the home of online investigations

“A Naive Set of Assumptions” – An Expert’s View on Ted Postol Hexamine Theories

August 6, 2018

By Cheryl Rofer

Translations: Русский

In the wake of the August 2013 Ghouta chemical attack, Ted Postol attacked Dan Kaszeta’s argument that hexamine, C6H12N4, was a marker for Sarin made by the Syrian government. Postol is a professor emeritus of Science, Technology, and International Security at the Massachusetts Institute of Technology; Kaszeta is a consultant with experience in chemical warfare issues and worked for the United States Secret Service, the folks who guard the President.

Amines are a part of Sarin production. When Sarin is manufactured, HF is produced. That HF will corrode equipment and destroy the Sarin, so something is needed to neutralize it. HF is an acid and amines (hexamine and others) are bases, which tie up (or scavenge) the HF and neutralize its damaging properties.

We now know that hexamine is the Syrian government’s amine of choice for Sarin manufacture. Postol got that wrong because of two misunderstandings, one in elementary chemistry and the other in basic chemical technology. They are accompanied by smaller errors. The sum of the errors gives the impression of someone with no knowledge of chemistry being aided by a person who has taken Chemistry 101. Postol published his and Kaszeta’s emails on the subject, but has not compiled his argument into an internet post or journal article.

Amines are nitrogen compounds derived from ammonia, NH3. The three hydrogens point to the corners of a tetrahedron. The fourth corner is filled by an electron pair. In amines, carbon-containing groups replace one or more of the hydrogens, but the electron pair remains.

That electron pair can bind to acids. The positively charged hydrogen in HF, which is also called a proton, attaches to the electron pair. That leaves a negatively charged fluorine, which sticks around to form a salt. Many drugs are ammonium salts.

Postol gets hung up on a question of solubility. Carefully planned experiments for first-year chemistry students carry out acid-base neutralizations in solution. This is an excellent pedagogical practice, particularly with the aid of color-changing indicators, but it is not the only way this chemistry can be done.

Postol tries to work out the chemical engineering of Sarin synthesis from what he believes are first principles, but a great deal of chemical engineering depends on empirical findings and workarounds. He believes that Sarin must be produced pure, with no solvent. But the reaction produces significant heat, which a solvent must remove. Thus, he takes the stoichiometry of a solvent-reactant mixture that is used in Sarin preparation as the stoichiometry of the reaction. [Stoichiometry is another word for the ratios of reactants and products in a chemical reaction.] A military manual lists the mixture of isopropanol, a reactant, and isopropamine, an acid scavenger, as “OPA.”

Postol finds the ratio of the numbers of moles of isopropanol of moles of isopropamine to be 2.5, which he concludes is the number of HF molecules one isopropamine molecule will soak up.

But the structure of the isopropamine molecule tells us how many HF molecules it can scavenge. Isopropamine, C3H9N, has only one nitrogen with one electron pair and thus can scavenge only one HF molecule. Postol badgers Kaszeta for a “scientific reference” that gives the number of HF molecules hexamine can scavenge. Hexamine has four amine nitrogens, so the answer is four. No reference is needed. A more advanced view notes that the molecular configuration somewhat hides the electron pairs, so four would be the maximum number. The actual number might be less.

That’s the first-year chemistry mistake. Now for the elementary chemical technology mistake.

It starts with another concept taught in first-year chemistry. Every chemical reaction has a quantitative equilibrium at a given temperature and pressure. The product of the concentrations of the reactants divided by the concentration of the product is a constant. For the chemical reaction

the equilibrium constant is represented by

Where the brackets indicate concentrations. More accurately, one might consider what is called chemical activity, but concentrations are a reasonable approximation for activity.

Adding an excess of one of the reactants pushes the reaction toward maximum product yield. In the case of the last step in the Sarin synthesis, the two reactants are methylphosphonyl difluoride and isopropanol. The reactant used to push the equilibrium would be the cheaper and easier to procure, in this case, isopropanol, also known as rubbing alcohol. It can also be used as the solvent. Postol assumes that no solvent is used, because it would have to be removed from the product Sarin. But chemical engineers know many ways to remove solvents, and it’s possible that in a binary shell the solvent would aid dispersal.

Additionally, Postol’s concern about the solubility of hexamine is misplaced for reasons of chemical technology. Agitation can be used to mix a powdered solid with a liquid to achieve a desired reaction. Chemical engineers have many ways to make difficult reactions work.

There are a number of smaller mistakes in Postol’s argument. He misunderstands the difference between alcohols and ketones in his comment about hydrogenation of acetone on page 4; fluorine and its derivatives are misspelled in his figures; he misunderstands what a hydrogen bond is on page 9 and ignores its function in solubility; on page 10, he switches from weight percent to volume percent without introducing a density.

