Ethyl hydrogen sulfate

[foxy2]

Ethyl hydrogen sulfate can be neutralized with NaOH to get sodium ethyl sulfate which can be used in the synthesis of nitroethane on Rhodiums site.  This is the diethyl sulfate synth halfapint brought up in

Post 208329

(halfapint: "Re: OTC preperation of Dimethyl sulfate?", Tryptamine Chemistry).  It looks like adding some anhydrous sodium sulfate will increase the yeilds for this synthesis.

Synthesis of diethyl sulfate.     Wu, Zhiguang; Zou, Zhichen; Huang, Ruqi.    Dep. Chem.,  Shandong Teachers' Univ.,  Jinan,  Peop. Rep. China.    Huaxue Shiji  (1991),  13(3),  190, 144.  CODEN: HUSHDR  ISSN: 0258-3283.  Journal  written in Chinese.    CAN 115:158460    AN 1991:558460   

Abstract
Stirring 95% EtOH (excess) with concd. H2SO4 in the presence of Na2SO4 at 25° gave 98.8% EtOSO3H which was heated at 125-140° under reduced pressure to give 87.2% Et2SO4. 
Do Your Part To Win The War

[foxy2]

Based on this article I think the Na2SO4 in the above synth serves as a drying agent to increase yeilds.

Esterification of ethanol with sulfuric acid: a kinetic study.
    
Theodore, Shammi; Sai, P. S. T.     
Can. J. Chem. Eng.  (2001),  79(1),  54-64. 

Abstract
Expts. were conducted in a stirred batch reactor under isothermal conditions for obtaining kinetics of the esterification reaction between ethanol and sulfuric acid.  Reactive adsorption technique was employed to enhance the conversion.  Anhyd. sodium sulfate was used as an adsorbing agent to remove the water formed during the reaction.  The variables include the mole ratio of ethanol to sulfuric acid, reaction temp., purity of the reactants, and the amt. of adsorbing agent.  The reaction was found to be reversible and second order at low mole ratios, and irreversible and first order at high mole ratios.  The kinetic parameters of the rate law were estd.  A possible reaction mechanism was proposed and validated with the exptl. data.  The effect of the mole ratio of reactants, anhyd. sodium sulfate loading, and purity of the reactants on the yield of Et hydrogen sulfate was studied, using full-factorial search and optimized conditions were obtained by the method of steepest ascent.  More precise optimum conditions were obtained using the Box-Wilson composite method. 
Do Your Part To Win The War

[foxy2]

This may bee a good alternative if one of the local russian bee'z could look this reference up?

Oxidative sulfuration of alcohols in the presence of cupric chloride.    

Golodov, V. A.; Panov, Yu. I.
Kinet. Katal.  (1983),  24(5),  1276-7. 
Journal  written in Russian.   

Abstract
The title reaction of ROH (R = Me, Et) with SO2 and CuCl2 was 1st order in each reactant, and gave the corresponding (RO)2SO2 under mild conditions. 
Do Your Part To Win The War

[Antoncho]

Yummmmmmmmie!!

Foxy, oh Foxy! My words fade compared to my feelings... SWIM's been waiting for this a long, long time.

I can't promise you that we can find this reference - in fact, there's only like 3 or four of us at HyperLab that have an access to the library - and they all are disgustingly slothy, and the journal is not common afaik. But i'll try to kick'em as hard as possible.

Maybee, just to try it and see if it works... There's quite a number of variations possible as to the cond's though. Well - Antoncho's gonna work on this issue - that's all he can say by now.

Antoncho

[UTFSE]

Diethyl sulfate preparation is on Rhodium page - been there over a month.

Substituting methanol for ethanol results in Me2SO4. according to Rh.
always appreciate your time and consideration

[foxy2]

Well this thread has some possible improvements.  Adding NaSO4 supposedly increases yeild.  I guess you prefer to stick with 50% yeilds, thats fine with me, others may want something better.

Also if you are looking for nitroethane this shows approximately how NaHSO4 can be prepared in close to stoichoimetric yeild.  Then you can go on to preparing nitroethane from an easier to make precursor.

Ya know what I see a meth syth on Rhodiums page too, maybee everyone here should just quit discussing meth because hey its already at Rhodiums page so there is nothing else to talk about!!!


Do Your Part To Win The War

[Antibody2]

deep breath foxy, btw - you on vacation? or transfered to a research library? you've become the fount of awesome posts lately  

keep it up
"All those memories lost like rain..."

[halfapint]

Using only the information foxy2 posted in

Post 216477

(foxy2: "Dimethyl/Diethyl Sulfate", Chemistry Discourse), "The title reaction of ROH (R = Me, Et) with SO2 and CuCl2 was 1st order in each reactant, and gave the corresponding (RO)2SO2 under mild conditions", I produced DMS in 66% yield from methanol, with cupric chloride bubbled by SO2. I have high praise for this method; if you can handle using dimethyl sulfate at all, this is how to get it.

