Sciencemadness Discussion Board

Introduction to "Novichok" Agents

DDTea - 16-3-2004 at 13:57

While doing some research on the internet concerning Novichok agents, I came across an unusually informative review on Amazon.com for the Handbook of Chemical and Biological Warfare Agents. Being rather impressed by the liberal use of references and detailed information, including some formulas, I took it upon myself to edit the review (rephrased some things; basically put it in better English, since it was written by a Russian) and took the time to draw the formulas in MS Paint. I will not bother linking to the review itself, but will instead include my "improved" version, in MS Word form. It serves as a useful introduction to the "Novichok" series of Nerve Agents, and includes useful references (I suspect most are written in Russian..). I don't know if this is any new information to you, but it was new to me :)

Attachment: Novichoks, Dusty Agents, GV and GP agents.doc (38kB)
This file has been downloaded 6750 times


DDTea - 17-3-2004 at 12:04

Just from looking at the structure of these agents, my guess to precursors are Phosphorus Oxychloride, Phosgene Oxime, some Fluorinating agent, and maybe Ethylene Chlorohydrin (looking at the second Novichok structure). The only other question is how to get the third group attached to the central Phosphorus-- the C-CC-X .

My guess is the synthesis would look something like this...I'm just throwing out ideas now to get discussion :)

HON=C(Cl2) + F --> HON=C(Cl)F + Cl

O=PCl3 + HON=C(Cl)F --> O=PCl2(-ON=C(Cl)F ) + HCl

O=PCl2(-ON=C(Cl)F) + HO-C2-Cl --> O=PCl(-ON=C(Cl)F)(-O-C2-Cl) + HCl

I'm thinking along the lines of the simple Tabun synthesis using Phosphorus Oxychloride, where the various groups are simply attached as shown above, with HCl or NaCl being the usual side-products. Following this logic, this could perhaps be a "simple" Novichok agent whose synthesis should not be much more complex than any G-Agent's:

O=P(-O-CC-Cl)(-O-N=C(Cl)(F))F

Another aspect of Novichoks worth noting are the unsaturated and halogenated side-chains. Perhaps this could explain their special toxicity, because they allow for multiple leaving-groups. However, I don't believe the Dihaloformaldoxime group is an active group--but rather a "stabilizing" group (I just made that term up, but it gets the point across).

One thing that is often brought up about treatment of Nerve Agent poisoning with Oximes-- the threat of forming highly toxic Phosphorylated Oximes. So to me, it looks like the Novichok agents play on this, but at the same time prevent Oxime treatment (as there is already an Oxime group attached).

What I am wondering is why two different halogens are used on the Dihaloformaldoxime group. Do you think that they are trying to take advantage of the difference in reactivities of the halogens, whereas if there is a F along side the Cl, the Cl may more readily react?

DDTea - 17-3-2004 at 19:33

Well, i've found some data related to toxicity-- just estimates and assumptions and some, you will seem, are a bit off.

Quote:


"Novichok 5 estimated to exceed effectiveness of VX by 5 to 8 times. Novichok 7 estimated to exceed effectiveness of soman by 10 times.
"

"Very rapid [action]"

"[symptoms] Assumed to be similar to the effects of other nerve agents listed above "

"Assumed to be similar to treatment methods for other nerve agents listed above"



The part that i can safely say is false is the treatment... Oxime treatments do not work against Novichok poisoning. As for Atropine, I don't know.

I'm assuming the structures listed by the Amazon.com reviewer are Novichoks 5 and 7... simply because information on Novichok is so limited. As such, I am assuming he used the structures of the Novichoks most well known-- and so did
http://www.stimson.org/cbw/?sn=CB2001121893#5. where I found the above information.

fritz - 20-3-2004 at 15:43

Oh, nice!
This is intresting! The first time I got something special like a formula about novichok agents!
I did so many searches about novitchok agents already but my results were not very promising. some years ago I had an intresting report about secret russian CW-agents researchs but unfortunatelly I lost it!
So I´ll try to resume my search results about and will post it here ASAP!

vulture - 21-3-2004 at 12:56

Hasn't there been somekind of incident with a lab where these agents were being researched?

