Sciencemadness Discussion Board - RDX E method

RDX E method

krazypunk50 - 10-7-2010 at 20:09

In the process, one of the chemicals needed is boron trifluoride. Do I need the actual gas or something like boron trifluoride etherate? Also, can I still do the synthesis without this catalyst?

mnick12 - 10-7-2010 at 22:14

Care to provide a reference to what you are talking about? I know of the E method but I am not sure which article you are talking about. Boron trifluoride is a catalyst in the reaction. So you may be able to get away without using BF3 but your are likely to have more by-products, and a lower yield. Which isnt really good considering the yields for this reaction is usually under 65% anyway.

per.y.ohlin - 10-7-2010 at 22:25

"Addition of boron fluoride to the mixture promotes the initiation of the reaction and increases its safety"
"The conduct of the reaction in the presence of boron fluoride reduces the number of by-products formed"
[Chemistry and Technology of Explosives Vol. III, T. Urbański, 1967 - Pg.109] (Translation by Marian Jurecki)

I would expect boron trifluoride etherate to work for this reaction, because ether is not very reactive.

krazypunk50 - 11-7-2010 at 07:25

Okay so the synthesis calls for the addition of 4% boron trifluoride. If I were to use the etherate, how would I calculate the percentage of boron trifluoride etherate to add to the solution?

quicksilver - 11-7-2010 at 12:13

You would calculate based on molar weight of materials in the synthesis. It's .5% as related
to your acetic anhydride.*

Very standard stuff. This method is called E-method after Ebele. This method require no HNO3.
However the method requires a great deal of acetic anhydride.... For an acetic anhydride
technique the yield is not guaranteed at 80% so I don't think it's worth it. But that's my opinion.

First the acetic anhydride is warmed up to 60 C and 0.5 % of BF3 is
added. Then, AN and paraformaldehyde are added maintaining
the temperature by cooling. As all the reagents have been added, the mixture
is cooled to 20 C and the product is filtrated, washed in water etc.
Yield generally 63..65 %, in laboratory scale up to 80 % has been achieved.
The cost of the acetic anhydride is high enough to suggest that the K method is
a better move. The only thing cool about the E method is that you may be able to substitute Trioxane for
the paraformaldehyde.

*The amounts are as per 100% of total (so .5% is a half percent) of total molar weight of
materials used. In this case whatever weight acetic anhydride.
{Ebele method: The amounts of the reagents can be calculated according to the
reaction: 3 CH2O + 3 NH4NO3 + 6 (CH3CO)2O -> (CH2N-NO2)3 + 12 CH3COOH} or whatever.
If you're asking yourself, "do I have to use the BF3?"
I really am guessing that it's a plant procedure due to the above.

[Edited on 11-7-2010 by quicksilver]

krazypunk50 - 11-7-2010 at 13:16

The first time I tried the synthesis, I did not use BF3 because it was not listed in my synthesis. Because of this, a higher temperature of 70-90°C was needed. I have yet to find out my yield because my product is still drying. When I'm able to get BF3 etherate, I'll try the normal synthesis. Also, acetic anhydride isn't that expensive. I get mine for $10 a pint (473ml). What is the % yield for the KA process?

quicksilver - 12-7-2010 at 06:01

I have also seen it absent from the Ebele method:; when it was presented as a lab. TTBoMK it's (the addition of BF3) a plant-level agenda. The yield for the KA process is said to be consistently higher [than a base comparison of the nitration of hexamine or direct nitration of hexamine di-nitrate]. I don't have the material in front of me me but the issue with the Ebele method is that it maintains a RANGE from 65-80 whereas the KA process is said to be consistently higher perhaps close to 80 but does not have fluctuations based upon temp, addition speed, & re-crystallization, etc.

The nitration of amines is not a high yield synthesis as is the synthesis of nitric esters, etc. The key to making RDX a military-industrial standard is that it essentially is cheap when compared to PETN (as the two are comparable in strength & utility). The precursors for RDX can be brought down to ammonia and formalin; essentially inexpensive materials. Whereas the precursor for PETN demands a level of purity in it's use of pentaeuryritol (sp?) which places a burden on manufacturing. The purity level was said to comprise what was known in Germany as Pentaeuryritol-M (the PETN precursor standard). The cost was then hinged on the availability [of precursors] and utility of the synthesis. If acetic anhydride is available or reproducible, RDX becomes substantially less expensive, regardless of projected yield.

