nitroglycerin

That stump from a few posts ago, which was not removed, was blasted recently with a 400g charge of nitroglycerine powder containing 10% NG. The blast was successful and the two pieces of the stump still in the ground are each attached by a single large root and can be wiggled by hand easily. A set of come alongs will be able to pull them out by anchoring to a nearby tree. A higher velocity dynamite or a larger charge would have removed the stump completely. I have found that once they are blown apart like this, however, that the remaining pieces are very easy to pull out of the ground.

You can see in the last picture the aluminum casing from the failed urea nitrate charge. It was actually a fairly difficult stump to blast because of the very large roots which were very spread out and well anchored and with large holes between them for the explosive gases to escape through.




[Edited on 10-10-2014 by Hennig Brand]

Quote: Originally posted by Hawkguy

As to the idea of making small Nitroglycerin charges, I've found that most commonly people soak NG into Ammonium Nitrate or similar. Is it possible to soak NG into a TNT mixture?

The stump pieces were in fact easily removed. A four wheel drive Toyota Tacoma was used to pull out the two remaining large pieces of the stump. Roots are similar to guy-wires; when there is only one guy-wire the wood is no longer well anchored to the ground and can be easily removed. Also the blast tends to heave the pieces at least a bit, removing tension from the guy-wires/roots, which also weakens the roots hold on the ground facilitating removal.




[Edited on 27-10-2014 by Hennig Brand]

synthesis large quantity nitroglycerin

Hi Bert

I already went through many posts here , maybe i dropped the correct ones.

I am really talking about large quantities , something over 1 Liter.

You want advice and pro tips on how to make over 1 l of nitroglycerin as a single batch.

I am going to have to formulate a proper response to that, as regards your safety and forum policy- that may take me a while. I do not type accurately with tachycardia.

Of course it can be done, and relatively safely too, by people who are experienced. It was routinely made in ton quantities in batch processes industrially from what I understand. The risk factor increases sharply with increasing batch size, however, and even the pros did have occasional accidents. There is no way for someone experienced to write you a simple procedure that is going to account for every possible eventuality or give you the situational awareness that they would have. I would advise that you stick with smaller batches and just make more of them if you need more NG. I think the most I ever made was 250mL in a single batch. Cleared up any deficits in attention that I had, at least while performing the synthesis.

Is making large batches really worth it to you? If it is, start small and develop a good working understanding of the process and the dangers involved first.

The processes involved are relatively simple, but there are very real hazards.

Sometimes the way a question is asked shows the questioner has not yet done enough research.

Take a look at my post on this same page, see the links to two books in sciencemadness.org library.

Naoum' book details industrial equipment and reagents used for every scale- From bench procedure suited to students/material testing lab, pilot plants and full scale factory layouts for 1,000's of kg. Along with historical development of such procedures and mention of not a few deadly accidents.

Tenney Davis gives lab bench scale synthesis and describes commercial production and handling, including continuous process machinery.

I warn you: Batch size in such reactions can not be scaled linearly with safety. If you try your 5ml process at 200 X size, you will likely experience a runaway, and may well be injured or killed.

When scaled up:

Volume (and heat production!) goes up as a cube.

The surface area (area needed for heat to escape!!!) goes up as the square.

It is very possible to set yourself up with a batch size and reagent addition profile where no amount of external cooling will save you.

Note that even the smallest glycerin testing batch sized apparatus detailed in Naoum has circulating chilled water cooling? It is not there for swank.








[Edited on 9-1-2015 by Bert]

Nitroglycerine in Large Batches

Quote: Originally posted by Hennig Brand

Just realized I messed up the calculation for the amount of ice needed on the last page of this thread. The amount of ice required was based on the mass of glycerine nitrated, assuming complete nitration, and I calculated as if it was based on the amount of NG. Quote: Originally posted by Hennig Brand   An ice water bath is an excellent way to cool a nitroglycerine nitration reaction mixture. Water heat of fusion: 334J/g (334kJ/kg) Mass of ice needed for cooling per gram of glycerine nitrated assuming no heat transfer to surroundings: (1.43kJ/1g Glycerine) * (1kg Ice / 334 kJ) = 0.0043 kg Ice/1g Glycerine Nitrated (4.3g Ice/g glycerine nitrated) Ice needed for synthesis of 1L of NG = 1000mL(1.6g/mL)(4.3g Ice/g glycerine) = 6880g of Ice (6.88kg of Ice) This is assuming no heat transfer from the surroundings! In reality the amount of ice required could be much more. Here is the correction: An ice water bath is an excellent way to cool a nitroglycerine nitration reaction mixture. Water heat of fusion: 334J/g (334kJ/kg) Mass of ice needed for cooling per gram of glycerine nitrated assuming no heat transfer to surroundings: (1.43kJ/1g Glycerine) * (1kg Ice / 334 kJ) = 0.0043 kg Ice/1g Glycerine Nitrated (4.3g Ice/g glycerine nitrated) Ice needed for synthesis of 1L of NG = 1000mL(1.6g/mL) / (227.09 g/mol) * (92.09382 g/mol) * (4.3g Ice/g glycerine) = 2790g of Ice (2.79kg of Ice) This is assuming no heat transfer from the surroundings! In reality the amount of ice required could be much more. What a difference a little slip can make!

