrate, but this mixture is less sensitive than pure TNP.

VladimirLem - 13-6-2012 at 08:40

Quote: Originally posted by caterpillar

Quote: Originally posted by VladimirLem

Quote: Originally posted by Vikascoder

hm...maybe some percents of ammonia nitrate ?

Quote:

Ral123: egdn

hm...TNP is an acid...could be a bit dangerous?!

hm...okay^^ good 2 know

Vikascoder - 14-6-2012 at 17:59

@quick silver :
i use powerlabs method for making picric acid just i substitute phenol with A.S.A and use 98%H2SO4 and 70% HNO3. then for finalising the product i recrystallizes it from wather and hydrochloric acid (since rosco bodine told about it in the thread picric acid :different instruction )

i have one more question to ask about picric acid
as lamda told in the thread picric acid :different instruction
Finalising the production stages and purification of Picric acid.

Picric acid can be purified by:

1. - Washing the filtered crystals with a little amount of cold Water.

2. - These washed crystals are then dissolved in a solution of Sodium carbonate (Na2CO3). A Sodium picrate solution is thus formd.

3. - This Sodium picrate solution is filtered, and Hydrochloric acid is then added. Picric acid then crystalises out as yellow precipitate.

4. - This is then dissolved in the minimum amount of boiling Water, filtered, and then cooled. Picric acid will then precipitate.

5. - The crystaline Picric acid thus obtained, is dried at 30 - 40 degrees C..

does this method gives very pure picric acid ?

Swede - 17-6-2012 at 05:50

How about checking the melting point of the sample?

TNP melts sharply at 122.5 C. 2,4 DNP melts at 108 C. Place a fleck into a melting point apparatus and slowly bring on the heat. If the sample remains strongly solidified well beyond 108 and only begins to liquify at 122 C or so, the sample should be relatively pure TNP. If you have a sad little puddle at 110 C, then the product is DNP.

A mixture of the two is going to produce a protracted melt somewhere between 108 and 122. The sharpness of the melt is a reasonable sign of purity.

Obviously one wants to use a correct apparatus and extremely small crystalline samples.

quicksilver - 18-6-2012 at 06:49

IF you have access to a workable to a melting machine: I'd think that the best. If you wash and you see a substantial diminishment in weight - again you have a good % of DNP. Mix and match. What you have the ability to work with effectively - use it. But if you feel there is a real question of reliability: study the techniques till you find one that you believe will yield accuracy.
The concept is reliability on those techniques that really are consistent Repeatability will give a great deal of comfort..

Swede - 18-6-2012 at 07:03

Agreed and understood. Having a melting point apparatus is a real asset in a home lab.

A while back, in need of a MP device immediately, and being a bit cheap, I made one that in the end performed much better than I expected, although it uses (in its current incarnation) a naked flame.

A bar of aluminum is secured, maybe 25mm x 10mm x 150mm. In the end, drill a tiny hole perhaps 10mm deep, as close to one surface as possible. Into this goes a type K thermocouple, coated liberally with heat sink compound.

The bar is placed in a vise or by some other means, is held horizontally. The sample is placed on the bar surface directly above the thermocouple. A common alcohol lamp provides the heat. By placing the lamp far away from the sample, the heat transfer down the bar and into the sample is very slow, maybe 1 degree C every 4 to 5 seconds. Moving the lamp closer creates a faster heat rise. In this way, it can be adjusted easily.

The mass of the bar is what makes it work. The entire bar gets heat soaked and prevents spikes to the sample. Using a cover glass over the sample makes it more accurate, but even without a glass, using known pure salts I verified the function of this rig to within 1 degree or so, assuming the thermocouple rig is accurate.

There are other threads describing better DIY MP rigs. Common sense applies - tiny samples, and the alcohol lamp can be replaced with an electric heat gun, or even better a cartridge heater installed into the bar and attached to a variac or some other control.

quicksilver - 27-6-2012 at 09:02

Heat-gun could be excellent - IF you have a method of measurement. Some thought and creativity could yield a very workable device!

Hennig Brand - 27-6-2012 at 14:27

I like the idea of a melting point apparatus. Now that I have read the last few posts I have more of an idea about how to build one.

