Sciencemadness Discussion Board

Cocrystalization

underground - 6-7-2023 at 16:30

Cocrystalization is a very interesting phenomenon and i have seen not much about this subject on this forum.

From Wikipedia
Two explosives HMX and CL-20 cocrystallized in a ratio 1:2 to form a hybrid explosive. This explosive had the same low sensitivity of HMX and nearly the same explosive power of CL-20. Physically mixing explosives creates a mixture that has the same sensitivity as the most sensitive component, which cocrystallisation overcomes

The intermolecular interactions and resulting crystal structures can generate physical and chemical properties that differ from the properties of the individual components. Such properties include melting point, solubility, chemical stability, and mechanical properties. Some cocrystals have been observed to exist as polymorphs, which may display different physical properties depending on the form of the crystal.

For example, a mixture of hexamine diperchlorate and hexamine dinitrate at 1:1 will cocrystalize forming a new salt with different properties from the original salts. I believe hexamine mononitrate monoperchlorate is created.

The same can be done with cations for example sodium potassium tartate. This is called double salt.

MineMan - 6-7-2023 at 17:20

Done with PETN and ETN it is very interesting I am told, no run aways like PETN and less sensitive then both if I remember correctly from another member

Sir_Gawain - 6-7-2023 at 17:37

Also, it's oxygen balanced with a VoD of around 8500m/s. The P/ETN mixture is probably one of the most powerful explosives easily attainable by the amateur experimenter.

Hey Buddy - 6-7-2023 at 18:00

I have browsed papers on cocrystallization but never looked into them. What is the technique? Recrystallizing with moles of each? If that's the case are ternary crystallizations possible?

In searching im seeing a lot of ultrasonic solvent evaporation techniqes, it claims cocrystallization aside from previous mentionings in thread also causes homogenous crystals largely free of defect for increased handling. Is ultra sonic necessary? What about just dissolving solvent with stirring or using spraying of solvent on cold water surface or something similar?.

[Edited on 7-7-2023 by Hey Buddy]

greenlight - 6-7-2023 at 20:14

It seems there is a larger proportion of CL-20 to HMX is the usual ratio to create the cocrystal structure.

Here is an excerpt from a 2022 paper that tested acetone, ethanol and ethyl acetate as solvents.

"The preparation of CL-20/HMX cocrystal was carried out at room temperature. First of all, 12 mL solvent was added into 1.1 g ε-CL-20 and 0.37 g β-HMX with a molar ratio of 2:1 in glass vails. Then, cocrystals were prepared by evaporation of solvents at natural rate."

Solvent choice makes significant differences in the final crystalline product structure and properties and that paper found ethyl acetate to give the best results.

Here is the link for it:

https://pubs.rsc.org/en/content/articlehtml/2022/ra/d2ra0373...

There are a few other papers out there, some using single solvents and some using dual solvent methods.

I have also read of other cocrystals of CL-20 with TNT and FOX-7. CL-20 has quite a remarkable ability to create these cocrystals and decent VOD to go with it, it's a shame the cost to manufacture it is so high.

underground - 6-7-2023 at 21:32

Cocrystalization seems very interesting, it may be also possible to create new solid oxidisers as rocket fuels. For example a cocrystalized AN/AP or even AN/ Ammonium Chlorate. I do believe a cocrystalized salt of AN/AC can be made to be used as an oxidizers in rocket propellants. You may believe that AC is too dangerous but the cocrystalized salt has complitely different characteristics from the original salt. For example 80/20 cocrystalized AN/AC maybe superior to both since it may be more easily combustible be phase stabilized and be less hydroscopic (if it would be hydroscopic at all) It will most likely outperform AP in ISP.
Even AN/AP cocrystalized would be better from AP since it will be cheaply more environmentally friendly (less chlorine gas) with better ISP since Nitrogen is lighter than chlorine.