I'm fairy sure someone will pipe in with the KA projected yield. A comparison of mfg. techniques has been published often enough to make that available. If not, I'd think it would be in either the PATR or PEP journals.

[Edited on 12-7-2010 by quicksilver]

The WiZard is In - 12-7-2010 at 07:01

Quote: Originally posted by krazypunk50

In the process, one of the chemicals needed is boron trifluoride. Do I need the actual gas or something like boron trifluoride etherate? Also, can I still do the synthesis without this catalyst?

---------
This snip-it courtesy of Google.com/books from Organic Chemistry
of Explosives

http://tinyurl.com/2ft4kza

By da boron tri-- is used to make HMX check Google.com/patents.

krazypunk50 - 12-7-2010 at 19:38

I used 130ml AA, 52.5g NH4NO3, and 19g paraformaldehyde. My yield before recrystallization-13.4g. after-4.4. It was very weird because I had a lot of impurities that would not dissolve in the hot acetone no matter what. Also, the product after recrystallization deflagrated different than rdx that was made by nitrating hexamethylenetetramine dinitrate. The color, too, was a little bit off. It was a more clear type white and the other rdx was a chalk white. Was there something wrong with my synthesis?

quicksilver - 13-7-2010 at 05:49

To the best of my knowledge....no. I have had the same experience with re-crystallization both the E, K and direct nitration of hexamine. I believe that the false reading is actually moisture in the crystal lattice prior to clean-up.
Frankly it's a real low yield lab. A great many people here investigated how to churn it up to even a solid 80%. But yields in the 70's% were considered normal fare. If the materials were more expensive than it would pose a problem. One of the better labs I'd done was a direct nitration of hexamine di-nitrate which only got me about half of the nitrated weight.

EDIT:
One thing I remember is when I re-crystallized and the water was pulled from the materiel I would often get larger beautiful clear rhomboid crystals of approx 1-1.5mm. as long as you're getting some of those then you can bet it's moisture. The whole yield won't be sharp clear crystals but you'll get perhaps 20-40% larger clear materiel.

[Edited on 13-7-2010 by quicksilver]

krazypunk50 - 13-7-2010 at 07:26

I noticed the rhomboid crystals, too, when I was recrystallizing. I have one question about the deflagration difference though. Since hmx is less soluble in acetone, it precipitates out first. Does this concentrating of the amount of hmx in the in the product make the deflagration different? (rdx from the dinitrate method burns like a jet of fire and it's yellow. my rdx melts first and the burns like a jet)

RDX WW II

The WiZard is In - 13-7-2010 at 10:45

For those interested in the development of RDX manufacturing during WW II I
notable for the Ross-Scheissler and Bachmann process which combined features
of the old Woolwich and Ross-Scheissler process. The Bachmann process was
adopted. (RDX Type-B).

Donald H Avery
The Science of War : Canadian Scientists and Allied Military Technology During
the Second World War
University of Toronto Press 1998

The book comes up short on chemistry.

W. A. Noyes, Jr. Ed.
Science in World War II — Chemistry
Little Brown 1948

Does a little better with the chemistry.

“It had taken Canadian, American, and British scientists more than a year to
convince the military establishment to use the new explosive, though RDX was 40
percent more powerful than TNT. By July 1943 a Kingsport, Tennessee, plant was
manufacturing 170 tons of it per day. To prevent the enemy from learning about
the new explosive*, shipments of it were labeled as golf balls; also information
about RDX was not shared with the USSR.