As Bert was saying volume increases much more quickly than the outside surface area of the vessel. A sphere is considered as an idealized representation of a round bottom reaction flask, full of nitration mixture. In reality it would only be partially full and would have an open top and very likely a flat bottom in most cases, but the following is just an approximation.

Volume of Sphere = 4/3 * pi * r^3
Surface Area of Sphere = 4 * pi * r^2

If the radius, or diameter, is doubled the volume of the spherical vessel increases by eight time (2^3 = 8), while the outer surface area only increases by four times (2^2 = 4). If we increase the diameter by three times, we get 27 times the volume and only 9 times the outer surface area. Since heat produced is directly proportional to the volume of the reaction mixture and in most amateur settings reaction cooling takes place through the side walls of the reaction vessel, it is very important to make sure that adequate cooling is provided for.

I worked through the numbers a bit this morning, because I became interested myself.

The heat evolved in a nitration reaction includes not only the heat of nitration but also the heat of dilution. If the nitration reaction temperature is allowed to rise too high, oxidation processes can start to take place which are very exothermic and can quickly lead to uncontrollable runaway reactions. If this starts to happen the nitration mixture must be immediately drowned in cold water to stop the reaction. In small scale NG nitrations, runaway reactions are normally fairly benign, but as the surface area to volume ratio of the reaction mixture gets smaller (larger batch) a runaway reaction can be very dangerous often resulting in explosion if the reaction mixture is not promptly drowned in water.


Heat of Nitration
"According to information from different sources the heat of nitration of glycerol to trinitroglycerine varies from 120 to 170 kcal (ca. 502 to 711 kJ) per 1 kg of glycerine." (Urbanski Vol. 2 pg. 46) The higher value of 711 kJ / 1 kg of glycerine will be assumed, for the heat of nitration, as a worst case type of scenario.


Assume starting with pure glycerine, 95% HNO3 and 95% H2SO4. Assume the following composition for the mixed acid:

HNO3....40%
H2SO4...55%
H2O.......5%

Assume 6.5 parts by mass nitration mixture per part of glycerine will be used.

Per 1g Glycerine:

Pre Nitration Numbers:

HNO3: 0.4(6.5g) = 2.60g
H2SO4: 0.55(6.5g) = 3.58g
H2O: 0.05(6.5g) = 0.33g
Total mass = 6.51g

Percent by weight of total acid: 95%
Percent HNO3 based on anhydrous acid: 42%
Enthalpy of mixed acid solution estimated from attached graph: -86kJ/kg


Post Nitration Numbers:

Per 1mole of glycerine nitrated, 3 moles of HNO3 are consumed and 3 moles of water are produced.

HNO3: 2.60g - 2.053g = 0.547g
H2SO4: 3.58g
H2O: 0.33g + 0.5864g = 0.916
Total mass = 5.04g

Percent by weight of total acid: 82%
Percent HNO3 based on anhydrous acid: 13%
Enthalpy of mixed acid solution estimated from attached graph: -254kJ/kg

Heat of Dilution
Heat of dilution = [5.04g / 1000g/kg * (-254kJ/kg)] - [6.51 / 1000g/kg * (-86kJ/kg)]
Heat of Dilution = -0.72kJ/1g Glycerine Nitrated

Total Heat Produced
Total Heat Produced = Heat of Nitration + Heat of Dilution of Mixed Acid
Total Heat Produced = -0.711kJ/1g Glycerine + -0.72kJ/1g Glycerine
Total Heat Produced = -1.43KJ/1g Glycerine

The nitration of glycerine is an extremely fast reaction, typically about 80% of the glycerine can be nitrated in less than one second according to Urbanski Vol. 2. The associated section, discussing this, from Urbanki was snipped and made into a pdf which is attached. Assuming vigilant temperature monitoring and good agitation/mixing, all that need be done to accurately control the temperature is to very carefully control the addition rate (assuming the ambient temperature isn't a lot above room temperature). Good cooling makes the process much safer and certainly much faster, however, since the reaction does produce a lot of heat which needs to be removed. As the batch size gets larger it quickly becomes impractical and dangerous to not have powerful cooling in place.

Heat Capacity of the Reaction Mixture
The ability of the reaction mixture to absorb heat was examined.

From Engineeringtoolbox.com:

Specific Heats:

Sulfuric Acid: 1.38kJ/kg.K
Nitric Acid: 1.72 kJ/kg.K
Water: 4.19kJ/kg.K

Nitroglycerine: 1.7814kJ/kg.K (A Dictionary of Applied Chemistry)

The post reaction mixture was used in the calculation. Interactions between species were neglected, so as to provide a simple approximation of the heat capacity of the mixture.

Average Heat Capacity of post reaction mixture = 0.547g/7.5089g(1.72kJ/kg.K) + 3.58g/7.5089g(1.38kJ/kg.K) + 0.916/7.5089g(4.19kJ/kg.K) + 2.4659g/7.5089g(1.7814kJ/kg.K)
Heat Capacity of post reaction mixture = 1.860996kJ/kg.K

Assuming no heat dissipation, for -1.43kJ heat produced per 1g glycerine:

deltH = m * Cp * deltT

Temperature Rise Assuming No Heat Dissipation = deltaT
deltaT = 1.43 kJ / [(1.860996kJ/kg.K) * (7.5089g/1000g/kg)]
deltaT = ca. 102K (102C)

Without adequate heat removal, the temperature of the reaction mixture could easily climb to very dangerous levels and this gets more complicated/difficult as the reaction mixture gets larger.