Working outdoors out of respect for bad fumes, I generated SO2, by heating sulfur in sulfuric acid, from an Erlenmeyer on the hot plate. I was pleased to find that this generation is well-behaved, easily controllable by temperature, and sustainable for hours without refreshing the charge. I used the gas exhausted from the DMS vessel by bubbling it into hydrochloric acid, in hopes of coming up with some thionyl chloride in HCl. Neither that, nor the diethyl sulfate run which followed the DMS in the same apparatus arrangement, has been worked up yet. (Reduced pressure distillation at the aspirator must bee used, for neither DMS nor diethyl sulfate will stand up to atmospheric pressure distillation --- as if you'd want to!) Indications are, however, that product was formed in each case. I'm pleased as punch. << >> This one's a lot cleaner than the other methods I've tried.

(I interpreted "mild conditions" as meaning warm alcohol, 30° to 40°C, supposing room temperature might have been stated as such in the abstract. The alcohol vessel was kept in a warm-water bath, which was refreshed periodically with a pot of water out of the coffee-maker.)
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

[Antoncho]

Excellent! I admire thy work, Half-a-Pint!

Could you bee just a little bit more specific? As to, you calculate yield based on CuCl2, right? How much DMS did you get?

Your report is truly valuable (esp considering SWIM nad no luck tryin' to make the subj  by bubbling Cl2 into SO2 conc solution in MeOH.)

Now he's really glad.

Thanx,


Antoncho

[foxy2]

Sweet
I aways like to see someone make use of the ref's I dig up.
 
Foxy
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[halfapint]

you calculate yield based on CuCl2, right?

No, Antoncho, I meant 2/3 of my methanol was converted into DMS! That's why I was so happy. Based on just the amount of methanol reacted, and not recovered in the end, yield must have been very high -- only ~3 ml of oily residue was left undistilled. Since the solid copper species left in the flask was green, I supposed it was unreduced cupric material, meaning the CuCl2 played only some kind of catalytic role, rather than serving as an oxidant consumed by reduction. I failed to check out this supposition, discarding rather than analyzing the residue. On addition, the CuCl2 was not completely anhydrous, for some green still showed. While gassing, the solid material seemed a white precipitate, beneath the dark green alcohol which had a transparent quality.

When you ask me to get more specific, you should bee sure you know what you're asking for. I have been called "wordy" by some. Since quantities just aren't critical, and since 1st order means it isn't reversible, there's little to discuss there; put more in, get more out. Also, my grasp of theory isn't deep enough to tell you what went on inside this reaction. So if you ask me for more detail, you are likely to get a vivid literary description of how I spent my morning, together with my emotional reactions to each phase of the process. Are you sure that's what you wanted to know about?

OK -- in the workup, I distilled methanol at atmospheric pressure, venting vile vapor through a tube from a vacuum adapter leading out the window, until the vapor temperature rose to 76°. Without stirring, I could see the surface, which showed an anomoly: all the time methanol was coming over at 2-3 drops per second, temperature 60°-70°, there was no ebulliation in the flask, it wasn't bubbling. At the time the temperature began to rise, when I shut down the distillation, patches of a skim began to appear on the surface of the green liquor. This must have been copper salt coming out of solution as its methanol phase was exhausted. Briefly I entertained a fantasy, that it might have been made from some particles of filterable sulfur, but to have got through the glass filter I used, they would have to be ultra teeny weeny.

I let the solution cool nearly to room temperature, then added 5 silica gel beads as boiling stones, to prevent bumping. Then I proceeded with the low-pressure phase of the distillation, with the water aspirator. The bulk of the material was still in the flask; as I said, almost all of that was DMS. This was verified by methylation of hydroquinone, to para-dimethoxybenzaldehyde.
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

[Antoncho]

   

Half-A-Pint, but that's plainly impossible!

Sulfur in SO2 has a +4 state of oxidation, whereas in DMS it has a+6 charge. So there absolutely must bee smth. to oxidate it!! If you say that Cu color stayed green all the time - then, obviously, it wasn't reduced, huh?

I wonder if there possibly is a typo in the abstract and it is dimethylsulfite that one gets in this rxn?

Foxy2, can you certainly say that the article said "sulfate"?

Half-a-Pint, can you describe in all possible precision the physical prop's of the product you've got? Dimethylsulfite boils at 127 at atmospheric pressure and it has a specific gravity of 1,29 g/cm3.

DMS is somewhat heavier (1.33 g/cm3) as well as higher-boiling (189 C - but of course, w/decomp'n - i wonder if the former also decomposes at its bp?)

Also, what do you mean by p-dimethoxybenzaldehyde?