Postol is operating from a naive set of assumptions, based on limited experience in a first-year chemistry laboratory, presumably the experience of his informant. The result is a wrong-headed approach to the problem and nonsensical demands of Kaszeta. Nothing in Postol’s argument sounds like it was written by a chemist or someone with a working knowledge of chemistry.

Cheryl Rofer

Cheryl Rofer writes scientific and political commentary. She was a chemist at the Los Alamos National Laboratory for 35 years. She regularly provides background information to reporters for major publications and has been quoted in the New York Times, Washington Post, and Vox. Her work at Los Alamos included projects in fossil fuels, laser development, chemical weapons, open-source intelligence techniques, and the nuclear fuel cycle. She has published in scientific and political science journals and edited a book. She holds an A.B. from Ripon College and an M.S. from the University of California at Berkeley.

Join the Bellingcat Mailing List:

Enter your email address to receive a weekly digest of Bellingcat posts, links to open source research articles, and more.

Support Bellingcat

You can support the work of Bellingcat by donating through the below link:

40 Comments

  1. Nobby Chock

    From the article…

    “Amines are a part of Sarin production. When Sarin is manufactured, HF is produced. That HF will corrode equipment and destroy the Sarin, so something is needed to neutralize it. HF is an acid and amines (hexamine and others) are bases, which tie up (or scavenge) the HF and neutralize its damaging properties.

    Amines are nitrogen compounds derived from ammonia, NH3. The three hydrogens point to the corners of a tetrahedron. The fourth corner is filled by an electron pair. In amines, carbon-containing groups replace one or more of the hydrogens, but the electron pair remains.

    That electron pair can bind to acids. The positively charged hydrogen in HF, which is also called a proton, attaches to the electron pair. That leaves a negatively charged fluorine, which sticks around to form a salt. Many drugs are ammonium salts.”

    So what salt would be produced when hexamine scavenges HF?…..and was any of this salt found? Since hexamine supposedly has other battlefield uses, what specifically enables hexamine to be used as a marker for sarin?

    Reply
    • Cheryl Rofer

      The salt produced is heaxaminium fluoride, C6H12N4HF. Yes it was. I’ve linked a discussion at “We now know” that answers your last question.

      Reply
      • Concerned Citizen

        Cheryl Rofer – August 6, 2018 wrote:
        “The salt produced is heaxaminium fluoride, C6H12N4HF. Yes it was. ”

        I hadn’t heard the OPCW had reported finding any hexamine salts. Do you have a link to an official document to confirm this?

        Reply
      • Concerned Citizen

        Are you sure C6H12N4HF exists?

        There are only 2 references on the entire internet to C6H12N4HF, one of which is you on this web page.

        Reply
        • Nobby Chock

          I would also be interested in seeing a reference to the OPCW discovery of “Hexaminium Fluoride”…

          Reply
        • DDTea

          Are you insinuating that this compound does not exist because it is poorly described in the literature?

          Hexamine (a.k.a. urotropine) seems to be well-known for scrubbing HF and forming hexamine-HF adducts.

          See:

          Ennan, A. A.; Brazovskaya, O. M.; Chopotarev, A. N. Products of the reaction between hydrogen fluoride and hexamethylenetetramine. Zhurnal Obshchei Khimii, 1975, Vol. 45, Issue 3, p. 706.

          Ennan, A. A.; Chobotarev, A. N.; Brazovskaya, O. M. “Hydrofluoric acid-​hexamethylenetetramine-​water system,” Zhurnal Neorganicheskoi Khimii, 1975, Vol 20, Issue 3, pp. 786-790

          Ennan, A. A.; Lapshin, V. A.; Brazovskaya, O. M.; Grishuk, N. S.; Mikhailovina, S. K. “Corrosion of steels in aqueous solutions of hydrogen fluoride containing urotropine,” Izvestiya Vysshikh Uchebnykh Zavedenii, Khimiya i Khimicheskaya Tekhnologiya, 1975, Vol.18, Issue 5, p. 840.

          Ennan, A. A.; Brazovskaya, O. M.; Kosheleva, N. N.; Mikhailovina, S. K. “Removing hydrogen fluoride from gases” USSR patent SU 801860, 1981.

          Reply
          • Concerned Citizen

            It’s not that it’s poorly described, it doesn’t exist at all in any literature.

          • DDTea

            Yes it does. I just cited references that describe complexes of HF and hexamine.

          • Concerned Citizen

            DDTea – August 8, 2018
            Yes it does.

            No it doesn’t. You can’t cite anything that mentions C6H12N4HF. The only place that mentions it is this post on Bcat.

            Conclusion – The existence of C6H12N4HF is dubious to say the least.