Mixtures of two different substances can often have melting points that are below either of the pure samples. Mixtures of TNP and DNP were routinely melted on a hot water bath and then cast. The ability to be melted on a water bath gave these explosives a huge advantage over pure Picric Acid. They were however more insensitive and less powerful than pure picric acid.

The TNP-DNP equilibrium data table, shown below in pdf, was taken from the following journal.

THE EQUILIBRIUM DIAGRAMS AND CRYSTALLIZATION VELOCITIES OF THE SYSTEMS: (a) PICRIC ACID – 2,4-DINITROPHENOL; (b) DINITROPHENOL – TRINITROTOLUENE; (c) PICRIC ACID – DINITROPHENOL – TRINITROTOLUENE
Author: A N Campbell; E J Pritchard
Canadian Journal of Research, v25b n2 (194703): 183-197

Attachment: Picric Acid - Dinitrophenol Equilibrium Data.pdf (59kB)
This file has been downloaded 709 times

The following pdf is a few lines from the "British Textbook of Explosives" from the section on Picric Acid. It briefly describes the explosive Shellite, which is a mixture of TNP and DNP and could be melted on a hot water bath. According to the above journal, Shellite was 60% TNP.

Attachment: Shellite.pdf (76kB)
This file has been downloaded 629 times

[Edited on 27-6-2012 by Hennig Brand]

Hennig Brand - 5-7-2012 at 14:23

Shellite 60/40 was used, but it seems that Shellite 70/30 was more common after WWI. There seem to be many more references for Shellite 70/30 floating around. Googling Shellite 70/30 displays many hits.

I found an interesting bit of reading on Shellite, in the following text, which explains a little bit about why the 60/40 and 70/30 compositions were chosen.

Warship
By John Jordan, Stephen Dent

Here is a snip-it from the text.

Attachment: Shellite Evolution.pdf (134kB)
This file has been downloaded 757 times

[Edited on 5-7-2012 by Hennig Brand]

al93535 - 6-7-2012 at 09:53

Can I take a yield of mostly dinitrophenol, and nitrate it further to TNP? Or is there some danger I am overlooking?

I would like to add the DNP to cold 98% sulfuric, and cautiously add 95% hno3. Then warming the mixture just as in the original synthesis for TNP, stirring and letting it sit.

Hennig Brand - 10-7-2012 at 10:42

The best use of time and other resources, I think, is to run a strong single stage nitration right through to TNP. I have never done it, but I don't think it would be a problem to start with DNP though. Actually, once those first two nitro groups are on the ring, it should be much less sensitive to oxidation/degradation.

Read the section on Picric Acid from "The Chemistry of Powder and Explosives", I think there are processes described that involve nitrating DNP to TNP. The COPAE is available for download from the forum library.

Bot0nist - 10-7-2012 at 16:59

Quote: Originally posted by Hennig Brand

I like the idea of a melting point apparatus. Now that I have read the last few posts I have more of an idea about how to build one.

Mixtures of two different substances can often have melting points that are below either of the pure samples. Mixtures of TNP and DNP were routinely melted on a hot water bath and then cast. The ability to be melted on a water bath gave these explosives a huge advantage over pure Picric Acid. They were however more insensitive and less powerful than pure picric acid.

The TNP-DNP equilibrium data table, shown below in pdf, was taken from the following journal.

THE EQUILIBRIUM DIAGRAMS AND CRYSTALLIZATION VELOCITIES OF THE SYSTEMS: (a) PICRIC ACID – 2,4-DINITROPHENOL; (b) DINITROPHENOL – TRINITROTOLUENE; (c) PICRIC ACID – DINITROPHENOL – TRINITROTOLUENE
Author: A N Campbell; E J Pritchard
Canadian Journal of Research, v25b n2 (194703): 183-197

The following pdf is a few lines from the "British Textbook of Explosives" from the section on Picric Acid. It briefly describes the explosive Shellite, which is a mixture of TNP and DNP and could be melted on a hot water bath. According to the above journal, Shellite was 60% TNP.

[Edited on 27-6-2012 by Hennig Brand]

Thank you Henning. You're really an asset to the EM section, IMO. I had overlooked that table. I have, in the past, rigged melting point apperatus connsisting of a small brine or oil bath with slow mag stirring, a thermometer in the bath, as well as a laser surface temp reader pointed at a small foil "boat," secured with thread, that held the sample. I really like the heat gun idea though.