An ice water bath is an excellent way to cool a nitroglycerine nitration reaction mixture.

Water heat of fusion: 334J/g (334kJ/kg)

Mass of ice needed for cooling per gram of glycerine nitrated assuming no heat transfer to surroundings:

(1.43kJ/1g Glycerine) * (1kg Ice / 334 kJ) = 0.0043 kg Ice/1g Glycerine Nitrated (4.3g Ice/g glycerine nitrated)

Ice needed for synthesis of 1L of NG = 1000mL(1.6g/mL)(4.3g Ice/g glycerine) = 6880g of Ice (6.88kg of Ice)
This is assuming no heat transfer from the surroundings! In reality the amount of ice required could be much more.


Very close temperature monitoring, glycerine addition control, excellent mixing and excellent cooling are all very important.

Good agitation/mixing keeps the temperature differential on either side of the vessel side wall at near maximum resulting in a near maximum rate of heat transfer/rate of cooling. Good agitation also prevents localised hot spots which can/will result in exothermic decomposition (oxidation processes) which could easily result in uncontrollable temperature rise/runaway.

Remember to get lots of ice before proceeding with the nitration, especially if it is a larger scale batch size.

Remember to keep the temperature below 30C. Actually, keeping the temperature well below 20C is safer and according to Urbanski these lower temperatures normally produce higher yields as an added bonus for staying farther away from the dangerous, higher temperature, region.



Attachment: Nitroglycerine Nitration Reaction Rate from Urbanski Vol. 2.pdf (184kB)
This file has been downloaded 661 times

Attachment: Heat Effects Due To Dilution During Aromatic Nitrations By Mixed Acid In Batch Conditions.pdf (324kB)
This file has been downloaded 592 times




[Edited on 12-1-2015 by Hennig Brand]

[Edited on 14-2-2015 by Bert]

Hi Bert and Hennig,

This is a photo for the reaction vessel for NG at Nobel's first company.



for me it looks horrible , I took the picture from BBC documentary video, here is a link for this part : http://youtu.be/01pjt_K-94M?t=33m16s

It scare me when you talk about metal vessel for the reaction because we use conc Nitric or Sulfuric acid.

I always try to keep the reaction temperature between 0 to 5 degrees to be on the safe side.

I always use 5 times the amount of NG for synthesis as a rule of thumb.

it is really interesting to know how large scale production of NG works.

[Edited on 12-1-2015 by ecos]

[Edited on 12-1-2015 by ecos]

Hi Hennig,

I modified the picture, it should be better now for your screen/

your last statement was mentioned in the youtube link i provided above , i wonder how a man can sleep while he is synthesizing NG , he would loose his life for sure.
what interest me is the size of the reaction vessel and the valves !!

I wonder how would he control the situation if the temperature starts to increase gradually without stopping , he would need a bigger container full of ice or even KOH to stop the run out !

safety precautions is a point of interest here.

The following snip-it was taken from, "Lectures on Explosives" Third Edition (1902) by Willoughby Walke. There are other types of Gelignite as well such as ammon gelignite.





I don't think I have seen a video, but I haven't really looked for one either. Basically the gelatine and dope are prepared separately and then the two are well mixed. The gelatine can be much easier formed by using a bit of acetone, I have found, and then later allowing the acetone to evaporate. The dope is well dried and powdered before mixing with the gelatine. It is a very simple process for the most part.

Apparently ammon gelignites replaced regular gelignite for the most part.


[Edited on 13-1-2015 by Hennig Brand]

nice to know about this mixture, I always use this mixture:
90% NG
9% NC
1% Sodium bicarbonate as anti-acid, (Naoum used chalk in his book but i use sodium bicarbonate , not sure if i do the correct thing )