Yes, dimethylsulfite is also a good methylation agent. The leftover aqueous phase from methylation - do you, by chance, have a sample of it left? If you do, or methylate smth. else w/the product you've got, please, try to acidify the remaining liquor and smell it for presence of SO2.

How much product, in mls , you got from how much MeOH?

Antoncho

[uemura]

Half-a-pint and Antocho!
First, Uemura is impressed of this method to get a methylation agent. Now

Half-A-Pint, but that's plainly impossible!

To add some simple calculation:
1) Suppose the CuCl2 is not changed in the rxn and
2) everthing is anhydroneous and
3) 100% conversion of MeOH takes place

Then only two possibilities can happen:
1) ROH + ROH + SO2 -> R2SO4 + H2 or
2) ROH + ROH + SO2 -> R2SO3 + H2O.

1) seems a bit unlikely, 2) makes more sense. But this would mean Antocho is right, it is the Dimethylsulfite which seems to be produced.

foxy, could you check if your reference say 'sulfite' or 'sulphate'?

Carpe Diem

[halfapint]

The solid copper precipitate went white in the course of the reaction; it could have been re-oxidized at the end of the final distillation, to turn it back to green. Thanks for pointing out the change in oxidation states, which helps me to understand this reaction better.
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

[Rhodium]

Antoncho: p-dimethoxybenzaldehyde = para-dimethoxybenzaldehyde = 2,5-dimethoxybenzaldehyde

[foxy2]

It was cut and pasted so I am positive thats what it said.

Noone has thought about pH implications?
Maybee they buffer it to run under mildly basic conditions whereby the excess hydrogens ca bee gobbled by the buffer.  There are more than the two possibilities umeura suggested.
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[Antoncho]

2 Rhodium:      yes, i was just wondering how Half-a-Pint managed to make that by methylation of hydroquinone

2 Half-a-Pint: soooo.... i still think it's DMS'ite - the copper salt turning white could just mean it serves as a catalyst - the extra chlorines being constantly 'in use' throughout the rxn.

What do you say about the bp of the product? Could you,by chance, try to boil it outdoors and see if it heats beyond 130 C?

2 Foxy: whaddayamean? Hydrogens eaten up by a buffer? Well, then it should bee H+, not H2, right? I mean, where do the extra electrons go? If only we could have that article...[sigh]

Antoncho

[halfapint]

The "benzaldehyde" was a mis-statement. Meant dimethoxy-benzene, which has a trivial name I don't remember either. Count that as a spelling error.

A repeat run was sabotaged by _suckback and much of the apparatus is in other use at the moment, but the presumptive diethyl sulfate is yet undistilled. Excuse the furor raised by my (1) grammatical error, saying benzaldehyde when I didn't mean it, and by (2) my incorrect guess, that the cupric chloride does not serve as oxidant here. The reaction works as stated, I'm sure the dialkyl sulfate was formed. It's a substance I have distilled before, and it showed its familiar behavior in the distillation, after the "quasi-sublimation" of the methanol. In breaking down a still, you often get a whiff of odor. DMS smell you don't forget. I just didn't state the specifics of the reaction right.

Since this reaction must bee an oxidation mediated by cupric chloride, there ought to be a way to regenerate this species to attain a higher turnover of copper. SO2 can serve as an oxidant, as when it bleaches straw hats in Panama. Could some of the white solid material in the gassing have been finely divided sulfur?

Are there no reduced copper species, or methanolates or dimethylsulfate complexes showing a green coloration, to explain the re-greening of the solid residue near dryness? If the final residue did include sulfur, that would explain how a copper (II) oxidation state could have been maintained throughout, by reduction of SO2 to sulfur, regenerating the CuCl2. Like you said, Antoncho, the chlorines don't get away.

And, uh, who says the dimethyl sulfite is also a good methylating agent? Would that mean, possibly, that trimethyl phosphite would also serve as a good methylating agent? Come on, I collect these things.
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

[halfapint]

Did Half-a-Pint stumble into a correct answer for once? So if a run of this formulation has filter isolation of sulfur, I guessed it right, and the SO2 is refreshing the copper in its high oxidation state. If I read enough of my old books, I could calculate the relative oxidation potentials, to see if cuprous chloride in methanol could reduce sulfur dioxide to sulfur. Or perform the experiment, which is just to repeat the run, and record every measurement. Which was my job all along.

Should somebody do this with me, I won't bee jealous. I got my cupric chloride by mixing cupric sulfate (CuSO4*6H2O, tree root killer for sewer lines) completely dissolved in hot water, with a hot water solution of calcium chloride (CaCl2, driveway de-icer), sedimenting, decanting, filtering, boiling to dryness. Amounts were equimolar. Color change was blue to green. (Residue heated only sufficiently for drying, the yellow "dried" material darkens with generation of bad gas on overheating.) My sulfur was soil sulfur; my sulfuric acid was drain cleaner. My methanol was distilled from windshield washer concentrate, from the oil company with the seafood symbol. Won't take you too long, to check on what I'm saying. I say you can make dimethylsulfate that way, easier than any other way, and far more satisfactory in terms of scale.