* The first unexploded bomb that fell on the homeland ….. /djh/

Tom Shachtman
Laboratory Warriors : How Allied Science and Technology Tipped the Balance in
World War II
Perennial 2002

See also Avery.

djh
----
Ralph B Baldwin
The Deadly Fuze : Secret Weapon [proximity fuze] of World War II

The molded [ethyl acetate] fuze nose's shape would
have been a dead giveaway to any spy. To obfuscate, APL
ordered 500,000 "rectal spreaders."

quicksilver - 14-7-2010 at 05:21

Quote: Originally posted by krazypunk50

I noticed the rhomboid crystals, too, when I was recrystallizing. I have one question about the deflagration difference though. Since hmx is less soluble in acetone, it precipitates out first. Does this concentrating of the amount of hmx in the in the product make the deflagration different? (rdx from the dinitrate method burns like a jet of fire and it's yellow. my rdx melts first and the burns like a jet)

In general the HMX yield during direct nitration (which may be the highest HMX by product yield synthesis) is still only less than 10%. So realistically I don't think that would account for it.
I'm afraid that you have to understand that it's a low return synthesis. However since you DO have acetic anhydride, there are several more that you can try & perhaps get more CONSISTENT results.
The Wizard's idea of reading up on Bachmann (in general actually) is one of the best. Bachmann did some of the widest published work with RDX and certainly would have answers where I have only read & done some labs like most everyone else. Most likely it will be some esoteric thing that will give you the direction you need. :-)

From what I know; it's a low-yield lab and most people have to be satisfied with it. But who knows? I doubt that you'll get yields in the 90's as I can't recall any but that means nothing as I only read a certain percentage of what's available obviously. You may be lucky and stumble on something really wonderful. I certainly hope you do & share it with us. I was eventually satisfied with what I was getting from direct nitration of hexamine di-nitrate basically because it was a very predictable yield after I had worked the addition times, initial temp, quench / drown temps, etc.
There ARE a lot of variables in any of the labs. IF you think upon contemplation of your synthesis that you may have been remiss in some way: obviously try it again with those changes!

EDIT:
The burning issue is too variable to really know. That's because the way in which something is burned can have inconsistencies like the type of flame exposure, the temp of the initial flame, the quantity burned, & structure of the burned materiel upon application of flame. That's why melting point machines are used: to stop the variables from ruining the outcome. If you have concerns about yield, the only realistic thing to do is read more and do many MORE labs. Taking notes EACH time to record actions taken so as to standardize your actions. Notes taken are really the key to finding out what's taking place because you can then compare them to a standardized synthesis.

[Edited on 14-7-2010 by quicksilver]

The WiZard is In - 14-7-2010 at 06:54

Quote: Originally posted by krazypunk50

In the process, one of the chemicals needed is boron trifluoride. Do I need the actual gas or something like boron trifluoride etherate? Also, can I still do the synthesis without this catalyst?

[Edited on 14-7-2010 by The WiZard is In]

krazypunk50 - 15-7-2010 at 19:01

Okay if this synthesis is always going to be low yield, I won't bother with the E method. Have you tried the KA method? If so, then what are your experiences with it? Yields?

quicksilver - 16-7-2010 at 08:30

I never had significant access to acetic anhydride. But when I did I tried most every method I could find that employed it. I can only report that the KA method APPEARS to be more consistent in it's yield whereas the E method can vary. Mostly, when determining what to experiment with I looked at the plant production techniques and what they used. Generally, production facilities needed something that was predictable.
Can you find a RDX production technique for a yield in the 90% range? I don't believe so. But with proper equipment / facilities you may be able to get consistent results in the 80's.
The ideal thing would be to study the formula elements to determine yield percentage so that you can determine what you are expecting to see. Then when setting up for a "KA" lab, try to find if there are "built in variables" which you could alter to maintain consistency. A cheap hot plate that really doesn't keep decent temperature? Poor measuring devices? These things can throw anyone off so that even a well defined lab has good result one day and shit the next.

The WiZard is In - 16-7-2010 at 09:05

Quote: Originally posted by quicksilver

I never had significant access to acetic anhydride. But when I did I tried most every method I could find that employed it. I can only report that the KA method APPEARS to be more consistent in it's yield whereas the E method can vary. Mostly, when determining what to experiment with I looked at the plant production techniques and what they used. Generally, production facilities needed something that was predictable.

Can you find a RDX production technique for a yield in the 90% range? I don't believe so. But with proper equipment / facilities you may be able to get consistent results in the 80's.

Ullmann [5th ed] sez

Woolwich process (No acetic anhydride) The yield bases on
hexamine is 78-80%.

