Author Topic: Ethyl hydrogen sulfate  (Read 18016 times)

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  • Guest
Small DMS synth test
« Reply #40 on: April 08, 2003, 09:05:00 AM »
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.


  • Guest
« Reply #41 on: April 10, 2003, 04:38:00 PM »

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?



  • Guest
Surface area-
« Reply #42 on: April 10, 2003, 08:54:00 PM »
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)


  • Guest
Update: DMS under +ve pressure
« Reply #43 on: April 11, 2003, 11:00:00 AM »
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..


  • Guest
« Reply #44 on: April 12, 2003, 11:08:00 PM »
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.