Sciencemadness Discussion Board

Trimethyl Phosphate

Corrosive Joeseph - 16-2-2020 at 07:18

Is it feasible to think that methanol can be esterified with phosphoric acid to form Me3PO4..... Hopefully peeps can chime in, I am off down the rabbit hole of research and will post my findings.


/CJ

clearly_not_atara - 16-2-2020 at 07:49

Short answer: no.

Long answer: nooooooooooooooooooooooooooooooooo.

Phosphoric acid is the worst. It tends to form polymers rather than clean dehydration products. So for example the reaction of methanol and metaphosphoric acid will produce products like MeH3P2O7. Distilling any amount of Me3PO4 out of this is a fool's errand.

It might be possible to transesterify dimethyl carbonate with phosphoric acid. But even here I would expect a nasty polymeric mess.

Corrosive Joeseph - 16-2-2020 at 08:35

Balls..... Probably best to buy it..... Thanks clearly_not.


This is the best source of information I can find so far on OTC trimethyl phosphate preparation.
'trimethyl phosphate' - Hive Chemistry Discourse sub-forum
https://tinyurl.com/rvnao8j

Attaching references.


/CJ


Attachment: REAXYS - Trimethyl phosphate (150 Reactions).pdf (682kB)
This file has been downloaded 989 times

Metacelsus - 16-2-2020 at 09:43

If you have POCl3, you can react that with methanol. P2O5 might also work.

Corrosive Joeseph - 16-2-2020 at 15:03

Yeah, they surely will.

Unfortunately I am looking for a more OTC route than either of those..... If somebody can get those reagents, they can surely get trimethyl phospate.
It's not that I can't get it, but I would really like to find a way that is accessible to everybody.


/CJ

rockyit98 - 16-2-2020 at 15:51

excess anhy. MeOH with P4O10 will give what you want.

clearly_not_atara - 17-2-2020 at 08:37

CJ: If you want an OTC methylating agent, dimethyl oxalate is more likely to be practical. Or DMC in PC, PC from PG + urea.

The downside is that we don't know a whole lot about dimethyl oxalate -- nobody seems to have used it! It's been discussed since forever, of course. But when we actually pull out the flasks everyone uses something else. So we don't know if DMOx can methylate salicylaldehyde, for example.

Likewise, we think DMC in PC can methylate salicylaldehyde (a useful test case for "difficult nucleophile") thanks to bp elevation and SN2 promotion by PC. But again, we're not sure.

Basically we have two pretty good ideas and we're not sure if either of them works.

[Edited on 17-2-2020 by clearly_not_atara]

Corrosive Joeseph - 17-2-2020 at 08:53

First off, I must apologize for being stubborn....... What do you think of this one....?

"Trimethyl phosphate is prepared by the reaction of silver phosphate and methyl iodide"


Weger; Justus Liebigs Annalen der Chemie; vol. 221; (1883); p. 89
https://onlinelibrary.wiley.com/doi/10.1002/jlac.18832210106

Rabzewitsch-Subkowski; Journal fuer Praktische Chemie (Leipzig); vol. <2>86; (1912); p. 319
https://onlinelibrary.wiley.com/doi/10.1002/prac.19120860128

Rabzewitsch-Subkowski; Zhurnal Russkago Fiziko-Khimicheskago Obshchestva; vol. 44; (1912); p. 152;

My Sci-hub is down or I would or I would post the papers...... Anybody read German.......?


/CJ

clearly_not_atara - 17-2-2020 at 09:05

Without reading it, I'd guess that that will work. Nucleophile exchange in silver "salts" (esters) with iodides can be used to make almost anything. For example, methylene ditosylate is made similarly by rxn of TsOAg with CH2I2. Methylene diacetate from AgOAc with CH2Cl2 is a much better route to Ac2O than salt pyrolysis.

But there is a long and mostly disappointing history of Ag-facilitated reactions in amateur chemistry. They usually work well, but they never catch on. Silver compounds are expensive, while metallic silver is difficult to work with (requires HNO3 or MeSO3H).

Furthermore the whole point of this methylation odyssey was to avoid using methyl iodide in the fist place.

[Edited on 17-2-2020 by clearly_not_atara]

Corrosive Joeseph - 17-2-2020 at 10:07

Hmmm, your points are duly noted...... Also, your input is much appreciated.