Also for energetics, the list is limitless

Guanidine/urea/biuret/diaminourea/ethylene diamine/piperazine/hexamine nitrate/chlorate/perchlorate/pursulphate/periodate/picrate/trinitrobenzoate and the list goes on

Another interesting energetic would be cocrystalized Nitroguanidine with ETN



Below is an example of cocrystalized TNT with CL20

j_ntrev-2022-0124_fig_005.jpg - 186kB

[Edited on 7-7-2023 by underground]

Laboratory of Liptakov - 7-7-2023 at 01:23

It is also possible to melt ETN with nitrocellulose. After cooling, a solid, not brittle mass is formed. With a higher melting point. About 20% NC increases the melting point to 90 Celsius. It has been tried. But I don't know the exact values and ratios and properties. The addition of camphor comes into consideration. This could create ETN - celluloid.

underground - 7-7-2023 at 02:50

All nitro compounts, when its OB is relatively good, have a good performane close to 8k vod. The point is to find the easiest nitro compount to synth and alter its properties with cocrystalization. To my mind the easiest nitrocompount are nitrourea, nitroguanidine. Maybe some other easier to synth nitrate salts like biuret dinitrate and diaminourea dinitrate do the job. NU and NQ have good vod but have their drawbacks. The point is to remove those drawbacks with cocrystalization in order to increase stability and apply castability. The point is cocrystalization increase stability while NU NQ are quite insensitive already. So to my mind come cocrystalization with some sensitive nitro compounts like manitol hexanitrate and nitroclycerine. Maybe even a cocrystalization with some primaries like NHN to decrease sensitivity. For example a cocrystalized energetic consisting mostly of NU/NG with nitroglycerine/MHN/NHN to decrease sensitivity and melting point may be a good secondary. Note that some ions can cocrystallize together in any ratio.

[Edited on 7-7-2023 by underground]

Hey Buddy - 7-7-2023 at 04:05

Quote: Originally posted by underground  
All nitro compounts, when its OB is relatively good, have a good performane close to 8k vod. The point is to find the easiest nitro compount to synth and alter its properties with cocrystalization. To my mind the easiest nitrocompount are nitrourea, nitroguanidine. Maybe some other easier to synth nitrate salts like biuret dinitrate and diaminourea dinitrate do the job. NU and NQ have good vod but have their drawbacks. The point is to remove those drawbacks with cocrystalization in order to increase stability and apply castability. The point is cocrystalization increase stability while NU NQ are quite insensitive already. So to my mind come cocrystalization with some sensitive nitro compounts like manitol hexanitrate and nitroclycerine. Maybe even a cocrystalization with some primaries like NHN to decrease sensitivity. For example a cocrystalized energetic consisting mostly of NU/NG with nitroglycerine/MHN/NHN to decrease sensitivity and melting point may be a good secondary. Note that some ions can cocrystallize together in any ratio.

[Edited on 7-7-2023 by underground]


IMO NQ via GuNO3/H2SO4 is the simplest, mist time efficient per yield and resource efficiency of all nitros. I haven't found anything easier. Maybe some of the stuff that requires no acid is easier NAP, TACP, TACN etc. But for high velocity nitro compounds NQ can be produced more efficiently and quickly than most. I am always attracted to any useful advancement involving nitroguanidine for this reason alone.

underground - 7-7-2023 at 04:29

I believe cocrystalization of NQ with a sensitive primary to requce sensitivity of NQ could end up in a very usefull secondary. A 3rd nitrocompound can be added to that mixture to lower the melting point like TNT or ETN

I dunno if cocrystalized liquids with solids like EGDN and PETN after cocrystalization the evaporation of the liquids will stop. In theory they will stop since the liquid EGDN crystalls are "trapped" into PETN crystal structure. With this way the pelting point of the cocrystalized would be reduced drastically.

Cocrystalized NQ/Nitroclycerine may be very interesting.
Or NQ/ETN - NQ/MHN

[Edited on 7-7-2023 by underground]

greenlight - 7-7-2023 at 11:21

"I dunno if cocrystalized liquids with solids like EGDN and PETN after cocrystalization the evaporation of the liquids will stop. In theory they will stop since the liquid EGDN crystalls are "trapped" into PETN crystal structure. With this way the pelting point of the cocrystalized would be reduced drastically.

Cocrystalized NQ/Nitroclycerine may be very interesting."

That is certainly an interesting concept if the two will behave together nicely but I think trying to obtain a cocrystal from a volatile liquid explosive and a solid would be near impossible.

I would be led to believe that it would just form a mass of solid explosive that was "wet" with NG even after solvent evaporation. I
think that if there was any degree of co-bonding achieved there would be some weeping off the EGDN or NG out of the crystal's structure over time but this would depend on the ratio and the quality of the bond achieved with the solid explosive crystal.