i hope if there is a video for the process

Quote: Originally posted by Hennig Brand

I think it might be playing with fire a little bit, so to speak, but as long as the addition rate was carefully controlled, and the temperature was closely monitored, I don't see any problems other than the process taking longer than if all the high powered cooling equipment were installed. With good agitation glycerine doesn't hang around in the nitration mixture and then all react at once like sometimes happens with other nitrations. Glycerine nitrates very quickly and completely even at very low temperatures. The reactions are very exothermic, however, and the temperature must be watched like a hawk and additions must be slow and controlled. A big bucket of cold water must be handy to drown the reaction if controlling the temperature becomes impossible (which should only happen if the process was rushed and/or there was a lack of cooling for the size of the reaction). Obviously the bigger one goes the more dangerous it becomes, especially if there is a lack of understanding about the process. That glass apparatus above is very neat, but I don't think it is necessary for 200g or so of NG. It would probably be very convenient though. I have made about a cup (~250mL) of NG before in a glass coffee pot. Other than my nerves it all went fine. It took a good couple of hours to add all the glycerine, though, and I was stirring with a glass rod by hand (I now only swirl for safety). It wouldn't be very hard to rig up a Teflon paddle driven by a cordless drill (powered by a mains fed power supply). With a good ice bath or salt ice bath and the Teflon paddle working vigorously cooling should be fantastic through a thin walled glass round bottomed vessel. Thermal Conduction Through Glass I think you have a point about the different materials and thermal conductivity, but I don't think it is as much of an issue as you think at these small scales. Thermal Conductivities Borosilicate Glass: 1.14w/m.K (camglassblowing.co.uk) Stainless Steel: 16w/m.K (Engineeringtoolbox) Lead: 35 w/m.K (" ") Carbon Steel: 43w/m.K (" ") Cast Iron: 55w/m.K (" ") So yes, glass really stinks in the thermal conductivity department. However, I still don't think it is much of a problem at the scales we are discussing. From the reaction numbers in the last post, a 1L reaction mixture can accommodate the nitration of about 247g of glycerine. The spherical vessel will be assumed to be twice as large as needed and only using half its surface area for cooling to the ice bath. Q/t = [K * A * (TH - TC)] / d Heat conduction/time = [Thermal conductivity * Area * (Temperature hot side - Temperature cold side)] / Thickness of sidewall Assume that a 15C temperature differential is maintained. Just measured a coffee pot and it was 2mm thick or less; will use 2mm wall thickness. Q/t = [1.14w/m.K * 0.03838m^2 * (25C - 10C)] / (0.002m) Q/t = 328watts or 328J/s Total Heat Produced = 247g Glycerine * (1.43kJ/1g Glycerine) = 353kJ Time needed to transfer all heat using a 15C temperature differential = 353kJ / (0.328kJ/s) = 1077s or 17.9minutes As long as the temperature differential was maintained at least 15C from one side of the glass sidewall to the other, 247g of glycerine could be nitrated, producing about 500g of NG, and the heat produced could be transferred in less than 18 minutes. I can see how this is maybe starting to push the limits, however, a much greater temperature differential could be maintained which would increase the rate of heat transfer. One of the important points to take note of; if a vessel with low conductivity, such as one made of glass, is used the ability to deal with a temperature/energy surge is less. [Edited on 12-1-2015 by Hennig Brand]

Quote: Originally posted by Hennig Brand

In case anyone was interested here are the equations for one dimensional, steady state, heat conduction for a cylindrical layer as well: Q/t = (T1 - T2) / Rcyl Rcyl = ln(r2 - r1) / (2 * pi * k * L)

Quote: Originally posted by Hennig Brand

I think that mixture is normally referred to as blasting gelatine, though I see on the internet the terms gelignite and blasting gelatine often seem to be used interchangeably. Gelignite is a high gelatine content dynamite with an absorbent dope of powdered nitrate and fuel from what I understand.

Volume & Area Equations for Partially Filled Spherical Vessels

Hi Hennig,

I always go through your equations and got lost easily , As I understand you try to calculate the heat transfer or heat generation due adding NG with acids into ice ! , your first equations says we need ice with volume at least 6 times the volume of mixture (NG + acids)

I didnt see any equations showing the required temp of ice+water!.
if someone used water with temp = 5 degrees instead of ice, would that be risky ?

If you have ENOUGH cold water, and the reaction vessel configuration and rate of addition allow the heat to be removed, it will be possible to prevent a run away. Determining in advance HOW MUCH ice and WHAT SHAPE/SIZE reaction vessel is what all the engineering math earlier was about. You only need to keep the charge below someplace around 20 C, but colder gives more margin for error-

The key difference in starting with cold water: there is a substantial amount of energy required to MELT the ice. You're going to need substantially MORE cold water than ice, even comparing liquid water at .001 ºC, to solid ice at -.001 ºC.

Water heat of fusion: 334J/g (334kJ/kg)

See area "B" of graph below:






The diagram shows the uptake of heat by 1 kg of water, as it passes from ice at -50 ºC to steam at temperatures above 100 ºC, affects the temperature of the sample.
E: Steam absorbs heat and thus increases its temperature.

D: Water boils and absorbs latent heat of vaporization.

C: Rise in temperature as liquid water absorbs heat.

B: Absorption of latent heat of fusion at 0 ºC,

A: Rise in temperature as ice absorbs heat.

from-http://www.physchem.co.za/Heat/Latent.htm

[Edited on 6-2-2015 by Bert]

ok , i got the message thanks all

I always nitrate glycerin at 5 degrees, so it would be an advantage to cool it more before pouring it in the ice path.
they state in referencing "the mixture is added in one portion to crushed ice" or "the mixture was added to ice path in one shoot"
why they use the wording : "one portion or one shoot" ?

[Edited on 6-2-2015 by ecos]

Quote: Originally posted by Hennig Brand

The nitration mixture will be stirred with a Teflon paddle powered by drill.

Overhead stirrers can also be run so that they don't contact the sides or bottom of the reaction vessel, which can be an advantage in safety with friction sensitive materials.

I don't think there needs to be any mess. If there is significant splashing it likely means the stirrer is going too fast or the stirring paddle, or other attachment, is not of the right type or some other mix-up. Cordless drills can be modified for accurate speed control easily, since they use a DC motor. They can also be made to run from a mains fed power supply. Even regular corded drills normally have brushes, as far as I know, so they too can be easily speed controlled by simply changing the voltage supplied to them or better yet using a triac type speed controller. I found a hobby speed controller circuit here:
http://www.electroschematics.com/444/motor-speed-regulator-w...