DDTea - 23-3-2004 at 19:45

It wouldn't surprise me with the numbers of accidents the USSR has had-- Chernobyl, that Anthrax release, etc. I haven't heard of a nerve agent release, however...but if it did occur, the Russians would most likely cover it up. They were very secretive about their military, and they still are; and this makes it all the more difficult to get meaningful information about Novichok agents.

I am wondering, however: are there any Russian-speaking members on this forum, who would not mind doing a bit of translating of some of the books mentioned in the above Word file? Or, maybe give a list of useful words in Russian related to Novichok research...i.e.: the Cyrillic spelling for Novichok itself ( i believe it would be pronounced 'No-wee-shock';), to at least allow us to do Google Searches? From there, we can easily Babelfish any Russian results.

fritz - 26-3-2004 at 15:33

O.k. this is the result of my researches on novichok/foliant. I also looked up some of the informations given in Samosa´s paper.
You may regard this as a first output of information being far from complete. I I will get more intresting informations on this subjects I will publish it here. And, yes Vulture there was an accident with this substances it is mentioned in one of the resources I used (I listed them in my word document)

Attachment: INFORMATION.doc (61kB)
This file has been downloaded 7791 times


DDTea - 26-3-2004 at 19:48

I guess that is what we call good research :) . I am wondering--were most of your sources in English, or were much of them in German or Russian? I am having a hard time finding much in English, but if you feel like using it, the Russian word for "Novichok" is " Hoвичoк ," courtesy of my Russian friend :). It is a rather common word, meaning "Rookie" or "New-Guy" , so you may get a lot of junk results. I guess I'll have to ask for some "qualifying" words from her next time I see her.

Now, on to the information. The big area of interest here seems to be about Phosphorylated Alkanoyl Chloride Oximes, from Zhurnal Obshchei Khimii. The Trialkyl Phosphate should be relatively easy to prepare, as it is seen in the syntheses of many nerve agents:

PCl3 + ROH --(CCl4)--> P(OR3) + RCl + HCl

As for the second reactant, X-C(R1)2-NO2, What if the two R1 groups were substituted with Cl and F, respectively? Alternately, if they were ALL substituted with Cl, then it becomes a very familiar compound--Chloropicrin. The question then is whether or not this would react in the same way.

If so, then the reaction to produce a very dangerous Nerve Agent looks to be unbelievably simple:

PCl3 + ROH --(CCl4)--> P(OR)3

P(OR)3 + CCl3NO2 --(CCl4)--> PO4R2(N=CCl2)

The product would then be distilled out.

[Edited on 3-27-04 by Samosa]

fritz - 27-3-2004 at 02:16

All of my sources were in english. And I was able to read the russian journal because there is an english form ;). unfortunatelly I´m not able to read russian so i also will have no use for russian information.
To your reaction-suggestions: Yes this synthesis looks very easy! The most complicated step seems to me the synthesis of Cl2FCNO2 or ClFC=NO. The reaction with chloropicrin is mentioned in the J.A.C.S.-article. But it doesn´t seem to be a good way to the novichok-compounds because the reaction is said to be very violent at -40°C :o producing smoke and flames!

PainKilla - 29-4-2004 at 04:37

MY first post at this forum heh. I speak russian so I shall look into this if people want. Samosa/his friend is right on the meaning of Novichok. I'll try doing a search on some search engines (russian) and see if I can get any information...

fritz - 1-5-2004 at 01:12

Oh, that´s nice and may be very useful!;)
May I ask if you have already some informations about this class of chemicals?I have to admit that I´m a bit confused by the informations I have. It is said that the manufacture of these compounds should be very easy. But the chemistry-journals I looked up couldn´t confirm this! In fact the synthesis looks very difficult and uses some very strange compounds (e.g. Cl2FCNO2)

PainKilla - 3-5-2004 at 04:16

Well as you are I am sort of lost :/. Looking through various forums and articles I have gotten mixed results ranging from synthesis from simple and readily avalible substances like fertilizers and other things:o. But I have also read that it requires special equipment and it's not something as easy as that. Most sites however list them as being made from fertilizers (hence the secrecy since it's easy to hide production if it's made so simply) Some sites say soldiers carry the 2nd product with them and add alcohol. :( Not good for soldiers heh... I am still trying to see if the scientist who revealed this added any information through the years (Vil Mirzayanov)

DDTea - 16-5-2004 at 19:09

Looking at more Amazon.com reviews, I came across our old friend Anatoly Kuntsevich...