IME, impact testing is an easy and pratical way to determine if your TNP will preform as needed in a booster or compound cap.

[Edited on 11-7-2012 by Bot0nist]

Hennig Brand - 10-7-2012 at 19:29

Thanks, I still need to learn more general chemistry, but I know a lot more than I did three years ago.

The oil bath method sounds good. I have a bunch of large nichrome wire that I salvaged from a scraped industrial sized heating/cooling system. With an aluminum bar or other suitable thermal mass, and a descent variable power supply, good temperature control should be achievable. It would also be very clean and convenient. The nichrome wire will probably need to be insulated from the thermal mass, since the thermal mass will most likely be electrically conductive as well as thermally conductive. I was thinking of drilling a hole length wise through the thermal mass and lining it with thin glass tubing. A straight length or small coil of the nichrome wire would go through the glass tubing/liner. If aluminum was used for the thermal mass it should work, since aluminum expands much more than glass when heated. There is probably a better way to set it up, and I am still thinking it over. I think some type of electrically controlled heating element would be ideal though.

There are lots of ways to design a melting point apparatus and each design will have various pros and cons.

I am definitely going to do melting point tests on some of my TNP samples in the near future. I am very curious now.

[Edited on 11-7-2012 by Hennig Brand]

Swede - 11-7-2012 at 08:23

If you do pursue a MP apparatus, my recommendation would be to use a thermocouple. Thermocouple meters are very useful beyond a MP rig... the business end of a type K thermocouple in it's uncoated state can deal with jet engine temps, 1,000 deg. C and more, and also, the thermocouples are available coated with inert materials like PTFE.

A simple meter costs maybe $20, has big digits, and can be read at a glance or from a distance, a nice feature when your hands are busy, or are doing a nitration. As far as accuracy, no, they are not going to match a good lab glass thermometer, but for 98% of what we do, it's good enough.

Anyway, get a meter and two or three thermocouples. One for high temps (inconel sheathed), one "normal" for something like a MP setup, and a third for immersion in acids and the like.

Hennig Brand - 11-7-2012 at 14:45

A thermocouple probe and meter would be the right idea. I have a couple of cheap units, that are part of multimeters, but their accuracy is questionable. I know that there are very good ones on the market though. Like you say, the cheap meters may be good enough. A dedicated device might be a better bet than one that is part of a multimeter also.

A low ohmic value power resistor could be used to heat a piece of aluminum plate. Two power resistors, one attached on either side of an aluminum plate or block, would be a better configuration though. Small, high wattage aluminum power resistors are available, which are designed to be easily attachment to a heat sink. I think they could be used to heat a small aluminum plate up to 120C or so without a problem (I am still investigating). They are in nice convenient packages and already are very well insulated. I am sure this constitutes resistor abuse, but they should last a while, especially with only occasional use.

[Edited on 12-7-2012 by Hennig Brand]

Swede - 12-7-2012 at 04:37

Hennig, you may want to consider a cartridge heater for your heat source. I looked into these things when I was doing lead dioxide plating as a compact source of a LOT of heat. These things are cheap, and come in sizes from less than a pencil, to as big as needed for anything we'd do. There are surplus units on eBay and other places.

If you need to get to 200 or 300 C, I'm afraid the resistors would cook. Just a thought.

Hennig Brand - 12-7-2012 at 07:46

I just googled cartridge heaters and they do look like they would be the proper thing. Power resistors might still be acceptable though, especially if one only needs to go to 120C or so. Power resistors are very common and cheap and can be found surplus quite easily.

The Picric Acid - DNP equilibrium data table I posted a few posts up has the freezing points of TNP-DNP mixtures, but what I meant to post was the melting point table from the same journal. The following pdf has Picric Acid-DNP melting point and freezing point tables from the journal previously referenced.

Attachment: Picric Acid - DNP Melting Points and Freezing Points.pdf (107kB)
This file has been downloaded 652 times

[Edited on 12-7-2012 by Hennig Brand]

Hennig Brand - 12-7-2012 at 10:17

Edit:
Someone following this may want to use only the first table and corresponding equation. I think the melting and freezing points should actually be very nearly the same however, between the two tables, the differences can be quite large. The authors of the journal admit that the samples of picric acid used were not 100% pure, but were very good commercial samples. This was claimed to be deliberate, in order to better represent real life commercial material.