"This triac-based 220V AC motor speed controller circuit is designed for controlling the speed of small household motors like drill machines. The speed of the motor can be controlled by changing the setting of P1. The setting of P1 determines the phase of the trigger pulse that fires the triac. The circuit incorporates a self-stabilizing technique that maintains the speed of the motor even when it is loaded.


220VAC Motor Speed Controller Schematic




For example, when the motor of the drill machine is slowed down by the resistance of the drilled object, the counter-EMF of the motor also decreases. This results to a voltage increase in R2-P1 and C3 causing the triac to be triggered earlier and the speed increases accordingly."


[Edited on 9-2-2015 by Hennig Brand]

Quote: Originally posted by Hennig Brand

An ice water bath is an excellent way to cool a nitroglycerine nitration reaction mixture. Water heat of fusion: 334J/g (334kJ/kg) Mass of ice needed for cooling per gram of glycerine nitrated assuming no heat transfer to surroundings: (1.43kJ/1g Glycerine) * (1kg Ice / 334 kJ) = 0.0043 kg Ice/1g Glycerine Nitrated (4.3g Ice/g glycerine nitrated) Ice needed for synthesis of 1L of NG = 1000mL(1.6g/mL)(4.3g Ice/g glycerine) = 6880g of Ice (6.88kg of Ice) This is assuming no heat transfer from the surroundings! In reality the amount of ice required could be much more.

Quote: Originally posted by Hennig Brand

I was planning an using a piece of Teflon sled runner, which would act like a large stir bar except that it would be driven from above by shaft and not from below by magnetic coupling. I already have a powerful cordless drill and power supply and speed control for it, so that much is sorted out. Did you have any suggestions about the type of mixer attachment that would be suitable? I would be pleased to hear any.

I would use propellers that would induce much trubulence at low speed.
Like multiple propeller blade on a single axis or cheese slices (with holes with different paterns and size to break laminarity on next coming mixing wall)



Or something more complex...like



But I think complexity is not needed here.

I like this shape, made from HDPE. Should replace metal shaft with Teflon or glass for use in nitration mixtures- Spin in direction that causes fluid to be drawn in from top & bottom, expelled from sides (clockwise as seen from above).

Quote: Originally posted by ecos

So whats wrong about magnetic stirrer? http://en.m.wikipedia.org/wiki/Magnetic_stirrer

Homemade Overhead Stirrer

Thanks for the ideas. For now I am going to try and use what I have lying around though.

It isn't beautiful, but it is a good working homemade variable speed overhead stirrer with lots of power and speed. Total cost ca. $26.60 ($10 for second hand 18V cordless drill, ca. $15 for 10mm diameter Teflon rod & $1.60 for mounting hardware). Often times drills in nearly perfect shape like this can be found very cheap or free because the batteries need replacing. It is often more cost effective to simply buy a whole new drill kit than to replace just the battery or batteries. I discovered that cordless drills have very good speed control; all that is required is a way to precisely control the trigger position. The trigger position controls the position of a variable resistor in the pulse width modulator trigger module. The drill also has a high and a low speed setting on the gear head. A c-clamp was found in the junk pile which was originally designed to hold a half ton truck cap on. The c-clamp works very nicely for setting and maintaining trigger position and speed. The trigger mechanism (pulse width modulator) was removed from the drill. A section of regular household extension cord (3m long) was spliced in as an extension between the trigger mechanism (pulse width modulator) and the drill. The useless cells were removed from the battery pack and the pack casing was mounted to the vertical member of the stirrer stand; the drill can be easily attached and removed in this way. The drill is rated as 18V, but works fine from 12V providing all the speed and power needed. The pulse width modulator is rated for 9-24V and 12A. A computer power supply rated for 12V and 12A was used to supply power to the PWM. The stirring blade or paddle is put in the 2L flask lengthwise then turned sideways and threaded to the rod. A much larger paddle can be put through the neck of the 2L flask in this way. Two stirring blades were made which can both be threaded to the end of the rod together if desired. The Teflon rod has a slight bend to it, so I will be looking for something better such as a steel rod coated with Teflon or HDPE. I would imagine that HDPE plastic tubing could be used to coat or slide over a straight steel rod. A tight friction fit where the rod and paddle are threaded together could make a decent seal and prevent acid from reaching the steel rod. It is very easy to form a vortex, even at about medium speed, but the bent shaft makes higher speeds unstable. The blade is also not balanced which could be a problem at high speed. When both blades are attached together they can be installed so that there is better balance.

BTW, the "Teflon sled runner" that I obtained from a scrap yard is actually HDPE (determined by density). Checking density is a good way to help determine what type of plastic one has if it is found as salvage and the identity is uncertain.

A plastic shield could be attached to the shaft, close to the chuck, to prevent most acid vapors from reaching the drill. An exhaust fan with the inlet positioned just above the flask neck would also help prevent acid vapors from reaching the drill.





[Edited on 20-2-2015 by Hennig Brand]

Looking at the common stainless steels, it appears as though none are ideally suited for contact with nitration acid though 304 is fair according to several compatibility tables. I picked up an 18 inch long piece of 3/8 inch diameter 304 SS from a local machine shop for about $3. The end of the SS rod was threaded with a die. The HDPE stirring paddles were drilled and tapped and made balanced by cutting off the bottom lip that the Teflon rod was threaded into earlier. With the relatively straight rod and balanced blade the stirrer can be run at high speed now with only minimal vibration.