Quote:
More details would be fine, November 16, 2003
Reviewer: Anatoly Kuntsevich from Moscow, Russia
Although this book does not reveal the precise chemical formulas for the Novichok class of nerve agents it introduces into the hidden world of russian chem-bio weapon designers. The intelligence still fears to make public that Novichoks belong to organophosporus compounds containing the double halogenated oxime like -O-N=C(F)Cl group and that beside P.P.Kirpichev also I.V.Martnov and Yu.A.Kruglak from GosNIOKhT developed the principle of these extremely toxic OP oximes during the mid 60's already (and published also) which resist reactivation by other oximes. These chemicals an be made by heating only of substituted 1,3,2-dioxaphospholanes indicated slighly in this book . Hopefully int'l organizations will make public more details for the protection of other citizens than just army soldiers soon.


My understanding of the nomenclature of OPs isn't so great, so could someone explain what 1,3,2-dioxapospholanes would look like? :)

Do a quick google search on Anatoly Kuntsevich... He is quite an interesting character. He is a former General and is the head of the Committee for Problems of the Chemical and Biological Weapons Convention. Beyond that, he was Boris Yeltsin's personal adviser on Chemical Weapons and was later assigned to abolishing Russia's Chemical and Biological Weapons program. I'm sure there is much to be learned from him; maybe if we could find an e-mail address or something (since he seems to frequen Amazon.com...), we could find something neat :)

souran - 17-5-2004 at 00:22

I'm sorry, I'm russian and I will speak russian.
Дело в том, что отзыв, написаный Кунцевичем недоставерен. Анатолий Кунцевич умер в 2002 г. Что касается Новичков, то очень сомнительно, чтобы ацетонитрил мог участвовать в синтезе фосфорилированных оксимов. Если интересно, пишите.

souran - 17-5-2004 at 00:46

1,2,3-Диоксофосфоланы, это пятичленное кольцо, в котором атомы кислорода находятся в положении 1,3. Фосор в положении 2. Нуклеофильнок езамещение в ацетонитриле идет по атому углерода. Образуется вероятно иминоэфир. Если исходный ОР-compound содержит связь Р-Cl, то реакция идет по атому N. Образуется имидофосфорильное соединение.

FritzHaber - 17-5-2004 at 04:48

Quote:
Originally posted by souran
1,2,3-Диоксофосфоланы, это пятичленное кольцо, в котором атомы кислорода находятся в положении 1,3. Фосор в положении 2. Нуклеофильнок езамещение в ацетонитриле идет по атому углерода. Образуется вероятно иминоэфир. Если исходный ОР-compound содержит связь Р-Cl, то реакция идет по атому N. Образуется имидофосфорильное соединение.
gee...my russian isn't perfect, but as far as my poor cyrilic reaches, I can see, this one says like 1,2,3-dioxophospholanes are...
"heterocyclopentane (five-membered ring) derivatives, namelly those, having C1 and C3 substitued by an O atome, the C2 beeing substitued by a P(3+) atome, ...O-P(X)-O..
X is a (pseudo)halogene."
these are the cyclic phosphonic compounds, reacting with flurodichloronitrosomethane to yield Novichoks.

DDTea - 17-5-2004 at 07:28

As it turns out, fritz (not to be confused with FritzHaber) had this information in the little word file he uploaded... I suggest downloading it if you have not already--it mentions quite a few useful reactions. By the way, this forum has some rules about speaking in English, if I recall correctly... If you don't speak it well, I suggest using http://babelfish.altavista.com/ -- they have a Russian to English translator :).

[Edited on 5-17-04 by Samosa]

Polverone - 17-5-2004 at 11:05

Rules about writing in English? I don't recall any such rules. The only problem is that most of the membership here will no longer understand you if you do not write in English, since our membership is so widely scattered.

souran - 20-5-2004 at 01:59

I’m sorry for my awful English, but it's my first latter in foreign language.
It’s known, that one of the precursors OF Novichok agents is acetonitrile. How it may react with OP-precursors? Common pesticide precursors contain P-SH, P-OH, P-Hal bonds.
For instance: COP(=O)(OC)S; COP(=O)(OC)Cl
I suggest that in the first case imidoilphosphate created, in the second: alkilidenamydophoshate created.

