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Sauron
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Lab Prep of Diethyl Sulfate
Searching for a bench scale prep of Et2SO4 is rather frustrating. The industrial processes are inconvenient or inefficient (or boyj) when applied to
small scale. This is not a new dilemna. A 1824 JACS paper comes to the same conclusion then goes on to propose and test a workable prep.
In that prep, a mixture of 95% ethanol and conc H2SO4 are dripped onto a heated bed of anhydrous sodium sulfate at 155-165 C and under aspirator
pressure so that the diethyl sulfate and some alcohol distill over to a receiver. The yield is 32 g after isolation and washing/drying.
Alternative dessicants gave lower yields, and neither anhydrous ethanol nor oleum were advantageous.
I have two questions, a narrow one and a broad one.
The narrow one: how scalable is this? I would guess it might scale 2-3X but at some point the heating of that bed of sodium sulfate is going to
become problematic.
The broader question is: are there any really biable alternatives that have come to light since 1924 or is this really it? Because if so it is
probably time to start shopping for this compound rather than making it, if one needs more than a hundred gm.
1. Stoichiometry
2 EtOH + H2SO4 -> (EtO)2SO2 + 2 H2O
From this is should be apparent that the charge of 50 g 95% EtOH is c. 1 mol and so ia the acid. The charge of sodium sulfate is 90 g The acid is
therefore in a 2X excess.
The yield is only c.40%
Offhand I would think that relocating the excess acid to the pot and preheating it with the sodium sulfate may be better, or at least more scaleable.
Attachment: ja01669a023.pdf (65kB)
This file has been downloaded 1720 times
[Edited on 7-4-2009 by Sauron]
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not_important
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I suspect that may be the best, based on that in the various organic prep books I've picked up over the years, post 1925 or so I don't remember seeing
such a prep and I do remember several noting they'd dropped it in this more recent edition because of commercial availability.
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Sauron
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How boring.
What about oxidizing the readily preparable alkyl sulfites?
I am all for commercial availability but I do like to keep my options open.
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Jor
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I don't have references for this, but how about a reaction of diethyl ether and oleum?
Just like dimethylsulfate can be made from dimethyl ether and oleum.
Or is you oleum to precious for this purpose?
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Sauron
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That does not work worth a damn on a lab scale, it is one of the industrial processes. Furthermore oleum IS too expensive, particularly in comparison
with conc H2SO4 and when considering the low cost of commercial ethyl sulfate.
See Merck Index, and the references at bottom of title page of the paper I posted.
The other main industrial proceses are ethanol and H2SO4, and ethylene and H2SO4 - basically are all variants on the ethyl hydrogen sulfate reaction
that is the basis for production of synthetic EtOH and Et2O.
ZVogel p.303 describes prep of alkyl sulfates from the anhydrous alcohol in question and chlorosulfonic acid. This provides the alkyl hydrogen sulfate
and HCl. Distillation of two mols of the alkyl hydrogen sulfate affords the dialkyl sulfate and H2SO4.
This is not very convenient where chlorosulfonic acid is not readily purchasable, as its preparation is from oleum and dry HCl, a highly exothermic
reaction and not for the faint of heart.
Furthermore Vogel warns of the toxicity of the alkyl sulfates and goes into the usual mantra already mentioned by not_important as found in many
texts, about how cheap the commercial product is and therefore how rarely one needs to prepare these in the lab.
Sartori describes the reaction of SO2Cl2 with 2 mols of methanol to produce dimethyl sulfate. But as his book deals only with military chemical agents
of the first World War he makes no mention of diethyl sulfate. It would be tempting to speculate that ethanol (2 mols) would react similarly with
sulfuryl chloride.
Sartori does describe ethyl chlorosulfonate as being prepared from ethylene and chlorosulfonic acid. I do not see why this would not also be
available from ethanol and SO2Cl2 (equimolar reactants) or why a second mol of ethanol would not obtain diethyl sulfate.
SO2Cl2 unlike chlorosulfonic acid is easily made in the lab from Cl2 and SO2 and so this route may be well worth a try.
[Edited on 7-4-2009 by Sauron]
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S.C. Wack
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This patent is similar and utilizes the well-known reaction of bisulfate with alcohol.
http://v3.espacenet.com/publicationDetails/originalDocument?...
The distillation occurs at a lower temp. and press. here.
If not high yielding, cheap.
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Sauron
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Thanks, S.C.
Patent is attached below.
The yield of ethyl hydrogen sulfate (ethyl sulfuric acid) is 87.4% and this is converted in a manner similar to the 1924 JACS procedure, i.e.,
dripping it onto anhydrous sodium sulfate but as you said, at 105 C and 5-10 mm Hg rather than 155-165 C and 25-40 mm Hg. Yield in the distillation
step is not specified but I would assume it is high till it is tested on the bench.