The 304 SS will corrode in the mixed acid, but the rate should be very slow especially at the low temperatures of a nitric ester nitration. HDPE is also not an ideal material for nitration mixtures, but it too should degrade relatively slowly especially at the low temperatures of a nitric ester nitration. Also, the contact time is normally fairly brief since nitric ester nitrations are normally relatively rapid.

Here are a few pictures. The flask is 2L and contains water. The last picture is of the stirrer running at about 80% of full speed.




[Edited on 20-2-2015 by Hennig Brand]

Found a decent compatibility table with lots of information for nitration acids in contact with different stainless steels at various concentrations and temperatures. From this table it looks as though 316SS is actually better than 304SS is some cases, though both appear to be very good at low temperatures.

The pdf containing the compatibility tables is attached below. The ratings include a general corrosion rate as well.

"
0 = resistant to general corrosion (mass loss rate <0.1 g/h · m² corresponding to a corrosion rate < 0.11 mm thickness reduction/year)
1 = slight susceptibility to general corrosion, suitable for some applications (0.1 – 1.0 g/h · m² corresponding to 0.11 – 1.10 mm thickness reduction/year)
2 = low resistance to general corrosion, unsuitable for virtually all applications (1.0 – 10.0 g/h · m² corresponding to 1.1 – 11.0 mm thickness reduction/year)
3 = no resistance to general corrosion (>10.0 g/h · m² corresponding to > 11.0 mm thickness reduction/year)
The following warning is provided for the major forms of localised corrosion
L = risk of pitting, crevice corrosion or stress-corrosion cracking, even in resistance class 0
"

A jpg of the nitration acid part of the table was made as well. Column 4 and 5 refer to 304 and 316 stainless steels respectively.



Attachment: Material Compatibility Tables.pdf (213kB)
This file has been downloaded 649 times

Kind of like this?

Hi Bert,

I start to feel that you like this figure a lot

Quote: Originally posted by Bert

Kind of like this?

We only use 316L SS for the internal wetted parts of our pharmaceutical tanks after we double weld the seams and dress and sand them then we have to polish them to .4 RA (mirror finish) after its given the ok by the inspector its passivated internally to smooth the surface off even more, then you get the tank back in 6 months to a year to referb it cause the dumb factory workers use metal mixing poles and scratch the inside up . nuxy.

304 Stainless Steel and HDPE Held Up Well In Nitration Acid

I will just give a brief description here and possibly later something more thorough with more pictures in an ETN thread. A mixed acid was made from 600g of ammonium nitrate, 900mL of 91% sulfuric acid and was used to nitrate 150g of erythritol in a 2L flask. Mixing was provided for nitration, dilution and washing stages by the previously built overhead stirrer. The HDPE blade and 304 SS shaft were in contact with the mixed acid for about 2 hours and there appears to be no visible damage whatsoever. The tool marks, which are visible in the picture, are the result of my sloppy work earlier during construction. The temperature of the nitration never went above 15C which is ideal from a corrosion prevention perspective.

Addition of the 150g of erythritol was done over the course of about 30 minutes. No supplemental cooling was used. The ambient temperature was about -5C, which is a different situation entirely from performing the reaction in the summer with an ambient temperature of +30C for instance. Using this type of mixed acid and coarse crystals of erythritol (about the size of granulated white sugar) this reaction is very easy to control; very slow and gentle if a little care is used. Supplemental cooling or slower erythritol addition would be required in a hotter environment.

It is very possible, and would not be much more difficult, to make a pound of ETN at a time with this arrangement. A 3L or larger flask should be used, however, and a 20L pail should be used for dilution and washing as well.







[Edited on 4-3-2015 by Hennig Brand]

Impressive batch and a very cool stirrer system What was your yield if you don't mind me asking? I've never scaled an ETN synthesis to this level and it would be interesting to know how it looks in terms of process yield.

Thanks, I know that you like making equipment too. If I know you though, construction would likely have been a little neater.
Still drying the product, but I will take a dry crude weight before recrystallization and post it here. I lost at least a small amount during filtering. Regular coffee filters aren't really practical at this scale, so a cloth filter (piece of old undershirt) placed in a large colander was used. During filtering, it is the material which builds up on the membrane that does most of the filtering not the filter membrane itself. When I first started filtering some fines went right through the filter, but once a small amount built up over the larger holes almost none passed through (only clear liquid could be seen passing). The correct procedure would have been to collect what passed through the filter until the filtrate was clear and then pass the filtrate which was collected up until then back through the filter to collect any fines that initially passed through. The yield still looks pretty good and it won't be long until it is dry.

I'm not a fan of loose wire bundles...that much is true
But then again I certainly do lack the capacity and determination for achieving perfection. Preferences may vary wildly and in the end functionality is the real judge of success, I guess...
Btw, are you drying your batch before recristallisation? I've found this practice to be unworthy and a waste of time in case etn is involved. One can just squeeze the batch more or less dry between paper towels or other suitable absorbant media and then go on dissolving it in preheated alcohol of choice. Works like a charm and is a great time saver...not to mention the slightly raised safety of handling a damp batch...and it will not spill so easily as it sticks together in the damp state.