Additionaly, Anatoly Kuntsevich died in 2002. The review is written in 2003. This review can contain false information. Most likely that someone wrote this review under pseudonym Anatoly Kuntsevich. I distrust that exactly syntheses of Novichok compounds are described in journal articles. Most likely that these are related compounds. All articles of journal dated 1967-1972. Supertoxic compound, “Substance А-230” created between 1985 and 1991. The “Substance А-230” tested in only unitary form. For binary weapon a “Substance А-232”, similar to “Substance А-230” was created. Exactly in synthesis of “Substance A-232” and (maybe) “Substance A-234” acetonitrile may be used. I certain, that US military have already created Novichok compounds and described their properties. It may be useful to search RTECS database for Novichoks and related compounds.

fritz - 22-5-2004 at 00:51

whoops I must have competely overlooked this intresting converstion!
First of all i want to tell you I am preparing a new, revised information-paper about the novichok-stuff. Unfortunatelly I have too much other work to do so you have to wait a few days (I hope not weeks!)

I agree with souran, if Mr Kutsevich was a former general I doubt he would publicate informations about classified weapons under his own name (especially if he is dead since two years ;))
So I also think that care should be taken with his informations. All I read about the class of substances he described stands in opposite to the other informations I have from more or less official sources. But it may also be he HAS in fact some true informations and uses the pseudonym Kuntsevich as some kind of tip to his knowledge.
I have read about MeCN as a precursor but also I have no clue about how this may fit in a organophosphoros structure. Alcohols are mentioned too for the binary compounds but I guess these may react similiar as in the binary GB/VX mixtures.
I consider the suggestion of searching the RTECS-database about these compounds as a good idea! Lets look what could be found there!

FritzHaber - 22-5-2004 at 03:03

well...presuming, that acetonitrile is a precursor, not solvent, I had this idea last night:

(R-)(X<sub>1</sub>-)P=O(-X<sub>2</sub>;) + H<sub>3</sub>C-CN ---> (R-)(X<sub>1</sub>-)P=O(-N=C[-X<sub>2</sub>]-CH<sub>3</sub>;),
where X1 = fluorine, cyanide, alkoxy, etc. radical, and X2 = chlorine, bromine, amino etc. radical, the bond P-X1 beeing more stable than that P-X2 or even P-N=C(X2)-CH3.
this would yield certainly interresting AChE-inhibitors...
further, I would consider this type of organophosphates to be much likely potent CW agents:
1)
(R,R'N-CH<sub>2</sub>-CH<sub>2</sub>-)(F-)P=O(-N=C(F)-CF<sub>3</sub>;)
2)
(R,R'N-CH<sub>2</sub>-CH<sub>2</sub>-)(F-)P=O(-O-N=C(F)-CF<sub>3</sub>;)

anyway, someone should contact some russian military chemist and buy the detailled formula for some $1.000 ;)

fritz - 22-5-2004 at 12:57

Yes this may be a great idea! But if all the secrets are revealed we will loose an intresting topic to discuss about. How boring! Hm, but on the other hand...

Nice first name Mr. Haber! ;) And of course a very intresting person you got this pseudonym off!
I thought of a similiar way for the use of MeCN before I got the original literature. I thought of using it for creating the oxime function suggested in samosa´s paper. But I came to no solution of the problem because I don´t know how to get the oxygen between N and P.

souran - 27-5-2004 at 18:44

Quote:
Originally posted by FritzHaber
well...presuming, that acetonitrile is a precursor, not solvent, I had this idea last night:

(R-)(X<sub>1</sub>-)P=O(-X<sub>2</sub>;) + H<sub>3</sub>C-CN ---> (R-)(X<sub>1</sub>-)P=O(-N=C[-X<sub>2</sub>]-CH<sub>3</sub>;),
where X1 = fluorine, cyanide, alkoxy, etc. radical, and X2 = chlorine, bromine, amino etc. radical, the bond P-X1 beeing more stable than that P-X2 or even P-N=C(X2)-CH3.
this would yield certainly interresting AChE-inhibitors...
further, I would consider this type of organophosphates to be much likely potent CW agents:
1)
(R,R'N-CH<sub>2</sub>-CH<sub>2</sub>-)(F-)P=O(-N=C(F)-CF<sub>3</sub>;)
2)
(R,R'N-CH<sub>2</sub>-CH<sub>2</sub>-)(F-)P=O(-O-N=C(F)-CF<sub>3</sub>;)

anyway, someone should contact some russian military chemist and buy the detailled formula for some $1.000 ;)