Edit: Filtration of the failed flooded run shows a small amount of water-insoluble white powder. There it is, beez. Anybody finished the redox calculation yet, to see if it's possible?    (Must allow the alternate possibility, though, of sulfur sublimation from the SO2 generator.)

[Antoncho]

! ! !

Wow. Is it true?

SWIA could perform this experiment too, having all available ingredients at hand - the only 2 things that hold him back are - 1) he lacks a vacuum distillation facility and 2) he's really afraid of working w/DMS, even having a small fume hood  

But this is too tempting so he might eventually give it a try (partially, to see w/his own eyes how it works and possibly finding out the reason why).

The weird thing is that sulfur in your proposed equation is both being reduced and oxidized at the same time! Of course, looking closer at it, there turns out to bee nothing wrong: Cu²⁺ oxidizes SO2 to SO3, while Cu⁺ reduces it to S... Would bee really interested about that electropotentials data...

Say, Half-a-Pint,could you recommend some way of purifying, or at least sepaprating the DMS from the rxn mixture w/out vacuum distillation? SWIM doesn't even have a source of running water, so that's out of question for him

And one more question: for how long did you gas your methanol and was there much SO2 escaping?

Sincerely,

Antoncho

[halfapint]

Well, Antoncho, after you take your excess methanol off, you have left a heavier, more viscous fluid, mainly composed of DMS. But, pardner, it's green. The presence of copper, we may note, does some tricky things. It could easily complicate your methylation reaction. Afterward, you should easily bee able to separate your organic component -- if the methylation works...

I heard your part of eastern Siberia was really civilized. The wild East. Like everywhere else: too much development, too many left out. To get water pressure, if you have a suitable rural location/situation, I suppose you'll have to build a water tower. Then an aspirator could work at your place. When you explain all this to your significant other, I'm sure she'll approve your hydrology project.

I gassed 5 hours the first time. The exiting SO2 had very little pressure, for bubbles into the final HCl solution were rare. Except when I poured a coffeepot of hot water over the methanol vessel, to re-establish my "mild conditions", when the HCl was bubbled vigorously. Examining the second run, with 4x the copper concentration, I noted the bubbles were quickly almost consumed before reaching the surface.
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

[Antoncho]

I heard your part of eastern Siberia was really civilized. The wild East. Like everywhere else: too much development, too many left out. To get water pressure, if you have a suitable rural location/situation, I suppose you'll have to build a water tower. Then an aspirator could work at your place. When you explain all this to your significant other, I'm sure she'll approve your hydrology project.

        LMAO! I understand you meant it as a joke, but i still feel oblidged to clarify on this - at least once on this board (yeh, a wrong forum, i know). Perhaps the mods will forgive me for offtopic.

My part of Eastern Siberia is just as civilized as any its other part, as well as any other part of the country. We do have waterpipe system , as well as anything else you could expect to meet in a city - the only visible difference between where i live (near Baikal lake - maybee you've heard of it) and an ordinary Northern US city w/population of ~600,000 is the fact that the closest other 'big' city is situated some 1000 kilometers to the West , and in the space between them there's basically nothing. A vast sea of uninhabited space covered w/forest.

The reason SWIM doesn't have a source of running water is simply his sharing apartment w/the rest of his family (that's very common here as renting or buying a place to live is very expensive) - every single member of which hates his chemistry with passion  - mainly beecause of odour  - and won't tolerate its presence anywhere else than in SWIM's bedroom. In which there is no source of running water    

So... guess you'll say SWIM's crazy to do chemistry where he sleeps, but
a) he constantly vents the room
b) he takes all possible precautions, including the fume cupboard that he built from whatever the Fate had sent him - not exactly a water tower, but still quite something!    

Now to the chemistry. As i said, this project of yours, dear Half-a-Pint, absolutely rocks and it's been quite some time since i've been so exhilarated about something!

Say, would it bee possible, you think, to remove the residual copper salt by simply washing DMS w/water? To swim it seems OK - even though some DMS will also dissolve. After all, it can always back-extracted (although i doubt SWIM would want to do that!)

Maybee - just in case if you plan another trial  - you could check that suggestion on a coupla milliliters of your DMS? Please? Just mix it with an equal volume of water, shake until homogenous and see if the color goes to the top layer? That would mean really something for SWIM!

Another, although much less appealing, alternative would bee to dissolve DMS in benzene and wash the solution several times - that is bound to work, i think.