The two data tables above only give melting and freezing point data in increments of 10% Picric Acid (more or less in some cases). I plotted the last 5 points from each table (after the eutectic point), using Excel, and was able to get second order or quadratic equations which represent the data very well. I have made a pdf of the two graphs with quadratic equations and R squared values included.

Attachment: Plotted Data and Equations for TNP-DNP Melting Points & Freezing Points.pdf (171kB)
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Ok, I have just done a first crude melting & freezing point determination on a sample of Picric Acid made from aspirin. I basically used a crude version of the type of setup described above by Swede. Here is a picture of my first crude setup.

Crude Melting point Apparatus.JPG - 161kB

A long, narrow length of aluminum plate was used. A small hole was drilled, in the side of the aluminum strip, for the thermocouple probe just below where the sample to be melted will be placed. One end is held in the large pliers shown, and the other is gently heated with a low flame on a propane torch.

Using the quadratic equations from above, and the melting and freezing point values obtained from the first crude test, Picric Acid concentrations corresponding to both the melting and freezing points were easily calculated.

The melting point equation, obtained graphically, is as follows:

y = 0.0092x^2 - 0.8425x + 68.016

Where,
y = Percent Picric Acid
x = Melting Point in degrees Celsius

The freezing point equation, obtained graphically, is as follows:

y = 0.0044x^2 + 0.1199x + 21.45

Where,
y = Percent Picric Acid
x = Freezing Point in degrees Celsius

The temperature values collected from the first crude test were as follows:

Melting Point ~ 120 C
Freezing Point ~ 117 C

Using the equations above, the following Picric Acid concentrations were calculated:

From melting point equation:
Picric Acid concentration = 99.4 %

From freezing point equation:
Picric Acid concentration = 95.7 %

An average of the two was taken giving a result of 97.6 % Picric Acid.

The difference between the melting point and freezing point experimental results is very large. It is very likely that the melting point was overshot, because very slow accurate control of the heating was difficult. It was noticed that the thermocouple probe and meter used measured lower, by more than two degrees, than a good mercury thermometer at room temperature before the first test. A better thermometer would most likely make a tremendous difference in the accuracy of the results. The other equipment as well as the experimental technique will also be refined in the near future.

As even very small proportions of Dinitrophenol in a Picric Acid sample can dramatically change the overall sensitivity, accurate measurements are very important. This is especially important when Picric Acid is used in small charge size, as in a compound cap.

[Edited on 12-7-2012 by Hennig Brand]

Hennig Brand - 12-7-2012 at 14:45

It was stated in the above 1940's journal that the Picric Acid used during testing was a very good commercial sample, but was not 100% pure. From modern literature we know that pure Picric Acid melts at 122.5C, but in the melting point table above the value given for 100% pure Picric Acid is 121.0C. If we assume that the experimental method was good, and that the data was carefully collected for the above journal, we should be able to adjust the above equation and obtain one for actual pure picric acid.

An R squared value of 0.9986, which is very close to 1, is a strong indicator that the data taken from the melting point table above is good data.

We know that the value for 100% pure Picric Acid should be 122.5C not 121.0C, so we can do a horizontal translation to better represent actual pure Picric Acid.

The original melting point equation which was obtained graphically:
(based on melting point of 121.0C for pure TNP)

y = 0.0092x^2 - 0.8425x + 68.016

Performing a horizontal translation to the right, of 1.5 Celsius, gives the following equation:
(correcting for actual melting point of 122.5C for pure TNP)

y = 0.0092(x-1.5)^2 - 0.8425(x-1.5) + 68.016

or

y = 0.0092x^2 - 0.8701x + 69.3004

I obtained a melting point of 120C in the above crude experiment, which gave a calculated value of 99.4% Picric Acid using the original equation. Recalculating using the new equation gives a value of 97.4% Picric Acid. As was said above this experimental value is most likely still high, as the melting point was probably overshot by a small amount.