To buy a state secret for 1000$ is daring idea. I am afraid to disillusion you but corrupt military chemists are so greedy for the most part. 1000$ is not quite sufficient. Moreover, I suppose the secret is sold already.:)
I mostly agree with Mr. FritzHaber, but if X2 = -OH, SH, amino I guess the reaction would look like this:

(CH3O)2P=O(SH) + MeCN --> (CH3O)2P=O(-S-C(CH3)=NH)

If X2 = Hal reaction would look like:

(CH3O)2P=O(Hal) + MeCN --> (CH3O)2P=O(-N=C(CH3)(Hal))

The product of first reaction is related to compound (CH3O)2P=O(-S-C(CH(CH3)2)=NH-CH3) which is highly toxic (http://wcb.ucr.edu/wcb/schools/CNAS/entm/tmiller/1/modules/p...)

Here are more examples of highly toxic related compounds(in ChemSketch smiles):

COP(=O)(OC)\N=C1/SC(CO1)C
CCOP(=O)(OCC)\N=C1/SCCS1 (Phospholane)
Clc1ccc(cc1)OP(=O)(Oc2ccc(cc2)Cl)\N=C\C (Phosacetim)

It is known two-step reaction of cholinesterase reactivation:

1. (R1-)(R2-)P=O(OR) + R3-CH=N-OH --> (R1-)(R2-)P=O(-O-N=CH-R3) + R-OH
2. (R1-)(R2-)P=O(-O-N=CH-R3) --> (R1-)(R2-)P=O(-OH) + R3-CN

May MeCN react with P-OH containing compounds?

[Edited on 28-5-2004 by souran]

souran - 24-6-2004 at 23:23

Is anybody here in this topic?

-------------------------------------------

Do NOT DEMAND answers please. People may or may not reply to your reply, usually it takes some time. The forum is not a chatbox.

[Edited on 25-6-2004 by vulture]

Reverend Necroticus Rex - 7-9-2004 at 17:20

I just searched on novichok agents, came up with this:

http://66.102.11.104/search?q=cache:v9FPKVzfKaAJ:www.cisworldservices.org/publications/CSM_FALL2002.pdf+novichok+agents&hl=en

Refers to "aconitrile", most likely, given the tone of the previous messages to be acetonitrile, mixed with the ubiquitous "common pesticide" in what is hinted to be something like a one-step procedure.

Could lead to a one pot synthesis of one of the nocichok agents maybe:D


Edit: found this, could someone maybe link to the references if they have access to the full article?

http://taylorandfrancis.metapress.com/app/home/contribution....

[Edited on 8-9-2004 by Reverend Necroticus Rex]

sparkgap - 5-9-2005 at 06:54

A bit off topic, but... oh well...

http://cns.miis.edu/pubs/npr/vol07/72/72bozh.pdf

sparky (~_~)

hinz - 5-9-2005 at 12:33

I think someone made a mistake Fritz or Samosa. When I looked once again through the attachments of Fritz and Samosa, I noticed that the compound CAS-RN 26102-97-6
When all the same atoms are counted together it’s C3H4Cl2F2NO3P
Which would be


Cl-CH2-CH2-O-PO(F)-O-N=C(F)(Cl)


But in Samosa’s drawing it’s C3Cl2F2NO3P, which would be


Cl-C≡C-O-PO(F)-O-N=C(F)(Cl)


I think Samosa forgot the hydrogen atoms, or is it really an unsaturated 1-chloracetylene group ?
The same thing is at the novichok CAS RN 26102-99-8 (C5H8Cl2F2NO3P at Fritz and C5Cl2F2NO3P at Samosa)