Translation of the two articles just in -

The first one, by Felix Weger
Quote:


Trimethyl phosphate was received from Prof Lossen and that it was prepared using phosphorous silver and methyl iodide. No further details are given.



What a dissapointment that was..... The second one from J. Rabcewicz‐Lubkowsky is a little better -


Quote:


The ester was obtained by heating methyl iodide and phosphorous silver in an autoclave at 100 °C. The ester distilled at 196-197°C"




More later....


/CJ

clearly_not_atara - 17-2-2020 at 10:47

I should add that if this procedure works for silver phosphite (Ag2HPO3), the product phosphonates can be halogenated to dialkyl halophosphate esters, which can be very interesting.

Corrosive Joeseph - 17-2-2020 at 17:18

Quote: Originally posted by clearly_not_atara  
I should add that if this procedure works for silver phosphite (Ag2HPO3)


Excuse me, what.....? You lost me a little with that post. The reference which led me to those papers stated that "phosphorous silver" was actually silver orthophosphate.

https://en.wikipedia.org/wiki/Silver_phosphate


/CJ

clearly_not_atara - 17-2-2020 at 20:37

Sorry, relatively few people know about H-phosphonic acid (or simply phosphonic acid) and most people call it "phosphorous acid":

http://en.wikipedia.org/wiki/Phosphorous_acid

It is a weak diprotic acid with one hydrogen atom bonded to phosphorus. By the usual considerations it should be easier to alkylate phosphonate than phosphate because it is less symmetric and the atoms less electronegative.

Esters of phosphonic acid have formulas HP(OR)2O. I was wondering if you might be able to brominate these to the BrP(OR)2O, which is a strong dehydrating agent.

Corrosive Joeseph - 17-2-2020 at 22:53

Hmmm, I wish I knew more...... I want to go back over the esterification but first, I found this analogous reaction..... How well will this preform if n-butyl bromide is substituted with methyl iodide........?
Quote:


Silver phosphate (26.5 g., 0.062 mols) and 50 g (0.36 moles) n-butyl bromide were refluxed for 2 hours in a flask containing a magnetic stirring device. The mixture is allowed to stand at room temperature over night and the next day the mixture is refluxed again for 6 hours. During this time, an odor associated with butylene was evident. The mixture in the flask was extracted with 3 portions of hot petroleum ether (30 ml each). The combined petroleum ether extracts were washed first with an equal volume of 0.1N HCl, then with an equal volume of 0.1N NaOH, then two equal volume portions of water and dried over anhydrous sodium sulfate. After removal of the lower boiling constituents at the water pump there was obtained 9.8 g (59% yield) of tributyl phosphate boiling between 174° C at 28 mm and 180° C at 29 mm.



The preparation of tri-n-butyl phosphate by W. H Baldwin and C. E. Higgins (Oak Ridge National Laboratory 1951)

https://www.prepchem.com/synthesis-of-tributyl-phosphate/


/CJ

clearly_not_atara - 18-2-2020 at 05:31

I think you're going to want a solvent for that reaction. Boiling points:

nBuBr: 102 C
MeI: 42 C

The reaction temperature will be 60 C lower if performed neat. Seems like a disadvantage. Consider DMSO, PC, etc.

Corrosive Joeseph - 18-2-2020 at 18:12

Okay, let's put that to the side for a minute....... We have one contender at least.
Quote: Originally posted by Corrosive Joeseph  
I wish I knew more...... I want to go back over the esterification



"In a typical example of our process, 150 g. of commercial diethyl phosphate containing about 65% diethyl phosphate was partially neutralized with 26 g. of 50% NaOH solution and the mixture placed in a distilling flask and heated under vacuum (17-25 mm.) until distillation was substantially complete. The distillate coming over up to 150 C., consisting largely of water and a. small amount of alcohol, was discarded.

