Sciencemadness Discussion Board

Dimethyl Sulfate

Blind Angel - 5-11-2003 at 21:55

Is it findable OTC?
Synthetisable? I found a way to synthetise Diethyl Sulfate on Rhodium can i apply it using methanol instead of ethanol?

Marvin - 5-11-2003 at 23:26

Being a very potent methylating agent I would expect this to be a tad carcinogenic to be found OTC. Very nasty stuff I hear healthwise, I'd stick to non volatile alkali sulphate salts if it were me.

Blind Angel - 6-11-2003 at 04:39

Yeah, i heard it was nasty too. It's used in ether's synthesis. The Organicum refer a lot to it, and they are pretty generous on the warning...

vulture - 6-11-2003 at 10:55

This stuff goes through your skin like a hot knife through butter. Very toxic. Nasty shit.

DDTea - 6-11-2003 at 12:20

Dimethyl Sulfate is a very nasty chemical to have an accident with... Not only does it cause severe skin damage from Sulfuric Acid released on contact with moisture (and often BELOW the epidermis), but the methanol released also poisons the kidneys. But, all chemicals have their risks, and with due care Dimethyl Sulfate is a very useful reagent. It is a much more potent methylating agent than Methyl Iodide, for example.

Synthesis is very very easy for Dimethyl Sulfate- add Methanol to concentrated, fuming Sulfuric Acid. It should be much easier than preparing ethers, since the goal here is not dehydration, but esterification.. As such, it is not as crucial to remove the water that is formed (though it seems like it would affect yields).

2 CH3OH + H2SO4 -- > (CH3)2SO4 + 2 H2O

Here is an excerpt from The War Gasses about this method:
Quote:
Guyot and Simon, employing oleum containing 60% SO3 in the last method have obtained a very high yield of dimethyl sulphate (about 90%).


Alternately, there is the industrial synthesis which uses Sulfuryl Chloride and Methanol...

Cl2SO2 + CH3OH -- > (CH3)2SO4 + 2 HCl .

Blind Angel - 6-11-2003 at 15:01

Wouldn't CH3OH + H2SO4 yield CH3OCH3 (Dimethyl Ether), this is how diethyl ether is prepared, there mus not be a big difference between the two no?

DDTea - 6-11-2003 at 16:32

Indeed, the reaction to form Dimethyl Sulfate is similar to the reaction to form Dimethyl Ether... In fact, Dimethyl Sulfate is the intermediate in the formation of Dimethyl Ether. In that reaction though, Sulfuric Acid serves as a catalyst as opposed to a true reactant...

I don't know why it wouldn't form Dimethyl Ether and would just stop at Dimethyl Sulfate. The reaction to produce the Ether does require heating though... so perhaps it involves decomposition of Dimethyl/ethyl Sulfate to form the ether, which is then condensated?

Blind Angel - 6-11-2003 at 20:42

H2SO4 --H2O--> H+ + HSO4-
HSO4- --heat--> H+ + SO4--
true?

So:
H2SO4 + CH3OH --H2O--> H2O + HSO4CH3
(monomethyl sulfuric acid?)

HSO4CH3 + CH3OH --H2O + Heat?--> (CH3)2SO4 + H2O --Decompose--> H2SO4 + CH3OCH3

I think that Rhodium synthesis using Sodium Sulfate would work better and be easier to control, no?

Blind Angel - 15-11-2003 at 13:48

I tried today to synth some

I added a 1:1 ratio of methanol to sulfuric acid (non fuming sorry, don't even know the conc., it was silver cleaner Sulfuric Acid and my father didn't want me to boil it inside) in the snow since DMS hydrolyse at temp over 16°C.

My calc where wrong, the ration shouldn't have been 1:1 i know but anyway, no reaction occured at all, not even a little fizzing. I'll continue to let freeze outside the mixture, if ice appears then it will be good sign...

unionised - 16-11-2003 at 04:09

If ice apears it will show that there is a lot of water present. Since DMS reacts quite rapidly with water it will prove you don't have any DMS. I never understand the idea that, for example, "dms hydrolyses above 16C". Do people think it has a little thermometer? In reallity DMS hydrolyses; it is slower in the cold and faster when it's warm. The only way it could suddenly stop hydrolysing would be when the reaction mixture freezes. That won't happen until you are below the freezing point of the DMS at -27C.
I'm also puzzled by the synthesis given on Rhodium. It says you collect the product (a mixture of DES and ethanol) in a sep funnel. Those 2 compounds mix. You might be able to separate the DES from the water that is formed as a by product.

[Edited on 16-11-2003 by unionised]

Blind Angel - 16-11-2003 at 10:38

This was my fear :(
So i let the reaction sit overnight in the cold, Yellowish ice appeared, i fear that it's mosly water and maybe Dimethyl Ether :(

unionised - 16-11-2003 at 13:31

Dimethyl ether is a gas (Bpt about -24C). Are you sure you should be working with anything as nasty as dimethyl sulphate?

Blind Angel - 16-11-2003 at 14:52

sorry, wasn't able to acceed my Merck when i posted this. Anyway for your info, no gaz evolved from the reaction, and i'm outside in the snow @-10°C and i'm wearing a gaz mask

[BTW] Properties: Colorless oily liq. Poisonous. Corrosive. bp approximately188degrees (with dec) ; bp 15 76degrees . mp minus27degrees . d 4 20 1.3322 . n D 20 1.3874 . Flash pt 182degreesF (83degreesC). Soly in water 2.8 g/100 ml at 18degrees. Hydrolysis is rapid at or above this temp. Vapor density 4.35. Sol in ether, dioxane, acetone, aromatic hydrocarbons. Sparingly sol in carbon disulfide, aliphatic hydrocarbons. LD 50 orally in rats: 440 mg/kg (Smyth)

[Edited on 16-11-2003 by Blind Angel]

best synth..

SciGuy - 19-11-2003 at 20:20

Rhodiums synth performs fine but there are a few things to work out. Mainly the concentration of methanol to sulfuric. The Sodium Sulfate indicated in the writeup is strictly to absorb moisture and drive the reaction to the right as it is reversable. The wording in it is also confusing as at first read it seems like a flash distillation. This is not necessary, and neither is the sodium sulfate. Anhydrous Magnesium sulfate (dried epsom salts) works fine.. The preferred ratio of H2SO4/MeOH is: ~3:1. It must be boiled (heated) slowly with vacuum as the compond is notoriously nasty as a vapor.. it also decomposes at its atmospheric boiling point. Use a sodium hydroxide trap (breaks the compound down to harmless substances) before any vapors reach your pump as the DMS fumes will wreak havoc on your insides quite possibly including your DNA/RNA. <--no joke. Remember also skin absorbs this substance better than a sponge and you dont want this stuff pulsing through your body. Its vapor density is rather low so there is minimal risk of inhalation once cool and in storage. Finally, remember to wash the substance with distilled water and sodium bicarbonate because you will most likely get a 2-part mixture of methanol and DMS once distilled.

DDTea - 20-11-2003 at 12:08

Wouldn't the Sodium Bicarbonate and the water react with the DMS and break it down?