And - dear Half-a-Pint - Antoncho prays you! - do a detailed write up - with all the weights in grams, temps in degrees and times in hours! That way your xperience will not only bee much more reproducible, it will also certainly immediately make it to Rhodium's page.
You didn't even tell us how much DMS you actually got!

Well, i guess i'm done for now - and i'm really looking forward to hear more from you

As ever,

Antoncho

[uemura]

half-a-pint!

Should somebody do this with me, I won't bee jealous.

You give Uemura a hard time, half-a-pint. First, your sodium-phosphite/CuCl2 (*) method for the trimmethylphosphate looked so much better than the Uemura P2O5 approach. Having finally all bits and pieces for this rxn together, you now invite Uemura to use his CuCl2 (**) to make DMS   .

Not having as much concern as Antocho has with respect to the DMS toxidicy (Uemura has reasonable semi-prof lab equipment and has long time ago blown out 500ml RB with metyhlation in progress -wasn't that much nice-) he still isn't sure if DMS is much superior to trimethylphosphate. He thinks DMS is just always used because it is cheaper and it is easy available to professional chemists.

When joining and chross-checking your rxn, Uemura would prefer to generate the SO2 from NaSO3 and H2SO4, followed by drying over CaCl2 (***). Questions: what was the molar amounts of MeOH, CuCl2 and SO2 used in your rxn? Anything warmed up / refluxed?

Uemura will consider to verify your method!
(*) This CuCl2 catalised rxn looks anyway very similar to the method discussed here.
(**) uemura fully confirms the method for the CuSO4/CaCl2 -> CuCl2/CaSO4 followed by just boiling away the water to get the brown anhydroneous CuCl2 salt.
(***) Would it be better to bubble thru H2SO4?

Carpe Diem

[otto]

indeed halfapint,

otto prepared some copper-(I)-chloride a while ago. this is a white solid, insoluble in water or methanol. upon exposure to air it turned green very quickly, especially when humid.

otto has strong believe that your green residue is some copper(II)-oxychloride or -hydroxychloride (which isnt soluble in water, check with your precipitate!). you should be able to dissolve it in HCl, bubble air into the solution (or H2O2) to reoxidize any remaining copper(I)species and you end up W/ a solution of copper(II)-chloride in HCl.

a suggestion, otto isnt sure of: mix your green copper-residue (after giving it some time to fully get oxidized by exposure to air, preferably with some water as oxidation will be faster then) with an excess (say: 5 times) of NH4Cl and heat it until no more NH4Cl-fumes will come out. you should end up w/ dry CuCl2.

otto

[uemura]

Good Morning Half-a-pint,

Uemura again comes up with questions where he wants to join the requests of Antocho. It would bee helpful to provide us with some quantitative figures for the rxn, espec. the amount of CuCl2 used in the method.

One of reasons why Uemura may want to repeat your experiment is that methylation of gallic acid with trimethylphosphate was found to be only 50% as effective as with DMS (which he did succesfully long time ago).

All bees would appreciate your inputs!
Carpe Diem

[Antoncho]

A Hyperlab friend of ours, Diafrag, retrieved the original article on CuCl2 oxidation by Golodov and Panov. There isn't a single word on any disproportionation or anything like that in it - they plainly state that CuCl2 is an oxidant.
They state the rxn equation as:

2ROH + 2CuCl2 + SO2 ---> (RO)2SO2 + 2CuCl + 2HCl

R=Me, Et. It goes equally well w/both.

The article deals mainly w/kynetics , so the yields or some such aren't given.
The xperimental details are: 30 C, SO2 and MeOH aren't crucial , however, they measure the rxn kynetics at SO2=100% vol. of MeOH. That is, not much at all??? CuCl2 concentration 0.05-0.2 mole/liter. Time not specified.

?

Maybee, smth different happens when you use a very large xcess of SO2???

Also - Half-a-Pint, a thought occurred to me that some of your DMS that was left in the flask after didtilling off MeOH might actually have been HMeSO4 - which was converted to DMS anyway after distillation. If you ever do it again, PLEASE, check the initial (pre-distillation) product's water solubility!

Antoncho

[halfapint]

When I got back to Hive this time, took me a while to find this thread. And my notes are scrambled, so from memory: yield on my 3rd run amounted to 78% calculated on the basis of CuCl2. No metaphysical reoxidizing happened, the copper was reduced. Yes, about 2/3 of my methanol became DMS, like I said, but that was an artifact of the amount used. The cuprous precipitate does whiten in its reduction. I also did have a small amount of sulfur sublimation, since no trap was used in the SO2 line. This has AFAIK no effect on the reaction, still maintain no trap is needed, for any vapor from sulfuric acid is dry. I reiterate, this is the cleanest generation for dimethyl sulfate I know: cheap, easy, efficient, low hazard, low fumes. Diethyl sulfate was also obtained in this way, but that run has not been repeated for quantitative reporting.
a half a pints a half a pound a half a world a half a round
Sidearm n. Flask neck tube.