          • oui oui

            you said that “There are only 2 references on the entire internet to C6H12N4HF, one of which is you on this web page.”
            now there is only Bellingcat , but what is this other reference
            google C6H12N4HF and you find elibrary.ru
            conclusion : you are not

    • DDTea

      Can you elaborate on “other battlefield uses,” particularly in the context of it being found in a grenade full of sarin?

      Moreover, if hexamine is so ubiquitous that it dusts entire battlefields, then it would have been found in control samples mentioned in OPCW reports. Instead, it always found together with Sarin decomposition products.

      Reply
    • Cheryl Rofer

      I gave one reply. No more for random pseudonyms who clearly don’t know much chemistry.

      Reply
      • Concerned Citizen

        Again, does C6H12N4HF actually exist, and how does this formula you’ve written make any sense given that above you claim hexamine can scavenge 4 flourine atoms?

        How come there’s only 1 F not 4 F’s?

        Reply
        • Nobby Chock

          Cheryl has already condescended to give one reply….apparently that should be enough for random pseudonyms who don’t know much chemistry…

          Reply
        • DDTea

          It doesn’t matter whether it’s 1, 2, 3, or 4. It depends entirely on the stoichiometry, and the various salts can interconvert. It still serves the purpose of mopping up HF. The question you are asking is totally irrelevant, and just shows how deep your ignorance of the topic is.

          Reply
          • Concerned Citizen

            Alternatively, Cheryl has just made up an imaginary chemical C6H12N4HF and both you and Cheryl are talking nonsense.

            In the absence of any actual scientific sources to refer to, it’s hard to say which is true.

          • DDTea

            No, it’s not hard to know. You are willfully ignorant.

            This is simple acid-base chemistry. The pKa’s of hexamine and HF are well-known. These are empirical thermodynamic parameters of acidity. HF is 4.89. Hexaminium is 3.17.

            This gives an equilibrium constant for hexaminium-HF formation of 10^(4.89-3.17)= 52.5 = Keq.

            Acid-base reactions are extremely fast.

            Thermodynamics and Kinetics are in agreement with me and Cheryl. Nothing but cheap disinformation is on yours.

            If you’re not talking science, you have nothing more to say.

          • DDTea

            *HF is 3.17. Hexaminium is 4.89.

            Equilibrium favors formation of weaker acid.

          • Concerned Citizen

            Find me a source outside Bellingcat that mentions the existence of C6H12N4HF, and I might start believing you.

            Until then, sorry, but no.

          • DDTea

            You need to work on your library skills. This is some of what Scifinder turned up.

            Salts containing 1, 2, 3, and 4 equivalents of HF each have Chemical Abstract Service numbers–a unique number assigned to chemicals described in the open literature. Plainly, Hexamine-Hydrofluoride salts have all been prepared and described.

            Hexamine – 1 HF : CAS#31011-93-5
            Hexamine – 2 HF: CAS#24911-57-7
            Hexamine – 3 HF: CAS#56339-87-8
            Hexamine – 4 HF: CAS#55593-43-6
            Hexamine – x HF: CAS#69036-63-1 (x = 1 – 4 )

            Some references where their preparation and properties are described (there are others):

            1. Ennan, A. A.; Brazovskaya, O. M.; Chopotarev, A. N. Products of the reaction between hydrogen fluoride and hexamethylenetetramine. Zhurnal Obshchei Khimii, 1975, Vol. 45, Issue 3, p. 706.

            Abstract: The reaction of C6H12N4 with HF gave 1:1, 1:2, 1:3, and 1:4 cryst. adducts having cubic, orthorhombic, monoclinic and plate-​like crystal forms, resp. The individuality of the compds. is confirmed by the x-​ray diffraction.

            2. Ennan, A. A.; Anikeev, V. A.; Berezina, L. P.; Chobotarev, A. N.; Firsov, A. G. Composition and some properties of hexamethylenetetramine hydrofluorides. Zhurnal Neorganicheskoi Khimii, Volume 15, Issue 10, Pages 2857-9, 1970

            Abstract: Reaction of hexamethylenete-​tramine(I) with HF gives 1:1 and 1:2 adducts. Conductometric study proved formation of 1:1 species but its sepn. failed. Clear cryst. I.2HF sepd. after a mixt. contg. a 1:2 equiv. of reagents was kept for few days above H2SO4. The ir spectra of I and I.2HF are given. Regeneration of free I from I.2HF was studied using NaF, KF, NH4F, Al(OH)​3, NaHCO3 and NaAlO2. Only the last 2 reagents gave a good sepn. of products.

            Obscure works, to be sure. You’ll have to go into a brick and mortar university chemistry library to read them. Call them up, see if it’s in their catalog, and see if you can visit.

            Believe whatever you want though. Just don’t expect anyone else to do the same.