The 117C freezing point from the above experiment is probably closer to the actual melting point. The aluminum strip cools quite slowly, so obtaining an accurate freezing point is probably more likely than obtaining an accurate melting point with the simple setup used. Using the new equation, 117C corresponds to 93.4% Picric Acid. If accurate, this could explain the greater than expected insensitivity of my Picric Acid.

[Edited on 13-7-2012 by Hennig Brand]

Hennig Brand - 17-7-2012 at 16:40

I apologize for the multiple posting, but I thought I should make a correction to the previous posts.

I stated above that I thought the melting and freezing points for Picric Acid -DNP mixtures should be fairly close to one another. It looks like I was wrong. Apparently it is normal for TNP-DNP mixtures to have melting points and freezing points that differ by several degrees Celsius.

Have a look at the following section on Picric Acid from the text, "Commercial Organic Analysis". The section discussing melting and freezing points starts near the bottom of page 8.

Attachment: Picric Acid excerpt from Commercial Organic Analysis.pdf (515kB)
This file has been downloaded 1283 times

[Edited on 18-7-2012 by Hennig Brand]

detonator - 31-8-2012 at 22:39

Dry and relatively pure picric acid, can be HMTD detonate.
Use 0.2g HexaMethylene Triperoxide Diamine enough to detonate 1g of picric acid.

Vikascoder - 10-9-2012 at 05:42

Could someone help me to nitrate dinitrophenol to trinitrophenol and i have only 70% nitric acid not of further more concentration. (i have other necessary chemicals readily available-)

killswitch - 15-9-2012 at 17:17

Someone mentioned color. My picric acid is a bit yellowish, but I don't know if it's too yellow or if it's approximately right.

Note: the powdered form seemed considerably lighter in color.

<a href="http://www.flickr.com/photos/70236988@N08/7139432207/" title="TNPcrystal by HNIW, on Flickr"><img src="http://farm9.staticflickr.com/8152/7139432207_bd3c74bc0a.jpg" width="500" height="375" alt="TNPcrystal"></a>

caterpillar - 16-9-2012 at 04:13

Quote: Originally posted by Vikascoder

Could someone help me to nitrate dinitrophenol to trinitrophenol and i have only 70% nitric acid not of further more concentration. (i have other necessary chemicals readily available-)

Convert your diluted nitric acid to K- or Na- salt and mix this salt with sulfur acid.

Bot0nist - 16-9-2012 at 05:52

Killswitch, does it respond well to impact testing (steel + steel)? Are you able to get a melting point? It looks ok.

Ral123 - 23-9-2012 at 01:23

My picric acid didn't detonate in a straw with AP(tetryl did in smaller straw). Looks like it's got some critical diameter. The second test was great. Initiated with AP again and it did great dent for a cardboard charge. How do we make double base detonator with TNP?
http://www.youtube.com/watch?v=1asBOk8_sd8
http://www.youtube.com/watch?v=hopnxUnyxAQ

Kalium - 5-10-2012 at 20:41

Is sodium salicylate a suitable phenol derivative for preparing picric acid?

Ral123 - 5-10-2012 at 21:25

I don't know but I think once I made DNB with sodium benzoate. Well, it was insoluble, burned with a lot of soot and smelled. It took a lot of nitrating mixture trough.

Motherload - 8-10-2012 at 19:11

Kalium
You can always treat the NaSali with dil HCl to get
Sali acid and NaCl so it doesn't interfere with the
HNO3 and H2SO4.
Salicylic acid nitrates to picric acid quite nicely.

[Edited on 9-10-2012 by Motherload]

detonator - 8-12-2012 at 22:23

Use the detonator.
I use the Picric Acid of 1g loading detonator, HMTD of 0.2g as initiator.