[Antibody2]

hi halfapint

i like you rxn, i have a question though, something i haven't been able to puzzle out on my own, perhaps you can enlighten me.

you got 78% yeild based on CuCl2, yet CuCl2 and MeOH are consumed in equimolar proportions, so by my calculations if 66% of the MeOH (2M let say) was converted (42g) that would require 176g CuCl2, if your yeild based on CuCl2 was 78% that means you used 225g of CuCl2.

I don't understand how you dissolved you dissolved 225g CuCl2 in that minute amount of MeOH (64g). Was it added in portions with the reduced CuiCl being filtered?

2M MeOH = 64g
2M CuCl2 = 268g

[Antibody2]

otto has strong believe that your green residue is some copper(II)-oxychloride or -hydroxychloride (which isnt soluble in water, check with your precipitate!). you should be able to dissolve it in HCl,

the residue after distillation is indeed insoluble in MeOH as well as H2O, but is easily digested by 31%HCl, for whatever that is worth. Further, after the SO2 generation is finished, if the flask is allowed to sit overnight the precipiattion of the copper byproduct increases considerably, i don't know if just takes a long time to crustallize or if the rxn continues for some time after the SO2 generation stops.

[Mountain_Girl]

Patent GB581115

:

Alkyl sulphates wherein the alkyl radical contains not more than four carbon atoms are prepared by heating sulphuric acid with an aliphatic alcohol containing not more than four carbon atoms, preferably at a temperature of about 80  to 120 °C, passing a stream of an inert gas into and through the reaction mixture to entrain in the vapour phase water and alkyl sulphate formed by the reaction, removing the issuing gas stream laden with water and alkyl sulphate vapours and recovering the alkyl sulphate from the gas. The process may be carried out in a continuous manner in a system involving a reaction vessel interconnected with a condenser, a receiver and a gas pump, by continuously or intermittently introducing into the reaction vessel sulphuric acid and the aliphatic alcohol, heating the mixture therein to a temperature between 80 and 120 °C, continuously injecting a stream of an inert gas into and through the reaction mass and continuously moving the issuing gas stream laden with water and alkyl sulphate vapours into the condenser where the water and alkyl sulphate condense, whereupon the gas stream is reinjected into the reaction mass, the pump recirculating the stream of gas through the system to thereby continuously remove the water and alkyl sulphate formed. The condensate in the receiver forms two layers, whereby the alkyl sulphate may be separated and recovered; the water layer containing some ethyl hydrogen sulphate may be concentrated and returned to the reaction vessel. Preferably, the reaction is commenced and maintained with the sulphuric acid in excess of molecular proportions, for example an initial ratio of between 2 : 1 and 1 : 1 is suitable, followed by addition of alcohol and acid in a 2 : 1 ratio to balance the consumption in the reaction. Methyl and ethyl alcohol are preferably reacted at a temperature of 100 to 105 °C and the propyl and butyl alcohols at 90 to 95 °C. Inert gases specified are air, carbon dioxide, hydrogen and nitrogen. Examples illustrate the preparation of ethyl sulphate and methyl sulphate by the continuous method described above.

[Antoncho]

All i can say to this is:

WOW!!!

WOW!!!

WOW!!!



M_G, you have just provided us with a completely OTC synthesis of all imaginable alkylating agents! I mean,.... Oh well...


Now, this synthesis is DANGEROUS. Dialkyl sulfates are deadly carcinogenic compounds and a great care must bee exercized.

The only real obstacle in performing this synth i see is the need for thorough mixing of the reagents. Some real vigorous stirring or shaking, probably... Can you fit a mechanical stirrer into the rxn flask so tightly as to prevent ALL leaks thru which DMS-saturated vapours will escape into your atmosphere?


Any other suggestions?


Very good, M_G, i didn't hope to ever see such a synthesis! (and it's good that i didn't know about it a year ago, i would've already poisoned myself     )




Antoncho



P.S. Oh, yeah. DMS's azeotrope w/water: bp 98 C, 27% DMS.

[moo]

I'm impressed... It is beautiful!

You could make a paraffin-sealed stirrer as there seems to be no risk of pressure changes. It could happen if someone managed to close the system somehow, but that would be a catastrophe anyway. Some people might just settle for sealing a grass stirrer shaft with telfon tape, with careful testing of course.

[Antoncho]

Hey, beez. 1st of all, here's a quote from the patent text: "...or the reaction vessel can bee filled w/Raschig's rings, in which case stirring is unnecessary".