Very nice, and yes very cheap. 95% ethanol and what amounts to Sani-Flush. (But sodium hydrogen sulfate monohydrate is preferred.)
Best of all this is very nicely scaleable.
THIS NEEDS DOING IN A HOOD UNLESS YOU THINK BRAIN CARCINOMA IS FUN. DO NOT THE PEPPERMINT SMELL FOOL YOU. THIS IS A POTENT ALKYLATING AGENT! Gloves
and goggles, rubber apron all appropriate. Alkyl sulfates are readily absorbed through the skin. Conc ammonia will destroy spills.
Attachment: US3024263.pdf (156kB)
This file has been downloaded 1328 times
[Edited on 7-4-2009 by Sauron]
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Fleaker
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Seeing as perhaps I'm the only one in this thread who has actually made these alkylating agents on multiple occasions, both dimethyl sulfate and
diethyl sulfate, I would appreciate the opportunity to chime in on it. I know I've posted before on this with pictures too I think.
First off, I have to seriously suggest you just buy the damn stuff--it's dirt cheap. I have an illustrated synthesis literally sitting on my desk for
DMS and DES the corresponding alkyl iodides made from them, but I have decided against posting it.
I made DES and DMS the following ways:
1. Reaction of anhydrous MeOH or EtOH with XS 20% oleum (acceptable yield), must do aspirator vacuum distillation, oleum-intensive
2. Reaction of Me2O or Et2O with 20% oleum (best yields), aspirator vacuum distillation or careful aqueous workup, uses less oleum.
3. Reaction of MeOH with 18M sulfuric acid, straight distillation, no vacuum, much charring and mainly MeHSO4, not Me2SO4.
4. Reaction of excess EtOH and MeOH with sodium hydrogen sulfate (refluxed for 4 hours), isolation of the hydrogen alkyl sulfate salt and then dry
distillation with either Na2SO4 or NaHSO4 (water will co distill, to prevent, a small quantity of conc. sulfuric acid may be added).
It works quite nicely in the case of EtOH, not so well for MeOH but this is due to the workup. It's not supermely high yielding, but it's dirt cheap.
5. Reaction of MeOH with chlorosulfonic acid. Not as exothermic as the oleum, but decent yields of very acidic product.
Bear in mind that I did most of this months ago and empirically and didn't really consult the literature--just the MSDSs and some books on handling
such hazardous materials. All of these reactions scale well, particularly reaction 4 which is very cheap and works well when 700g of material is
distilled in a 2L flask. I worked on the .10 mol scale, and then the molar scale with a slight increase in yield observed in reactions 1-5. For
reaction two, which works quite nicely and comparatively cleanly (although there is still carbonization) I introduced the ethers as a gas through a
frit bubbler with the oleum. In all cases but 4, the reaction is EXTREMELY exothermic, be it alcohol or ether.
As far as I'm concerned, all of these processes will work on the lab scale. I personally advise against the use of oleum and chlorosulfonic acids as
it is an unnecessary expense and hazard. Also, and particularly with oleum, there is a lot of charring. This forms a porous cake of carbon that
strongly absorbs the product. It also is difficult to remove from the flask. Another problem with oleum and chlorosulfonic acid is that the product
will be highly acidic and must be washed to remove the acid components.
Frankly, I advise against making this in any fashion. If I absolutely had to make it and cost was no concern, I would bubble the ether through the
oleum as it is the cleanest. I wouldn't bother distilling it (loss of yield) when it can be obtained by careful, quenching of the spent oleum (which
ought to be H2SO4) with ice cubes. The DES or DMS will sink to the bottom of the cold acidic solution. Regardless of the method of preparation, if you
distill it moderate vacuum or not, expect a loss in yield due to carbonization. Also expect an annoying clean up.
If you're looking to make a couple liters or more, I suggest you simply make the hydrogen alkyl sulfate and drop onto the anhydrous sodium sulfate.
You can also dry distill the salt.
Brauer has a super simplistic approach for making sulfuryl chloride with activated carbon, but the method using camphor is superior as far as
throughput is concerned. Still, SO2Cl2 is again, quite cheap at $60/L.
I'll get more details when/if I can find where I put my notebook on all these alkylating agents.
Oh, I should probably also mention this neat tidbit...you can dry distill very dry sodium hydrogen ethyl sulfate with KI and get ethyl iodide. I
should probably follow up on that one...I don't recall seeing it reported anywhere.
I did all of these experiments in a large fume hood with a great draft, but I still was very uncomfortable and felt it was an inappropriate risk. I
had one mishap with the vacuum pump spraying DES onto my gloved hand out of the output side (I was distilling at 55 torr). I was too lazy to properly
trap the KNF Neuberger, figuring I could just clean it later by pumping ammonia.