Or you could have the evaporation problem you stated and the liquid component leaves the crystal lattice over a period of time.

Another issue could be stress on the nitroglycerin during handling due to it being "trapped" in a hard crystalline mass. We know soaking NG into an absorbent material reduces sensitivity but we have no idea of the properties when it is in a crystal lattice.

It would have great properties density and brisance-wise if it worked but I am quite sure you would just end up with a explosive oil coated energetic powder.

NQ/MHN or NQ/ETN could be good though.







Hey Buddy - 7-7-2023 at 13:32

Out of what's been mentioned, ETN PETN and NQ, ANQ samples on hand if there's something worth testing... I plan to be in lab tonight testing nitrates on proline and isoleucine...

underground - 7-7-2023 at 15:10

Quote: Originally posted by Hey Buddy  
Out of what's been mentioned, ETN PETN and NQ, ANQ samples on hand if there's something worth testing... I plan to be in lab tonight testing nitrates on proline and isoleucine...


At first you could try to melt a 1/1 mixture of NQ/ETN to see if NQ get dissolved in ETN and at what temperature. You can then test its sensitivity and if it can be detonated. If everything goes well we could then increase the NQ ratio to the point where still it could be detonated.

Another way of cocrystaloization is to dissolve both into a solvent and then evaporate the solvent. It has to be done in a way where when crystals start to form, both crystals have to ppt out together.

Sir_Gawain - 8-7-2023 at 09:55

I tried an oxygen balanced melt of ETN/NQ 6/1 and the NQ does not dissolve in the ETN. I tested some that I made by melting them together, then stirring it while it cooled and grinding it up. It has a higher VoD than pure ETN. The problem with combining them is ETN is soluble in alcohol and insoluble in water, and NQ is the opposite.

underground - 8-7-2023 at 12:39

Quote: Originally posted by Sir_Gawain  
I tried an oxygen balanced melt of ETN/NQ 6/1 and the NQ does not dissolve in the ETN. I tested some that I made by melting them together, then stirring it while it cooled and grinding it up. It has a higher VoD than pure ETN. The problem with combining them is ETN is soluble in alcohol and insoluble in water, and NQ is the opposite.


Those are some very good news. It was always a PITA to DDT NQ and it may be the 1st time someone actually DDT NQ at high density. With cocrystalization NQ has its place. Cocrystalization can happen if both of them dissolved each other without any solvent. Have you figured out how much NQ you can dissolve in melted ETN? Mixed solvents can also be made to dissolve both of them like acetone and water or find another solvent that can dissolve both (maybe nitromethane)

The point is to find a sensitive explosive that NQ can be dissolved in it in large quantities. The goal is to use NQ as the main ingredient for a cocrystalized secondary. NQ can be made easily with everyday chemicals (urea and ammonium nitrate) and it has a high VoD

Het Buddy found out that AspNO3 can dissolve a really big quantity of NQ. The main disadvantages of NQ is that it is a PITA to detonate and it is hard to achieve high density. With cocrystalization high density can be achieved. The goal now is to find out a way to sentisize NQ

[Edited on 8-7-2023 by underground]

MineMan - 12-7-2023 at 03:13

Why not nitrate ETN with an excess of sulfuric acid and mix in an amount of guanidine nitrate. Meaning dump the ground ET and Guanidine nitrate mix into the bath at the same time.

Wouldn’t that co crystallize?

My friend did the same for the ETN/PETN co crystal. Both were just dumped in a nitrating bath and a product that looked completely unlike PETN or etn was produced in high yields.

Sir_Gawain - 12-7-2023 at 04:42

It might, but the product would have to be recrystallized and neither alcohol nor water would work. We need to find a solvent that can dissolve a reasonable amount of both compounds.

underground - 12-7-2023 at 05:04

ETN/PETN can be dissolved in Acetone. Both are quite soluble in acetone

[Edited on 12-7-2023 by underground]

Sir_Gawain - 12-7-2023 at 08:59

I meant for the NQ/ETN mixture.

underground - 12-7-2023 at 09:25

Quote: Originally posted by Sir_Gawain  
I meant for the NQ/ETN mixture.


You can just melt each other without any solvent

Sir_Gawain - 12-7-2023 at 11:12

I tried it, and NQ doesn't dissolve in molten ETN.