Pyrolysis started at 177° C. with a gradual thickening of the charge. As the pyrolysis and distillation proceeded the charge became a slurry and finally baked to a white solid and the temperature increased up to about 3000 C. without any evidence of destructive decomposition. The distilled product was a clear colorless liquid weighing 89 g., and represented a yield of 75% triethyl phosphate -having a boiling range of 100-105° C. at 16 mm. pressure."

http://www.freepatentsonline.com/2410118.html


/CJ


Attachment: US 2410118 - Method of Producing Trialkyl Phosphate Esters (1944).pdf (543kB)
This file has been downloaded 454 times

monolithic - 18-2-2020 at 18:26

Quote: Originally posted by Corrosive Joeseph  
Okay, let's put that to the side for a minute....... We have one contender at least.

Quote: Originally posted by Corrosive Joeseph  
I wish I knew more...... I want to go back over the esterification



"In a typical example of our process, 150 g. of commercial diethyl phosphate containing about 65% diethyl phosphate was partially neutralized with 26 g. of 50% NaOH solution and the mixture placed in a distilling flask and heated under vacuum (17-25 mm.) until distillation was substantially complete. The distillate coming over up to 150 C., consisting largely of water and a. small amount of alcohol, was discarded.

Pyrolysis started at 177° C. with a gradual thickening of the charge. As the pyrolysis and distillation proceeded the charge became a slurry and finally baked to a white solid and the temperature increased up to about 3000 C. without any evidence of destructive decomposition. The distilled product was a clear colorless liquid weighing 89 g., and represented a yield of 75% triethyl phosphate -having a boiling range of 100-105° C. at 16 mm. pressure."

http://www.freepatentsonline.com/2410118.html


/CJ


Isn't dimethyl phosphate ester extremely expensive? I think your other post looks much more promising. Silver phosphate can be synthesized from silver nitrate (OTC) and phosphoric acid (OTC.) Methyl iodide is also OTC, from phosphoric acid and iodide salts. :)

[Edited on 2-19-2020 by monolithic]

Corrosive Joeseph - 18-2-2020 at 19:39

Thank you, I thought it was quite the find!

Hang on, it says "di-ethyl"...... I would be hoping it is possible to mono or di alkylate phosphoric acid before using that process above. Read the patent, there are a number of similar procedures contained within it.

Yes, it looks like these two posted procedures are possibly the only ones available to regular Joe's. And corrosive Joe's too. :)

I can buy trimethyl phosphate but that's not the point of this thread.... I would prefer that anybody who wants it can make it from simple ingredients.


/CJ

Corrosive Joeseph - 18-2-2020 at 21:03

Taken from -

Alkyl Esters of Phosphoric Acid - Hochwalt et al. (1942)
Industrial & Engineering Chemistry, 34(1), 20–25.
https://sci-hub.tw/10.1021/ie50385a005
Quote:

The pure monoalkyl and dialkyl esters have been prepared and described [Ref. 13]



[Ref 13] -

Ueber die gegenseitige Einwirkung der Phosphorsäure und des Alkohols (About the Interaction of Phosphoric Acid and Alcohol)
Pelouuze (1833).
Annalen Der Pharmacie, 6(2), 129–146.
https://sci-hub.tw/10.1002/jlac.18330060202


Back later with translation...


/CJ

Prepic - 19-2-2020 at 07:06

Just a thought from my side...

Since phosphoric acid can form pyrophosphoric acid, triphosphoric acid and higher polymer chains such in polyphosphoric acid, would it be reasonable to think polyphosphoric acid could react with alcohols in general to from mono/dialkyl phosphates?

According to wikipedia, polyphospates hydrolyse in water and higher temperatures along with acidic conditions speed up the hydrolysis. Perhaps this can may be useful/required for a reaction with alcohols?

clearly_not_atara - 19-2-2020 at 08:43

Prepic: The reaction of metaphosphoric acid, the most dehydrated phase obtained at "reasonable" temperatures, with an alcohol generates only the monoester:

ROH + HPO3 >> (HO)2(RO)PO

So diesters cannot be obtained from polyphosphoric acids without additional dehydration.

CJ: links to PDF files on sci-hub are unstable, so it's better to upload the file or just link the abstract.

If I had to guess, the German paper prepares diesters by the rxn:

2 P2O5 + 4 ROH >> 2 (RO)2PO2H + 2 HPO3

Prepic - 19-2-2020 at 10:18

From the attached patent [1] I got from the discussion at the Hive Chemistry Discourse sub-forum 'trimethyl phosphate' ( https://tinyurl.com/rvnao8j )

The patent mentions the following line:
"Attempts to pyrolyze commercial monoalkyl phosphates with and without added alkali were not in general practicable. For example, no trialkyl esters were formed without added alkali, but where sufficient caustic soda was added to give a theoretical monosodium phosphate distillation residue, the pyrolysis yield of trialkyl ester was increased to 31.5% in the case of the methyl ester."