  2. Mad Dog

    Thank you Cheryl. I can’t wait for the St. Petersburg minions to attack your credibility and knowledge, just as they hit back at Dan. Funny, though sad at the same time as these folks tend to overlook the abject horror Assad has foisted up his own citizens. Nice piece of work!

    Reply
    • Black Star

      Looks like they were only able to answer with “deny everything just because”. Very weak, but natural, since random trolls usually do not know much about chemistry.

      Reply
  3. Dan

    Sorta confused by your Keq. Usually the products divided by the reactants. Unless you we’re talking about the reverse equilibrium?

    Reply
    • Cheryl Rofer

      Ah, sorry about that. I should have consulted a first-year chemistry textbook. I’ve used it so many times in both directions over the years. It doesn’t matter either way. Still a constant or its reciprocal, and still operates in the way I described.

      Reply
  4. Nobby Chock

    Cheryl Rofer – August 6, 2018 writes

    “Postol badgers Kaszeta for a “scientific reference” that gives the number of HF molecules hexamine can scavenge. Hexamine has four amine nitrogens, so the answer is four. No reference is needed. A more advanced view notes that the molecular configuration somewhat hides the electron pairs, so four would be the maximum number. The actual number might be less.”

    In fact Postol is expressing the “advanced view” regarding scavenging capability of hexamine….check page 7 of the Postol pdf you linked…Postol is already hypothesising 4 as a theoretical maximum and is asking Kaszeta for referenced clarification….

    Reply
    • DDTea

      His asking for a “referenced clarification” was nonetheless silly. His logical train was to determine whether or not a stoichiometric amount of hexamine would be soluble in isopropanol.

      But regardless of whether it is soluble or insoluble in IPA, we don’t know anything about its solubility in IPA/DF mixture. But more fundamentally, solubility is irrelevant. As Cheryl Rofer mentioned, heterogeneous reactions are totally viable. In fact, they’re commonplace.

      Yet Postol did not know this, and could not grasp this, because his ignorance is rivalled only by his arrogance.

      Reply
  5. Maxy

    Just curious: Does the author know more about the results of the OPCW investigation than B cat‘s CW expert?

    Cheryl R. “The salt produced is hexaminium fluoride, C6H12N4HF. Yes it was found.“

    Dan K. “There’s no mention of any HF‐Hexamine salts …… in the field results.“ (post.-debunks-kasz.pdf, p. 11, K.‘s email dated Friday, June 13, 2014 2:30 PM – link in the article)

    Cheryl, could you enlighten us? They found hexaminium fluoride in Ghouta, really? Sounds interesting.

    Reply
  6. Cheryl Rofer

    If you pseudonymous folks can find someone who knows some chemistry, I’ll be glad to respond to their comments. Meanwhile, thanks to DDTea, who does know some chemistry.

    Reply
    • Concerned Citizen

      It wasn’t really a chemistry question.

      It was a question about facts. You claim the OPCW found hexamine salts. The trouble is both bellingcat’s own ‘expert’ and the OPCW itself say they didn’t.

      Could you clarify this please.

      Reply
      • Black Star

        But you yourself do not care about facts, since you are only trying to find loopholes to continue your denial.

        Reply
    • Maxy

      “No! I won‘t tell you!“ “Come on, it might be really important and could change …..“ “No! I won‘t tell you!“ “Please, you might be the only one who ….“ “No! I won‘t tell you! No!“

      Forgive me, sure looks like you are (were) a good chemist, but I can‘t help it: your personal behaviour (after YOU had made this astonishing claim!) doesn‘t make you look very good, to put it mildly.

      So let‘s forget this kindergarten episode.

      Reply
  7. Adrian Kent

    And again Bellingcat bangs on about Hexamine. The fact is though, that there is very little evidence of a mass release of sarin (or even a sarin like substance) in any of the alleged attacks. All the ‘evidence’ so far presented (either in the form of samples or testimonies) has been provided by opposition groups.

    When finally the OPCW get to examine the scene of one of these alleged attacks and take the samples themselves, using the protocols that they previously stated were essential for reliable analysis, they find that these testimonies were false. A reasonable approach would be to re-evaluate the previous findings in this context.

    A group / website not completely dedicated to supporting the company-line would certainly undertake this re-evaulation. It speaks volumes that you have not.

    Reply
    • Black Star

      “All the ‘evidence’ so far presented (either in the form of samples or testimonies) has been provided by opposition groups. ”

      You really think the perpetrators would present evidence of their crime?

      Reply
      • Nobby Chock

        “You really think the perpetrators would present evidence of their crime?”

        Do you really think “opposition groups” are likely to impart unbiased testimony?

        Reply
  8. Concerned Citizen

    DDTea – August 8, 2018
    You need to work on your library skills. This is some of what Scifinder turned up.

    Where’s the links?

    Reply

Leave a Reply

  • (will not be published)