[Edited on 12-7-2023 by Sir_Gawain]

underground - 12-7-2023 at 12:14

You can try mixed solvents too like water and acetone

Sir_Gawain - 12-7-2023 at 15:39

I don't think it would work. NQ is pretty insoluble in acetone. A solution of NQ in hot water will precipitate upon addition to acetone.

underground - 13-7-2023 at 01:19

There are plenty of solvents out there. Use your imagination. Nithromethane possibly can dissolve both. Methanol ? Isopropyl? Mek? Toluene? Benzene?

dettoo456 - 13-7-2023 at 11:04

@underground NMP or another polar aprotic like DMF and DMSO might work. NQ has been verified to be soluble in NMP and DMSO and if the polarity trend follows, then ETN might be aswell

Hey Buddy - 13-7-2023 at 14:50

Quote: Originally posted by dettoo456  
@underground NMP or another polar aprotic like DMF and DMSO might work. NQ has been verified to be soluble in NMP and DMSO and if the polarity trend follows, then ETN might be aswell


I have a bunch of DMSO used for skin absorption of pharmaceuticals for animals, but Ive never used it as a solvent, is DMSO soluble in water? How would one recrystallize an ETN/NQ cocrystal from DMSO? I could try it


Okay, I tested DMSO in a petri dish. It fully dissolves NQ quickly with stirring around 30 C. Same with ETN. Adding water drops out a fine white suspension. I would assume the DMSO is miscible with the water and it is very fine NQ/ETN coming out of solvent. if thats the case, it's pretty awesome. I suppose the DMSO/water can be washed away from precipitate in a filter. I assume DMSO is unreactive with any of the common energetics. , should wash away without too much is issue. It is like a thin gel at 20C and becomes a little thinner at 30 C, it becomes very thin when water is added. Why is DMSO not used in energetics more often? I suppose it is expensive but not outrageous.

I will try NQ in a 1:1 mole ratio with ETN. The dump it into water and see how it filters...

[Edited on 14-7-2023 by Hey Buddy]

Hey Buddy - 13-7-2023 at 17:49

48 mmol DMSO dissolves 48 mmol of ETN/NQ. It took about 15 minutes at 30C stirring 311rpm to dissolve. It could likely take more ETN/NQ with an increased stir time. I'm not going to add more but I think it would handle more. Going to drop water into solvent 1:1 or until precipitation then vacuum filter and wash with water. It is ~2.5g NQ to 7.25g ETN.

Hey Buddy - 13-7-2023 at 18:44

It appears to work. There is a uniform crystal of a little smaller than table salt, and the volume of the two materials as a cocrystal is considerably reduced. The dmso requires a massive amount of water to wash out. I at first used equal mass dmso to water which caused some precipitation, but it first comes out like a syrup. So I kept it on stirring and added as much water as would fit in the beaker. The filtered, put back in a beaker, added more water, stirred decanted, rinse, repeat. It would be better to dissolve in a small beaker then dump in a large beaker of water while stirring. Any dmso that isn't diluted enough water holds the dissolved EM like a gum. DMSO cause anything dissolved to be directly absorbed through the skin into the blood stream so gloves are absolutely necessary when using dmso. I would consider it a bit hazardous for that reason, but if precaution is used it seems to be incredibly effective at creating a dense cocrystal.

UPDATE: After looking at this the next day, there is definitely still two materials. The DMSO made them smaller in volume and there is some cocrystallization, but only partial. Not a homogenous cocrystal, I don't know much about crystallization theories. Perhaps it is favored at some lattice ratio interval, and the favored ratio is cocrystallized while the excesses rejected. Regardless, dmso does dissolve both ETN and NQ. I think aspNO3 actually made denser NQ but it was dissolved at higher temperature.

[Edited on 14-7-2023 by Hey Buddy]

Sir_Gawain - 19-7-2023 at 10:42

Besides DMSO, most solvents seem to work for only ETN or NQ. Perhaps though, we could use that to our advantage. I could try crashing a solution of ETN in methanol into NQ in hot water, or vice-versa. Even with strong stirring it probably would just separate into two layers that slowly crystallize their respective solutes. And even if it did work, I couldn't imagine it having a great density.

[Edited on 19-7-2023 by Sir_Gawain]