[Edited on 7-4-2009 by Fleaker]
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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User
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Isn't this a drug related watched chemical?
Wondering if it is available without too many trouble.
What a fine day for chemistry this is.
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Sauron
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At my location, I cannot buy sulfuryl chloride, at any price, nor chlorosulfonic acid. Yes I can and have bought DMS, and can likely buy DES. Oleum I
can buy at absurdly high cost, I hate to mention how much I paid for 2 liters of 65% Merck oleum.
Anyway thanks for your experiences. \]
user, AFAIK alkyl sulfates are NOT on any DEA Schedule, NOT on List 1 or List 2, and no one knows what is or isn't on any informal watch list.
Furthermore many of us do not reside in the benighted USA and therefore fundamentally do not give a damn. These are alkylating agents with thousands
of uses having nothing to do with abuse drugs. You will note that the US patent S.C>Wack cited was assigned to the US government in the person of
the Secretary of the Navy. Do you think he's a drug cook? (The military use DES to make ethyl centralite, a propellant burning rate modifier.)
[Edited on 7-4-2009 by Sauron]
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Fleaker
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@User
I didn't know that it was watched, but I would not be surprised. If it's drug related, it's probably because it's an alkylating agent and could
possibly be used in making substrates that could go to illicit things.
@Sauron
It's a pity you can't buy SO2Cl2, but if you can get LSO2 and LCl2, it's a breeze and you can make enough to last years in an afternoon. Still, I'd
really just buy the DES. As for the chlorosulfonic...well there's always the oleum and HCl route. Might as well make some thionyl chloride while
you're at it :-)
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Jor
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AFAIk LSO2 and LCl2 are also unavailble for Sauron, if I understoof right.
I have never seen alkylating agents being controlled substances.
I would stay far away from DMS. Just about as toxic as conc. HF by skin contact, not to mention inhalation, wich is a hazard effeciently eliminated if
working in a fume hood though.
Im not sure about DES but it should also be very nasty.
Alkyl halides are less nasty. Are there many reactions where alkyl halides don;t work, and dialkyl sulfates do?
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Sauron
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As I have posted before, I make my own SO2 and Cl2 because I have no other option.
As for chlorosulfonic acid, I have yet to need any for any reason that I could not do better another way.
And I have spent a lot of time and effort to establish that there are far better ways to make SOCl2 than from oleum. In fact there is an embarassment
of such ways.
I'm not supposed to be able to buy DMS but it seems no one cares about that regulation here, same with Br2.
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Ebao-lu
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For DMS(dimethylsulfate) there is a known method with passing SO2 through methanol solution of some(dont remember exactly) Cu(2) salt i suppose CuCl2.
Then it should probably work with ethanol as well. Cu(2) could be recovered prob with air/catalyst(maybe passing SO2 along with air?) or by the same
Cl2/Br2 anyway there should be possibilities to improve this process
[Edited on 7-4-2009 by Ebao-lu]
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S.C. Wack
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Both article and patent mention US1411215. It claims 85% yields in the vacuum distillation. The two patents should've gone together really, so there it is.
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Sauron
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Thanks again S.C.
[Edited on 7-4-2009 by Sauron]
Attachment: US1411215.pdf (173kB)
This file has been downloaded 1180 times
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Panache
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May i ask why using these alkylating agents is somehow deemed prohibitively less dangerous than making them is. I say this as i get the impression
people are advocating buying them but not making them. Is there something to the manufacturing of them that perhaps has not been speciically divulged
that is unpredicatable or dangerous?
Also just as a help for people who may be considering making some, what is a sure fire method for destroying them. i would have thought dilute NaOH
solution or NaCarbonate, either can also be aersoled to clear out a lab in case of inadverdant 'vapourising'. I don'tt know though, just speculation.
And Fleaker, nice work on the dry distillation of KI and NaHSO4, i however understand your reticence on posting exhaustively on this topic.
edit-sorry sauron missed your conc ammonia comment re cleanup, i glazed over the moment you began using capitals, whoops, i should have realised you
are one of the few that use this typing style appropriately.
edit 2.1 just found this abstract sounds pertinent if someone has access tot he journal
http://www.cjche.ca/journal/issues/Feb%2001/Abstract%2054.pd...
[Edited on 10-4-2009 by Panache]
[Edited on 10-4-2009 by Panache]
[Edited on 10-4-2009 by Panache]
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garage chemist
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Fleaker, it's very interesting that you state that EtOH/Et2O + 20% oleum gives diethyl sulfate.
I once did an experiemnt where I reacted neat SO3 with an excess of absolute diethyl ether, and no diethyl sulfate was formed.
I slowly dripped Et2O onto solid SO3 with stirring and cooling.