So, you see that there's at least 1 solid way to make things easier (can anyone think of an OTC substitute for Raschig's rings? )


Then, if you remember what the patent says, the rxn represents a classic case of an equilibrium rxn. It is precisely the removal of BOTH water and dialkylsulfate from the rxn mass which makes it work.

So i suggest the following:

Combine equal volumes of toluene and HAlkSO4 of your choice. Add an xcess molar amt of some drying agent that is capable of holding water at 100 C. Place the flask into boiling water w/frequent stirring or shaking. When (that is, IF) the phases disappear, cool and decant the upper layer (hopefully, the salts will settle).

Alternatively, chill the stuff in freezer and wash out the salts w/ice-water (dialkyl sulfates, esp. DMS, are readily hydrolyzed w/aqua, but at this temp the losses should bee negligible). Dry the mixtr while still cold (here, again, we need a drying agent that will suck water at LOW temp) and strip off tolly (actually, this toluene solution can bee used for methylation as is, but stripping it off from the resulting product will bee more ruinous to the enterprize).


Sounds complicated? Well, but you don't have to

a) buy an air pump
b) risk breathing DMS

To summarize said above, SWIM has quite a bit of xperience in ghetto chemistry (i assume, if one can't get DMS, you probably works in ghetto conditions, right? ) and he knows that he wouldn't want to build a potentially non-hermetic vapor-phase system for production of such substances...



I have a big question for everyone: does anyone know what drying agents hold water at >100 C? And how many molecules of water they bind? Namely, what do you think of MgSO4 and CuSO4?





Antoncho

[Vitus_Verdegast]

So, you see that there's at least 1 solid way to make things easier (can anyone think of an OTC substitute for Raschig's rings?)

What about glass tubing cut in 1/4 pieces with a glass file?

[Aurelius]

That works fine, just don't go trying to use diazomethane with it

[lugh]

Flame annealing of each edge will solve that problem  

[Aurelius]

And I thought typing patents sucked!

[Vitus_Verdegast]

They're not hard to get, if distilling your own booze is legal in your country   . Look for online brewery and distillery supply stores.

[Mountain_Girl]

Antoncho, the wild enthusiasm of your posts is always entertaining and contagious to me  

Thoughts:

* What I find strange about this method is that the more volatile alcohol is not preferentially entrained in the gas. The initial conversion to the HAlkSO4 is itself an eqbm reaction, which means there will be unreacted alcohol present to be volatilised. I guess this step lies enough to the right so that the method remains effective overall. However it would still make sense to me to slowly drip the alcohol into a large excess of acid so that most of it is converted before it can be carried away.

* When the patent refers to Raschig rings I believe what they really mean is a packed bed through which liquid and vapor are passed counter currently, a common industrial practice. Rachig rings and other forms of packing are used to increase the liquid/vapor interfacial area but I don't think they would be effective in a static medium, i.e. simply sitting in a reaction flask.
Personally I expect that the agitation supplied by the bubbling of gas will be sufficient.

* To further improve yields I would suggest charging the reactor with dried alcohol, and passing the carrier gas thru conc. H2SO4 1st.

* Combine equal volumes of toluene and HAlkSO4 of your choice. Add an xcess molar amt of some drying agent that is capable of holding water at 100 C.

Instead, perhaps you could remove the water by distilling off the toluene/water azeotrope, and replenishing with dry toluene as it is removed ?
Also, a product of the decomposition of HAlkSO4 to (Alk)2SO4 is H2SO4 which...wait - if u have the HAlkSO4 then surely dewatering is not the issue ..the reactions are:

1) AlkOH + H2SO4 <---> AlkHSO4 + H2O 
2) AlkHSO4 <---> (Alk)2SO4 + H2SO4

Dewatering drives the 1st reaction not the second ??
Me confused or u confused ?

[moo]

Instead, perhaps you could remove the water by distilling off the toluene/water azeotrope, and replenishing with dry toluene as it is removed ?

Using a Dean-Stark trap or even plain distillation setup sounds like a good idea, but having H₂SO₄ around with toluene might lead to formation of toluenesulfonic acid, which as water is removed might react to the alkyl toluenesulfonate. But removing water from the receiving flask with this kind of setup could be fruitful, although there are other separators in the existence as well.

Also, a product of the decomposition of HAlkSO4 to (Alk)2SO4 is H2SO4 which...wait - if u have the HAlkSO4 then surely dewatering is not the issue ..the reactions are:

1) AlkOH + H2SO4 <---> AlkHSO4 + H2O
2) AlkHSO4 <---> (Alk)2SO4 + H2SO4

Dewatering drives the 1st reaction not the second ??
Me confused or u confused ?

Formerly I thought that the monoalkyl sulfate reacted with another mole of alcohol, but given the fact that dimethyl sulfate can be vacuum distilled from monomethyl sulfate, I guess the patent is right on this point. Removing the water drives the first reaction.