KA and Bachmann. The yield is ca. 80-85%; [Based on what?]
Nitrous fumes are not evolved.

The product contains ca. 8-15% HMX, depending on the reaction
conditions.

-----
Within hours of each other on the same winter afternoon in 1941-42, three
hot sulphuric acid melting point baths blew up at U of T[oronto], McGill and
a university in the United States, all of them working on the RDX [explosive]
program. The Toronto event only left a surprised graduate student with his
glasses cracked and minor burn spots, but one of the others put a student
temporally in the hospital. The very next day newspapers reported explosion
of a milk test device using sulphuric acid. A science buff in the labs
announced that what was taking place was The First Revolt of the Molecules,
with sulphuric acid leading the way. Would chlorine, or maybe caustic soda
be next? Fortunately the molecules clamed down and the revolt did not spread.

Donald H Avery
The Science of War : Canadian Scientists and Allied Military Technology
During the Second World War
U of Toronto Press. 1998.

quicksilver - 17-7-2010 at 05:00

That whole group of books looked very interesting. I wanted to read them but couldn't find then via Amazon. Are they available from current publishers?

The WiZard is In - 17-7-2010 at 06:08

Quote: Originally posted by quicksilver

That whole group of books looked very interesting. I wanted to read them but couldn't find then via Amazon. Are they available from current publishers?

If you do be refering to Noyes, Avery &c., all three can be
had at Abebooks.com. However, Noyes is $130. I have also
found it listed as — Chemistry a History of the Chemistry
Components of the National Defense Research Committee
1940-1946, Hardcover. @ Exlibris.com $149.

If you search long enough you may find it for less. I spent
years looking for a copy that I could afford of Tri-Nitro-Glycerin
as Applied in the Hoosac Tunnel Submarine Blasting, etc, etc, Etc
Nowbray, Geo M. 1872. Now reprinted or can be DL'd from
Google books.

I did buy a complete run (1882-1928) of the
Journal of the Society of Chemical Industry, from
Abebooks for a quite reasonable price.

The WiZard is In - 17-7-2010 at 07:00

Quote: Originally posted by quicksilver

That whole group of books looked very interesting. I wanted to read them but couldn't find then via Amazon. Are they available from current publishers?

I would note in passing —

From Google.com/books

America's munitions 1917-1918: Report of Benedict Crowell
1919. 592 pages. I may be less expensive to buy a used copy.
$27.50 or a reprint $37 plus shipping.

Robert M Yerkes
The New World of Science : Its development during the war.
1920. 443 pages.

Hard copy $22 and up.

quicksilver - 18-7-2010 at 05:11

I appreciate that. ...Seems you and I share similar reading habits! Of all the $ I have spent on hobby related issues, by far the most has been on books, journals, etc.

quicksilver - 21-7-2010 at 06:36

Some time back there was some discussion of alternative RDX synthesis:
http://www.sciencemadness.org/talk/viewthread.php?tid=4701
Some of the contributions had some powerfully unique value as did the sourcing of Trioxane for formaldehyde (note that Trioxane had been sold at $1 per pound on a US market for some time. Perhaps one of the lest expensive sources of formaldehyde I can think of) . Basically, in large scale plant-level cost cutting there are some very interesting answers to getting a worthy RDX yield, IF you really search. And yes, it's not an easy task because mostly they are production secrets. I tried & came up with some directions but there are some very sharp contributors here that found some serious alternatives.

A lot of these threads are 5 years old or older. But there is some very interesting material during that time as many folks had access to some wonderful facilities. I wish I had more to tell you but in reality I found the simplest methods to be the most consistent & in fact what is often used at plant level!
Even the Discovery Channel had an episode entitled "Acids" that had some VERY interesting material of RDX mfg!

[Edited on 21-7-2010 by quicksilver]

krazypunk50 - 22-7-2010 at 06:34

I saw that episode! I believe they used hexamine with "strong" nitric acid and some other additives. At the end where they had the product being scooped up, I was extremely jealous. Was that just the direct nitration of hexamine?

quicksilver - 22-7-2010 at 06:48

Quote: Originally posted by krazypunk50

I saw that episode! I believe they used hexamine with "strong" nitric acid and some other additives. At the end where they had the product being scooped up, I was extremely jealous. Was that just the direct nitration of hexamine?