After everything was homogenous, I poured all of it slowly into cold water, with lots of stirring. There only was a very small organic phase, and it
floated to the top. It turned out to be nothing more than residual ether. No diethyl sulfate seemed to have ben formed.
Reading Ullmann on sulfonic acids I found that combining EtOH with SO3 by slowly introducing EtOH into oleum with cooling, ethionic acid (ethyl
hydrogensulfate 2-sulfonic acid) is produced. This substance is miscible with water in all proportions, and was likely what I obtained in my Et2O +
SO3 experiment.
The reaction proceeds by elimination of water from ethanol, followed by addition of SO3 to the ethylene giving carbyl sulfate (a cyclic sulfonate
ester and anhydride) which hydrolyzes to ethionic acid.
http://v3.espacenet.com/publicationDetails/originalDocument?...
http://v3.espacenet.com/publicationDetails/originalDocument?...
How were you able to isolate diethyl sulfate from SO3 and Et2O or EtOH? Is it necessary to vacuum distill the crude mixture? Diluting the crude
mixture with water did obviously not work for me.
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Sauron
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g c, DES and EtOH are immiscible as shown in the JACS paper on preparing DES from heated bed of sodium bisulfate monohydrate. The layers are easily
separated with a sep. funnel, no Et2O forms under conditions described, and distillation inadvisable due to decomposition. Wash as described, dry, DES
will be clean and neutral. See also US Navy patent.
[Edited on 10-4-2009 by Sauron]
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Nicodem
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As far as I know, diethyl sulfate (just like dimethyl sulfate) is miscible with just about any organic solvent. I really can not see why it would not
be miscible. Utmost I could imagine it is not fully miscible with petroleum ether, but with anything more polar than that it simply must be. Dow's
product page says:
The same page also claims Dow chemicals uses the "fuming sulfuric acid in ethyl ether or ethyl alcohol" production processes. Therefore they probably
have some very old patent on the topic.
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scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
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garage chemist
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Quote: Originally posted by Nicodem  |
The same page also claims Dow chemicals uses the "fuming sulfuric acid in ethyl ether or ethyl alcohol" production processes. Therefore they probably
have some very old patent on the topic. |
That is remarkable. They must use a special method that I am not aware of. I can attest that simply combining Et2O and SO3 does not directly give any
diethyl sulfate!
Perhaps the crude mixture must undergo some sort of thermal treatment to effect the formation of DES.
Sauron, firstly DES is completely miscible with alcohol and other polar organic solvents, and secondly, I've done the patented method of DES
preparation using sodium bisulfate and ethanol myself. It indeed works, but is very low-yielding (under 15%!) and involves vacuum distillation of the
crude ethylsulfuric acid over Na2SO4 (distilling ethylsulfuric acid in vacuum without any additives causes lots of decomposition and little DES
formation. Na2SO4 is required to bind the H2SO4 byproduct as NaHSO4.).
The method in the JACS article that you posted in the first post would be much preferable since it just involves mixing H2SO4 and ethanol prior to the
vacuum distillation instead of prolonged reflux of EtOH with NaHSO4.
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Nicodem
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As I understood, you added Et2O to SO3 which is not exactly the same as adding Et2O to H2SO4. Et2O gets protonated by H2SO4 (pKa of Et2O is about
-3.5) and thus an SN2 reaction can proceed between protonated ether and hydrogen sulfate ions (which are otherwise notoriously non-nucleophilic). With
SO3 you can not have the same reaction pathway. Although SO3 is also electrophilic and it should also coordinate with Et2O, but perhaps the subsequent
reaction is not so rapid, requires heat, or the intermediate succumbs due to elimination/sulfonation reactions. I don't know, but certainly I would
not generalize your experiment with the reaction of H2SO4 with Et2O.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Sauron
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In the JACS article, which teacher dripping a mixture of 95% ethanol and conc H2SO4 onto sodium bidulfate in a flask evacuated to aspirator pressure
and condensing, states and I quote:
"The distillate, which consists of alcogol and diethyl sulfate in two layers, is separated by means of a funnel."
That is not consistent with miscibility in all proportions...?
[Edited on 10-4-2009 by Sauron]
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Panache
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| Quote: Originally posted by Fleaker |
Oh, I should probably also mention this neat tidbit...you can dry distill very dry sodium hydrogen ethyl sulfate with KI and get ethyl iodide. I
should probably follow up on that one...I don't recall seeing it reported anywhere.
[Edited on 7-4-2009 by Fleaker] |
Sorry what is sodium hydrogen ethyl sulphate, i assume you meant ethyl sulphate, which could also be called hydrogen ethyl sulphate, instead of
diethyl sulphate, but i'm not sure.
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Sauron
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I think he means the sodium salt of ethyl hydrogen sulfate
Na replaces H in the -OH
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