[Mountain_Girl]

Good point about the toluenesulfonic acid Moo.

Decided to dance    with danger    last night:

100 ml 95% H₂SO₄ & 62 ml MeOH were mixed together v. slowly.
Solution heated to between 90 & 120°C, while drawing a vacuum (+- 50 mm Hg) through a pipette which induced vigorous bubbling. Water in condenser ~18 °C & receiver in ice bath, ~ 10°C.
Traitorous suck back trap allowed some water into my receiver. Fortunately water was chilled.
After ~30 min intermittent operation there was an embarassingly small amount of some refractive liquid below the water layer in the receiver.  
Separated from water (~15 ml) to recover ~0.5 ml of...DMS ?

Any idea how I could check it's ID with such a measly amount ?
Probably not.

So tonight I'll revisit the scene of the crime for a longer run & see what happens.
Also might purchase an air pump & try the method according to the afore mentioned patent.
Must admit though: generating an almost odorless war gas in a positive pressure apparatus is a chilling thought.

[Antoncho]

Well.

I was glad to read your post, M_G. The method works.

As to

Any idea how I could check it's ID with such a measly amount ?

I don't think it can bee anything else than DMS - there simply can't bee any other products possibly forming in this rxn.

The low yield is probably due to unthorough mixing of the gas w/the rxn mixtr. And/or hydrolysis.


Now -
the reactions are:

1) AlkOH + H2SO4 <---> AlkHSO4 + H2O 
2) AlkHSO4 <---> (Alk)2SO4 + H2SO4

Dewatering drives the 1st reaction not the second ??


You're absolutely right, it is removal of DMS that drives the equilibrium to the right, otherwise it'd react w/H2SO4 back to HMeSO4.

Now, of course, toluene is no good for this rxn (beecause of reasons stated by Moo), but what if we take >100 C pet ether (distilled lighter fliud)?

I mean, pourquois pas? - this trick works well in case of other rxns - e.g., you can make p-MeO-phenol by methylation of hydroquinone w/DMS accompanied by mixing the rxn w/toluene.

Of course, it may work, and it may not


From the other approach - any OTC ideas on how to increase the contact surface of gas w/the liquid?


Antoncho

[Aurelius]

increasing surface area is ok, but increasing retention time also works well.  Use a deeper, more narrow vessel so the bubble's travel time (and exposure) is increased, along with faster stirring.  use fritted disks for smaller bubbles (or a finer tipped introduction device)

[Mountain_Girl]

Purchased air pump and tried the method according to the patent:
Took the previous apparatus from my attempt using vacuum, disconnected the vacuum line from the suction trap & connected an air supply line to the reaction flask instead. Assumed most of the MeOH is still unreacted in flask, i.e. didn't make up new batch.
Filled suction trap with NH₄OH soln.

Heated up to ~ 105°C while bubbling air thru.
Suction trap contents started foaming excessively. Swapped the NH₄OH soln for hot water instead (to hydrolyze any DMS that makes it past the condenser, before it gets to my lungs).
Resumed operation at 100-118°C. Condensate came over v. v. slowly. Around 113°C seemed to be optimum.

After about 1.5 hrs there was two layers in the receiver, maybe about 5 ml of water floating on about 1 ml DMS (?).
Don't know exact amounts or yield cos when I transferred to sep funnel it simply left a puddle on the table cos I didn't realise the fucking drain valve was open      !
Also got some of the stuff splashed on me. If I grow another leg out of my waist I'll know why.
[Yes I know, my clandestine chemist's license should be revoked for such incompetence but please be patient with me; I may turn out to be the WOD's equivalent of a suicide bomber]

Okay so I'm gonna try this again, probably with a fresh batch of reactants & minus the idiocy. If it doesn't seem to work well I'll give vacuum another try. If that is also not v. effective, I'll try Halfapint's SO₂/CuCl₂ synth.

Note: Patent recommends an air flow of ~ 5 cubic ft/min/gallon of mixture. In decent units, this is ~ 31 l/min/l (Oz patent IIRC, so I assume UK gallons should be used).
According to the manufacture specs of my air pump, it should deliver 4 l/min. Volume of the reaction mixture ~ 160 ml, so that gives  25 l/min/l, which I think is probably close enough.

what if we take >100 C pet ether (distilled lighter fliud)?
I think that the petr. ether may take up the DMS thereby driving the 2nd rctn, but there will still be a water build up, restricting the 1st rctn. Unless both can be removed using the Dean Stark goodie, dunno..

[Aurelius]

Just out of concern for your health, if you manage to stay alive, stop messing with this chemical. I'm glad you're making progress, but you're doing so at too great a risk to your own personal health (life).  Getting that stuff on yourself is a big NO-NO.  at the least, pick up a chemical mask capable of blocking that chemical and some chem-resist gloves and aprons.