Maybe all organophosphate structures are wrong or does anyone know what fluorohydroxy group is (maybe P-O-F) ? (CAS-RN 26102-97-6 is
[[(2-chloroethoxy)fluorohydroxyphosphinyl]oxy]carbonimidic chloride fluoride )

And doesn’t … phosphin…stand for an trivalent phosphorous compound, the pentavalent compound would be …phosphon…

All the stuff is so strange and unfortunately secret, but I wan’t to know it, maybe someone could try to synthesize an easy organophospate (methyl or ethyl ) wit a double halogenated formaldoxime group. Maybe Ethyl dichlorformaldoxime fluorophosphate and test their toxicity. At the time I am working on a small furnace to produce some phosphorous and if I should have success I will try to syntesize some of the stuff here after I made some easy organophosphates.




[Edited on 6-9-2005 by hinz]

Chris The Great - 5-9-2005 at 13:46

Don't try it without a negative pressure glove box, or you might not ever get to post your results.....

I remember that you are correct in the structures. I think Megalomania over at E&W looked up the CAS numbers and found that the structures do not have the alkyne bond, and that the original auther was not clear in indicating the hydrogens or something.

Also, consider that dihalogenated formoximes are incredibly nasty substances on their own. Skin contact causes extreme pain and very slow healing wounds, the vapours cause blindness, etc. This assumes one merely mixes the formoxime with the phosphorus halide to get the wanted structure, there are other less direct (and extremely dangerous from what I understand) routes with chloropicrin, involving flames and explosions from the energy released.

As for the naming, I think that it is just a really bad name, and it has the 'oxy' group listed right after. I think that the name represents the structure but in a bad way. Or I'm misinterpreting the name... naming phosphorous compounds is quite strange In my opinion.

sparkgap - 7-9-2005 at 01:36

The reason organophosphorus nomenclature is confusing is that the first few workers on this subject didn't exactly have the same set of standards. For instance, one uses "phosphorothioate", while another uses "thiophosphate", and some go so far as to distinguish "phosphorothiolate" (>P-S) and "phosphorothionate" (>P=S).

Another source of confusion is that some workers tend to use a mix of the CAS and |IUPAC systems. :o

Here go some links on organophosphorus nomenclature:

http://www.acdlabs.com/iupac/nomenclature/93/r93_507.htm

http://www.chem.qmul.ac.uk/iupac/misc/phospho.html

sparky (~_~)

Conor579 - 6-8-2015 at 11:53

Wouldn't it be possible to replace certain chemicals in the Tabun synthesis pathway to make a variety nerve agent? I'm just asking since I've been looking at the synthesis and I've been thinking "Substitute the initial amine compound w/ another amine other than dimethylamine and then just use another salt having a halogen (sodium fluoride) and another organic oxide group (like methanol instead of ethanol) producing a whole new nerve agent plus an acid completely independent of cyanide" Is it possible to do it like that? Or no?

careysub - 6-8-2015 at 16:04

This is exactly what Schrader et al were doing in the 1930s and 1940s to produce the thousands of candidate agents that were screened at the time. The agents you know about were the most successful ones.

There others that were almost as good, and which have been investigated by other weapon programs, like Iraq's.

You don't want to mess with this stuff unless you are doing microchemistry AND really, really know what you are doing.

It is a good thing that chemical weapons have fallen out of favor with advanced nations. With modern computational design technologies significantly more effective agents are no doubt possible.

Conor579 - 6-8-2015 at 20:14

But how successful WERE the current nerve agents we know about? What others had they tested? I like to ask questions xD

softbeard - 7-8-2015 at 08:45

Quote: Originally posted by Conor579  
But how successful WERE the current nerve agents we know about? What others had they tested? I like to ask questions xD


Nothing wrong with asking questions. The answer is that current nerve agents we know about are extremely "successful" at producing lethality in mammals, including humans.
Just about every conceivable variation of (OR)2P=O-X (prototypically, X=F) type organo-phosphate compounds has been studied for non-reversible acetylcholine-esterase inhibitor activity. Some, like VX 'nerve gas', have been found to be extremely potent and environmentally persistant.
Even some of the simplest organo-phosphate compounds of this type, like di-isopropyl phosphorofluoridate are quite toxic. The LC 50 for 10 min exposure of di-isopropyl phosphorofluoridate was 0.36 mg/l for rats and 0.44 mg/l for mice. This makes the compound more toxic than cyanogen chloride (1); on par, more or less, with HCN . And it's not even considered a 'real' nerve gas.