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Vikascoder - 9-12-2012 at 00:39

Does picric acid explodes or detonates if we keeps on heating in after confining it

Ral123 - 9-12-2012 at 11:50

Probably will ignite, rise pressure, at high pressure hardly bunrable stuff like picric, tnt and un burns fast, even at high density in closed space. If the case is strong enough above certain quantity you'll surely get ddt.
How is it possible to initiate reliably picric with just 0.2g hmtd, can it be that asa/salicilic gave different more sensitive product. I've heard that cast picric acid needs not just No8 cap, but a booster.

caterpillar - 9-12-2012 at 14:39

Picric acid is slightly more sensitive than TNT. Both of them, been ignited in confinement (large quantities enough), surely will explode. I failed to wake up cast picnic acid, but I used some shit instead of normal primer- Ag2C2 (I had to make double salt- Ag2C2.AgNO3, but I did not know it at that very time). Later I did not try to initiate picric acid, but only its salts- K and NH4 respectively. Ammonium picrate is less sensitive than picric acid, but I had no problems with it, using TATP as a primer. Kalium salt of aforementioned acid burns violently in open air, leaving black smoke, but explodes at nearly smokeless been ignited in confinement.

Ral123 - 10-12-2012 at 01:57

You can't cast ammonium picrate, so why should it be less sensitive then cast picric acid? May be the least sensitive will be ammonium pricrate with tnt cast. Can you share, how did you initiate ammonium picrate with AP?

caterpillar - 10-12-2012 at 05:04

Very simple. I made detonators with 1-2 gr of TATP and it was more than enough to initiate AN + ammonium picrate. I cannot say you why ammonium picrate is less sensitive than picric acid, but according all data what I have it is so. At nearly all ammonium salts are less sensitive than corresponding acids (there is one exception- guess which?)

Ral123 - 10-12-2012 at 09:24

Ammonium nitrite??
I'm interested how exactly you made your insensitive mixture go off with just AP. Did you use thin walled but hard aluminium case, short and fat, pressed at hundreds of kilograms? The opposite, worst case is long and thin PP pipe with thick walls and just stuffed with a stick AP. Also what density was your secondary?

caterpillar - 10-12-2012 at 15:06

Yeah, but I actually thought about nitrate (it explodes, but not corresponding acid). You have a right idea about my detonator. An ordinary pencil was wrapped with aluminum tinfoil (not the thinnest, most likely 0.1- 0.2 mm, I cannot say now). TATP was pressed with same pen. During that process I kept my face far from that pencil and its possible trajectory. Then fuse was insert there and fixed. But if you have some picric acid and on the other hand have prejudgements about TATP, you may use lead salt of picric acid as a primer and pressed picric acid as a buster. I think, 0.5 gr + 2 gr of aforementioned compounds will be enough to wake cast picric acid up. I cannot say nothing about density of my secondary- It was in a simple plastic packet and I pressed it in my fist.

Ral123 - 10-12-2012 at 21:44

I have the feeling that lead picrate has long ddt and no better priming properties then stiphnate. I consider picrates more like for base charge. They have good energy density compared to AP.

pjig - 10-12-2012 at 21:48

Ill be surprised If you make it many more years with your hands intact. Hand pressing sensitive caps the way your describing is downright foolish. Not jabbing at you , but you need to consider a loading devise, and keep your hands away from the loading process.

caterpillar - 10-12-2012 at 23:04

May be. But in fact, my hand was enough far- 20 cm, no closer. I do not think, that I could have been seriously injured during that process. 1- 1.5 gr at that distance may make some trouble only with heavy splinters, which thin tinfoil cannot generate.

caterpillar - 10-12-2012 at 23:07

To @Ralf123: lead stiphnate surely is a better primer compared with lead picrate (but worse compared with lead azide). But if you have only picric acid, lead picrate would be appropriate solution. Try it.

Ral123 - 11-12-2012 at 04:39

I've heard stiphnate is a pseudo primary, along with things like lead nitrophosphite. I'm sure the stiphnate and picrate will be excellent initiators once at maximum velocity.
Does somebody have an idea is it dangerous for picric acid to come in contact with other explosives like AP, or to me mixed with RDX? Can we mix picric acid with for example potassium perchlorate?

caterpillar - 11-12-2012 at 14:10

Picric acid can be safely mixed with TNT, dinitronaphtalene or similar neutral compounds. But never mix it with salts- picric acid is relatively strong acid an in contact with compounds like AN trace amount of nitric acid surely occurs. If you want to mix it with oxidizers, convert picric acid to its ammonium salt. Some mixtures of picric acid was in use during WWI and WWII. Shellite for example (picric acid + some dinitrophenole or mononitrophenole) or russian alloy- picric acid + dinitronaphtalene.