Indeed it was; albeit it was most likely the direct nitrate of hexamine di-nitrate - they choose a very simple route. Studying plant-level techniques will give you some ideas on both how to save money and how to maintain consistency. Predictability allows for the integration of safety and continual savings. I've used plant-level techniques with very productive results. It's often a need to adjust for batch size but that's a minor point; they have a lot to offer.

I'm guessing here but I believe that a direct nitration plant illustrates the simple cost factor of the acid. Breaking down hexamine to components; the formaldehyde is inexpensive in bulk - the issue was the price of the acid.
For hobby chemists, if a quality distillation glass is available the same agenda applies.

AndersHoveland - 21-9-2011 at 17:11

It is quite likely that BF3 is not absolutely required.

"Dimethylamine has been prepared in 65% yield by the dehydration of dimethylamine nitrate in acetic anhydride to which 4% mole percentage anhydrous zinc chloride had been added. The same reaction in the absence of the [zinc chloride] generates only a 5% yield of dimethyl nitramine."

dimethyl nitramine has the structure (CH3)2N-NO2, which can also be written CH3N(NO2)CH3.

dimethylamine nitrate has the structure (CH3)2NH2[+] NO3[-]

It seems likely that anhydrous ZnCl2 could be used instead of BF3, which is much more hazardous, difficult to prepare, and obscure. In either case, both BF3 and ZnCl2 are Lewis acids, which act as catalysts.

I am not sure that anhydrous ZnCl2 can be prepared simply by heating the hydrate. It might decompose, giving off HCl and leaving behind ZnO.

One way that the anhydrous form may be prepared is to pass anhydrous HCl gas into ethyl ether, containing zinc metal. Interestingly, the ZnCl2 that forms is soluble in ether, perhaps because an adduct is formed or because the Zn-Cl bonds have a more covalent character, suggested by the compounds low melting point of 292°C.

It was also suggested on this forum that polyphophoric acid could possibly be used instead of the acetic anhydride, and I would be inclined to agree with this idea.

[Edited on 22-9-2011 by AndersHoveland]

AndersHoveland - 21-9-2011 at 22:13

The so called "E" method of nitration, initially developed by Ebele, does not require any nitric acid, but does require a large excess of acetic anhydride. Later, in 1940, independant from the research of the german Ebele, Ross and Schiessler, at McGill University, obtained RDX from formaldehyde, ammonium nitrate and acetic anhydride in the absence of nitric acid.
"Addition of boron fluoride to the mixture promotes the initiation of the reaction and increases its safety"
"The conduct of the reaction in the presence of boron fluoride reduces the number of by-products formed"
[Chemistry and Technology of Explosives Vol. III, T. Urbański, 1967 - Pg.109]

AndersHoveland - 7-1-2012 at 02:37

I had a thought that reacting trioxane, ammonium nitrate, and anhydrous AlCl3, in ethyl ether/DMSO solvent, might form RDX.

This would essentially be no different than the conventional E method, except that AlCl3 would act as the dehydrating agent and Lewis acid catalyst instead of the acetic anhydride and BF3.

Another thread discussing preparation of AlCl3,
http://www.sciencemadness.org/talk/viewthread.php?tid=18394

quicksilver - 7-1-2012 at 06:15

I never had any success with trioxane for a hexamine substitute (in this context). It's a shame as wasting acetic anhydride is almost sinful and of course I attempted direct nitration. Frankly there is some material written about this in a "search" on trioxane. Good ammonia source, but won't cut it for RDX.

Motherload - 28-8-2012 at 20:17

Can Paraformaldehyde be subsituted with Trioxane ?
I dont believe the the subsitution of Hexamine with Trioxane is implied.
I also do not see how Trioxane can be a source of ammonia.
Formaldehyde X3=Trioxane
Formaldehyde Xn=Paraformaldehyde
NH4NO3 + AeAn (90*C) + Trioxane (Instead of Paraformaldehyde)

[Edited on 29-8-2012 by Motherload]