[Edited on 4-3-2015 by markx]

It's a work in progress.
What I thought I was seeing, a long time ago, was that even small amounts of water significantly reduced the methanol's ability to dissolve the crude ETN (ETN has very low solubility in water). Even slightly damp crude ETN can hold a surprisingly large amount of water. Also, knowing the dry weight makes it easier to accurately determine the amount of solvent needed for the recrystallization to follow. It is something to consider though, since it is a pain to dry the crude product, which is very fine and not as crystalline, clumpy and with more hydroxyl groups left unnitrated as well as at least a small amount of acid contamination which all make drying more difficult. The recrystallized material is always much easier to dry I find.


[Edited on 4-3-2015 by Hennig Brand]

Equilibrium moisture content finally appears to have been reached. Here are a couple of pictures of the dry crude yield. From 150g of erythritol, 240g of crude ETN was obtained.

The crude product was recrystallized, but it will need time to dry. The 240g of crude product was added by the spoonful to about 720mL of methanol which was previously brought almost to the boil. With the exception of a sub gram quantity of solid material all material dissolved within seconds. A hot filtration was performed, but because of the simple filtration apparatus and a -15C ambient temperature rapid cooling caused the filter to clog when the process was only about 2/3 complete. Nearly all material was recovered in spite of this, but it was inconvenient to say the least. There is a big difference between processing 24g of ETN and 240g! I need to develop more finesse in the purification part of the process that much is evident. In this particular case a hot filtration hardly seemed worth it given the tiny amount of undissolved material, especially if not properly equipped to do one. The undissolved solid material maybe could have been removed some other way.





[Edited on 7-3-2015 by Hennig Brand]

Issues Associated with ETN Recrystallizations from Methanol

Performing the ETN synthesis described in the last few posts has caused me to remember a few things about problems associated with ETN recrystallizations from hot methanol and to search for explanations. The following is a U2U exchange with Philou where he gives a good explanation of what is likely happening at the higher recrystallization temperatures.

Quote:
Hello Philou,

I have noticed when recrystallizing ETN from methanol that the solution will turn a yellow-orange color and also that a lot of yield weight will be lost at the same time. This only seems to happen at temperatures approaching the melting point of ETN. For instance, if the methanol is only heated to 50C the solution seems to stay mostly clear and the final yield is greater. The yellow-orange material produced can be fairly easily washed from the precipitated ETN, but when not well washed it was noted that as the ETN was drying there was an acrid, irritating to the eyes and nose smell which came from the sample on close inspection.

I believe the ETN or lower nitrates are decomposing. Rosco suggested maybe transesterification when I mentioned it to him. Do you have an idea about what is happening?

Thanks,

Hennig


Hi HB,
Feel free to post this into your tread!
Yes Rosco is right transesterification seems plausible reason.
Usually it has to be catalysed by a base or an acid but owing to the "high heat" involved in your recrystalization process there are two concomittant process at work:

1°) Due to the heat, the equilibrium is set faster and some CH3-ONO2 is formed while trinitroerythritol (hydroxy in position one or two?) is formed; usually nitration or halogenation occurs faster at the external CH2OH what would tend to mean that the internal CHOH are more hydrolysable (or methanolisable) and would exchange faster their nitrate, so following me it is OH in position 2. Then the hydroxytrinitroerythritol is more water of methanol soluble and would disfavour correct crystallization of your ETN.

2°) The traces of CH3-ONO2 are hydrolysed or oxydised by the too high a heat yielding HNO3 and NxOy with CH2=O (formol-acrid smell), HCO2H (formic acid) and CO2 + H2O. Then acidic HNO3 and HCO2H will help further catalysis for transesterification. The NxOy will then oxydise some of the hydroxytrinitroerythritol into a ketonic variant more prompt to hydrolysis of the viccinal nitrate ester groups and thus accelarating the decay. End Quote


In the past if the recrystallization was done at the lower temperature, typical yields were normally about 1.4g of recrystallized product per gram of erythritol, whereas yields could go as low as 1g of recrystallized product per gram of erythritol if the recrystallization was done close to, or at, the boiling point of methanol. I would need to do more tests, but I remember from half a dozen or more smaller scale syntheses, done in the last few years, that even lowering the methanol solvent temperature to 50C would prevent all or nearly all of the yellow-orange color and yield loss. Lower solvent temperatures will mean that a certain amount more solvent will need to be used however.

The following picture shows the solution of 240g of crude ETN in methanol which had been carelessly let boil for 5-10 minutes.




[Edited on 13-3-2015 by Hennig Brand]

ETN: Recrystallized Yield & Melting Point Determination

Equilibrium moisture content was again reached and the recrystallized yield is better than I predicted. From the 150g of erythritol started with, 205g of recrystallized ETN with a melting point of ca. 60-61C was obtained, or about 1.37g of high purity ETN per gram of erythritol started with.

The plate on the left, in the attached image, holds the ETN which precipitated on cooling and plugged the filter when a hot filtration was attempted (dry weight 82g). The plate on the right holds the ETN which precipitated from the solution which passed the filter, some of which was precipitated by dilution of the methanol with water (dry weight 123g). I suspected that the purity would be low, but surprisingly both samples have basically the same melting point somewhere between 60 and 61C.

A little greater care could have been used to wash the yellow-orange impurity from the recrystallized product.