There really is not very much interesting chemically about these compounds, aside from from them being able to be made very selective in their toxicity. So that potent insecticides can be made which have quite low toxicity in mammals (ie., Malathion). In general, these are not a fun group of chemicals to play with.


1. "Some Aspects Of The Chemistry of Organic Compounds Containing P and F", B. Saunders, A. Todd, 1957, Cambridge Press

careysub - 7-8-2015 at 10:00

Quote: Originally posted by softbeard  
Quote: Originally posted by Conor579  
But how successful WERE the current nerve agents we know about? What others had they tested? I like to ask questions xD


Nothing wrong with asking questions. The answer is that current nerve agents we know about are extremely "successful" at producing lethality in mammals, including humans.
Just about every conceivable variation of (OR)2P=O-X (prototypically, X=F) type organo-phosphate compounds has been studied for non-reversible acetylcholine-esterase inhibitor activity. Some, like VX 'nerve gas', have been found to be extremely potent and environmentally persistant.
Even some of the simplest organo-phosphate compounds of this type, like di-isopropyl phosphorofluoridate are quite toxic. The LC 50 for 10 min exposure of di-isopropyl phosphorofluoridate was 0.36 mg/l for rats and 0.44 mg/l for mice. This makes the compound more toxic than cyanogen chloride (1); on par, more or less, with HCN . And it's not even considered a 'real' nerve gas.

There really is not very much interesting chemically about these compounds, aside from from them being able to be made very selective in their toxicity. So that potent insecticides can be made which have quite low toxicity in mammals (ie., Malathion). In general, these are not a fun group of chemicals to play with.


1. "Some Aspects Of The Chemistry of Organic Compounds Containing P and F", B. Saunders, A. Todd, 1957, Cambridge Press


The chemistry/biochemistry and history of these compounds can be quite interesting - and as pesticides have useful non military applications.

To qualify as a "good" nerve gas a compound has to have a favorable combination of physical, chemical, and biochemical characteristics: storage stability, volatility, resistance to hydrolysis, absorption, potency, and ease of manufacture.

Diisopropyl phosphorofluoridate (aka DFP or isoflurophate) was good enough to actually be stockpiled by the U.S. in WWII as a war gas (codename PF3), even though (as noted above) it is "only" as toxic as HCN.

A primary reason for standardizing this agent is that it causes extreme miosis (contraction of the pupil) at exposures far below the lethal level, which severely impairs vision giving it useful harrassing value. It is also a cumulative poison and persistent as well (unlike HCN). The miotic effect sees this chemical used in optometry today.

The common assertion found in the historical literature that the Allies did not know about nerve gases is wrong, they just did not know the superior ones found by Germany. Germany explored several thousand agents, the Allies just several hundred. The U.S. program worked with the direct predecessor of tabun, but did not try cyanidation (which makes tabun) among the substituents they tested.

Of the three G-agents well known after WWII tabun was the least toxic (5 times the maximum toxicity of HCN) but was sufficiently low volatility and good hydrolysis resistance to make it a persistent agent.

Sarin was 20 times as toxic as HCN and highly volatile (about the same as water). This was the standard agent adopted by the US.

Soman (O-Pinacolyl methylphosphonofluoridate) is about 30 times as toxic as HCN, persistent, and had a property making it one of most harmful nerve gases - it crosses the blood-brain barrier and breaks down slowly causing long-term CNS poisoning in survivors. It was however very expensive to manufacture due to the difficulty of making pinacolyl alcohol for which no good production processes existed at the time. After WWII Soviet chemists developed a good industrial process and this became one of their principal agents.

Cyclosarin (GF, cyclohexyl methylphosphonofluoridate) is somewhat similar to soman in being persistent (and is even more toxic). It was produced by Iraq, but the higher cost of manufacture kept it out of the US arsenal - which used the even more toxic V-agents for its persistent agents.

Many other related compounds are very toxic, without being super toxic, may be nonvolatile (making exposure difficult to arrange), may break down too easily, may not be stable in storage, may be expensive to make, etc. etc.

[Edited on 7-8-2015 by careysub]