Melgar
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Diethyl sulfate synthesis that's too good to be true?
I've seen a lot of interest in various ethyl esters of sulfuric acid posted around, and they all seemed really, really complicated. Now, if I'm not
mistaken, diethyl sulfate is nowhere near as toxic as its dimethyl counterpart, even though it's far from benign. However, the difficulty of
acquiring pure anhydrous ethyl alcohol without any methanol in it, might complicate things on that front. And starting with ethanol might not even be
a good idea, since it can be dehydrated into ethylene by a strong dehydrating agent, which could easily lead to polymerized crap, as in the case of
P2O5 + ethanol.
What about diethyl ether though? It's easily obtained from starting fluid, free of water, methanol, ethanol, and ethylene. And the stoichiometry of
its reaction with SO3 works out, not to mention it'd be analogous to the industrial reaction of SO3 and dimethyl ether for making dimethyl sulfate.
SO3 is extremely reactive, but diethyl ether is famously inert. Granted, this seems like a fire hazard of the highest order, but with proper
precautions and only a few mL of reagents, the risks would be minimal.
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unionised
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I suspect that the reaction of SO3 with ether is... enthusiastic.
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JJay
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Also, if you have an easier time getting diethyl ether than ethanol, I want the names of your suppliers.
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Melgar
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I'm not saying diethyl ether is easier to obtain than ethanol, however it IS easier to obtain diethyl ether that's free of water and methanol than it
is to obtain ethanol that's free of water and methanol. I've always just gotten premium starting fluid for two and a half bucks for a 10-ounce can at
Wally World, and that's roughly a third ether. The rest is heptane and high-boiling motor oil stuff, and I usually keep the heptane because it can be
useful. But if someone wanted to moderate the reaction, starting fluid could be distilled without a fractionating column, just to remove the motor
oil, then SO3 could be added to that under strict anaerobic conditions.
edit: Assuming CO2 is inert under these conditions, dry ice could be added to the heptane/ether mix before the SO3, which would both lower the
temperature and provide a blanketing, inert atmosphere to exclude oxygen from the reaction. It would also greatly reduce any potential for an ether
fire.
[Edited on 11/12/17 by Melgar]
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clearly_not_atara
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Isn't there a route where ethylsulfuric acid is heated with some kind of base and it disproportionates to Et2SO4 and SO4(2-)? Sounds a lot nicer than
anything involving (anhydrous?!) SO3...
[Edited on 04-20-1969 by clearly_not_atara]
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Melgar
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Could be. I was mostly thinking that the need to exclude water from the mix would be because of the enormous heat that'd be released from its
reaction with SO3. But if H2SO4 was a component of the SO3, that wouldn't be an issue. I'm assuming you meant H2SO4-free when you said "anhydrous"
as a descriptor for SO3.
SO3 isn't one of the easiest things to obtain, but neither is it one of the hardest, especially if it's used immediately. Thermal decomposition of
iron sulfate will produce it, and apparently even aluminum sulfate can be used, at 900-1000 C or so. Sodium bisulfate can produce it, of course,
although the water that's also produced could be a deal-breaker, and I don't have any experience with that reaction myself. It'd be less convenient
to use as a product of the contact process due to the presence of oxygen, but only slightly less so, and I doubt many people here that obtain SO3 use
the contact process to obtain it.
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JJay
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I suspect that anhydrous potassium ethyl sulfate will emit diethyl sulfate if heated.
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macckone
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diethyl sulfate is an intermediate in the production of ethyl ether or
ethylene from ethyl alcohol and sulfuric acid. And yes in any reaction
forming diethyl sulfate there is 'gunk' formed. sodium ethyl sulfate will
become diethyl sulfate and sodium sulfate. Heating then yields ethyl
ether with little 'gunk' and little ethylene formed. This is useful to use
sodium bisulfate with ethanol to make ethyl ether. Vodka is pretty pure
ethyl alcohol with water. Removing the water is covered in other posts.
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SWIM
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1 volume ethanol + 2 volumes sulfuric acid.
Distill under vacuum.
You'll get 2 layers in the receiver flask.
It works with aspirator vacuum.
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JJay
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I suspect potassium ethyl sulfate works better than sodium ethyl sulfate unless you can somehow obtain sodium ethyl sulfate in its anhydrous form.
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