Despite the fairly decent results this time around, I have definitely noticed in the past that low yields and acrid smelling yellow-orange material production were associated with high solvent temperatures during recrystallization.




[Edited on 14-3-2015 by Hennig Brand]

Nitroglycerin - Fast and Effective Residual Acidity Neutralization Using Overhead Stirring

Quote: Originally posted by Hennig Brand

Very true, a preheated water bath would be much safer. Using a glass vessel directly on a hotplate is a little more convenient, but it really isn't worth the risk.

Quote: Originally posted by Tabun

Maybe it's a stupid question but what's the difference between a metal plate with x temperature and a bath with the same temperature?I mean...you can control the temperature with these things and I don't think you're going to turn it to...let's say 100 degrees Celsius to heat something to 50 degrees Celsius.

Water and metals have very different heat capacities.
The heat capacity is the amount of heat required to raise the temperature of an object or substance one degree. The temperature change is the difference between the final temperature ( T_f ) and the initial temperature ( T_i ).
Water's heat capacity is much higher than most metals, 4.179 Joules is required to bring the temperature of one gram of 0°C water up to 1°C. Iron's heat cap. is 0.450 J/g at 0°C. Thus water will heat up and cool down much slower than a hotplate of similar mass. There may be other reasons as well, but I'm a chemist, not a energetics/explosives synthesizer (not that you can't be both).

Quote: Originally posted by KesterDraconis

So I recently made nitroglycerin, as the next explosive on a long list to make (I hope to make the next TNT!). I did the hammer test on a brick with about half a milliliter (I made one and a half), and I learned to respect the substance even more when after my third strike (the first two broke the brick into three pieces and didn't detonate it, my third strike was with all my force) that little drop absorbed in a paper towel powdered a good bit of the brick piece underneath it and knocked out my hearing in one ear for a second (I wasn't wearing hearing protection, I thought it would sound like a loud firecracker...). Needless to say, I nearly pissed my pants. While I am amazed with its power, and have gained a new respect for it, I also want to make more of it. Yes I know contradiction right? I primarily want it though for the purpose of making dynamite. I am wondering, what material could I use where nitrocellulose or blackpowder deflagaration explosion would be sufficient to detonate it , or would something like that only work on pure nitroglycerin? (trying to stay away from more unstable primaries for the moment, though I will make them in the future, since I nearly have enough money to buy the equipment I want)

NG is easier to made than TNT. TNT is very complex.
NG is much more sensitive and a lot of hazards surround it.
I stopped playing with such things. I only use AN if I need to do something.
DON'T PLAY WITH YOUR LIFE COUNTER

Quote: Originally posted by ecos

Quote: Originally posted by KesterDraconis   So I recently made nitroglycerin, as the next explosive on a long list to make (I hope to make the next TNT!). I did the hammer test on a brick with about half a milliliter (I made one and a half), and I learned to respect the substance even more when after my third strike (the first two broke the brick into three pieces and didn't detonate it, my third strike was with all my force) that little drop absorbed in a paper towel powdered a good bit of the brick piece underneath it and knocked out my hearing in one ear for a second (I wasn't wearing hearing protection, I thought it would sound like a loud firecracker...). Needless to say, I nearly pissed my pants. While I am amazed with its power, and have gained a new respect for it, I also want to make more of it. Yes I know contradiction right? I primarily want it though for the purpose of making dynamite. I am wondering, what material could I use where nitrocellulose or blackpowder deflagaration explosion would be sufficient to detonate it , or would something like that only work on pure nitroglycerin? (trying to stay away from more unstable primaries for the moment, though I will make them in the future, since I nearly have enough money to buy the equipment I want) NG is easier to made than TNT. TNT is very complex. NG is much more sensitive and a lot of hazards surround it. I stopped playing with such things. I only use AN if I need to do something. DON'T PLAY WITH YOUR LIFE COUNTER

Quote: Originally posted by Hennig Brand

The better primaries are quite storage stable and have sensitivities low enough that they can be safely handled with proper technique. When you say gun powder and lead ball I assume you mean black powder and lead ball, if so it could probably work but might not be reliable. NG will gladly detonate at a lower detonation velocity if not initiated properly. I have never done it, but from what I have read even a .22LR can initiate dynamite at close range, but reliability is not great. Apparently anything much bigger and faster than a .22LR is quite reliable for initiating dynamite. The speed of the bullet has to be above the speed of sound to create a shockwave. However, even a lead ball traveling at 800fps could probably initiate pure NG, but I am not sure what the detonation velocity would be or if it would be consistent and reliable shot to shot.

Since if improperly initiated NG can have very low stable detonation velocities, and it is brisance which counts the most with initiators, it can be a very poor initiator even compared to mercury fulminate. Also, NG tends not to perform as well in the tiny charge sizes and diameters commonly employed with initiators.

The following was taken from "Military Explosives":

Mercury fulminate detonation velocity at 4.17g/cc is 5400m/s.






[Edited on 12-5-2015 by Hennig Brand]

I really don't like to play with NG. I synthesized it twice and had a hard headache but i might do it again in future for discovering shaped charges.

Anway, I didnt see any NG mixture with Al powder .
I think Al if added to AN or other mixtures it increases the power of detonation a lot.

any reason why we don't use Al powder added to NG , PETN ,... ?