This means trimethylphosphate can be made from monomethylphosphate and the methylphosphate obtained by reacting a metaphosphate salt with methanol.

I feel like im missing something...

___________________________

[1] A.P. 2410118 (1944) Victor Chemical Works Methods for producing trialkyl phosphate esters

Attachment: TMP-US2410118A.pdf (235kB)
This file has been downloaded 430 times

Corrosive Joeseph - 20-2-2020 at 22:18

Quote: Originally posted by Prepic  

I feel like im missing something...


Well, you are not the only one.
Quote: Originally posted by clearly_not_atara  

CJ: links to PDF files on sci-hub are unstable, so it's better to upload the file or just link the abstract.


'Alkyl Esters of Phosphoric Acid - Hochwalt et al. (1942)' is 9.96MBs and too large for upload.
'Pelouze - About the Interaction of Phosphoric Acid and Alcohol (1883)' is now attached.


A German friend was kind enough to have a look and informs me of the following...
Quote:


In the 1833 paper you send me the author is continously talking about salts he made and characterized.

I have to admit that I'm not sure what this paper is about. 90% of the time the author is talking about a salt of phosphoric acid and barium. Not once the word ester occurs.

"100 g of 96% alcohol and 100 g phosphoric acid of a thick, sirupy consistency were mixed and hold at 60-80 °C for a couple minutes and diluted with 7 to 8 times volume of water and saturated the mixture with a as fine as possible tritruated BaCO3 in water. The mixture is now heated to remove an excess of water, then let cool to 70 °C and filtered. During cooling 'phoshprous tartarous baryte' precipitate as beautiful, white hexagon leaves. From this salt all other 'phosphorous tartarous' salts and 'phosphorous tartarous acid' can be made."

Maybe you can ask someone else who knows chemistry what they mean with 'phosphorous tartarous acid' (Phosphorweinsäure) because this part makes no sense for me. There is no tartaric acid involved. Maybe it's an old term I don't know about?"




Have we any more Germans here, can somebody else have a look......?


/CJ


Attachment: Pelouze - About the Interaction of Phosphoric Acid and Alcohol (1883).pdf (681kB)
This file has been downloaded 438 times

dawt - 9-4-2020 at 00:22

Quote:

Maybe you can ask someone else who knows chemistry what they mean with 'phosphorous tartarous acid' (Phosphorweinsäure) because this part makes no sense for me. There is no tartaric acid involved. Maybe it's an old term I don't know about?


In this case the correct translation would be phosphovinic acid. It's an old term for ethylphosphoric acid (probably a mixture of mono- and diester), same as sulfovinic acid is a synonym for ethyl sulfate.

stoichiometric_steve - 12-4-2020 at 14:04

Quote: Originally posted by Corrosive Joeseph  

can somebody else have a look......?


phosphorous tartarous acid = "Barium Ethylphosphate", presumably Ba2+ Et-OPO32-, if that can even exist.

S.C. Wack - 12-4-2020 at 18:29

In 1864 the formula was supposed to be Ba2C2H5PO4. Not sure how that goes.
https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1863...

clearly_not_atara - 13-4-2020 at 08:44

S.C.Wack: it seems like they replace "Ba2" with "Ag2" on the next page. Therefore I would consider that the "Ba2" means something like "barium donates two moles of electrons" in a modern reading. Otherwise the formula is very weird.

clearly_not_atara - 12-5-2020 at 19:37

I had another idea. Consider tetramethylammonium phosphate:
(Me4N)3PO4. The expected products of pyrolysis I would guess are

(Me4N)3PO4 >> Me3PO4 + 3 Me3N

Although it would be possible to instead see

Me3PO4 >> H3PO4 + 3 EtNMe2

by rearrangement of the ylide. Which rxn is preferred I'm not sure; energy barriers to both should be very high.

The metaphosphate might also be interesting if it can be made:

Me4NH2PO4 >> (Me4N)6P6O18 + 2H2O