legionbob (Newbee)
08-28-01 07:38
No 208007
      OTC preperation of Dimethyl sulfate?  Bookmark   

    Well, Bob's made his little stash of personal use MDMA, and It Is Good.  Time to try something new, say, tryptamines!   I'm intrigued by the methylation of tryptamine via dimethylsulfate (with a carbonate as acid scavenger.)   Problem is...where to get DMSulfate?   The handy Merck says 'distilled from oleum and methanol', with 'oleum' being a solution of SO3 in H2SO4.  (fuming sulfuric acid.)   From what I've gleaned from the Merck, it seems possible that simply H2SO4 + MeOH might form the desired product, but it easily hydrolizes back to to starting reagents in the presence of water.
    So...question is, is there a sane way to dehydrate sulfuric acid (to get a decent ammount of free SO3 in it) in the comfort of my home, or could common 90-odd% sulfuric acid work if you had something to scavenge the moisture (say dry MgSO4 or perhaps ceramic molecular sieves?)
    Or is there a better OTC way entirely?  (I refuse to mail-order so much as a coffee mug from chemical supply shops.  They may not want to bother anybody, but why leave any sort of paper trail just in case?)   Since one can get tryptamine so easily it's driving me nuts not to have an OTC way to alkylate it.

Legion Bob
"We're Everywhere!"
(Chief Bee)
08-28-01 08:28
No 208023
      Re: OTC preperation of Dimethyl sulfate?  Bookmark   

The only thing I know besides SO3 that would dehydrate 96% sulfuric acid is phosphorous pentoxide (P2O5), which reacts with the water to form phosphoric acid.

Dehydrating 96% H2SO4 with molecular sieves, silica gel, MgSO4 or one of the other usual drying agents would be as fruitless as trying to run a vacuum pump on a penlight battery.
08-28-01 13:02
No 208073
      Re: OTC preperation of Dimethyl sulfate?  Bookmark   

SWIUTFSE dreamed about the possibility to obtain SO3 by mixing agricultural super triple phosphate
which is P2O5 and CaHPO4 (calcium phosphate) about 46% P  with concentrated H2SO4 into a thick

Gently heating this mixure and subliming the vapors (SO3) in a nitrogen atmosphere.

Or better passing vapors through H2SO4 to obtain fuming sulfuric acid.

No original though here just read it somewhere. 

always appreciate your time and consideration
(Ubiquitous Precursor Medal Winner)
08-29-01 09:34
No 208329
      Re: OTC preperation of Dimethyl sulfate?  Bookmark   

Dimethyl sulfate can bee made from sulfuric acid and methanol, if and only if you have a vacuum source. In fact, I'm vacuum distilling some right now. Methanol 100 ml was placed in a 1000 ml beaker set in an ice bath. 370 ml sulfuric acid, a large excess, was added dropwise with swirling. (This acid is dirty, black in color, having been salvaged by filtering through a glass filter, from previous runs; but I would recommend the use of 320 ml even if the acid were clean, to reduce losses due to the formation of dimethyl ether.) Dimethyl sulfate is distilled under reduced pressure from this methanol/acid mix.

At its boiling point of 188o it decomposes, so it cannot be distilled at atmospheric pressure. Diethyl sulfate can be obtained in exactly this same way, but not so the higher alcohols. When an excess of concentrated sulfuric acid is added cold to ethyl or methyl alcohol, the alkyl hydrogen sulfate is formed. Under reduced pressure distillation, however, the diethyl or dimethyl sulfate distills over.

Edit: Arrgh. While I was in here posting this I had a boil-over, which got through into the receiver. I blame it on the dirty acid, bumpy boiling, set too hot. Back to square one.

turning science fact into <<science fiction>>
(Hive Bee)
08-29-01 10:30
No 208341
      Re: OTC preperation of Dimethyl sulfate?  Bookmark   

Jesus, Halfapint comes through again!! Truly the "Ubiquitous Precursor Medal Winner". I love the title, just seems so fitting and right. Glad to know there are somethings you can depend on in this crazy world. tongue
(Chief Bee)
08-29-01 11:10
No 208351
      Re: OTC preperation of Dimethyl sulfate?  Bookmark   

Halfapint: Do you have a reference for this reaction somewhere? What is the general yield?
(Ubiquitous Precursor Medal Winner)
08-29-01 14:42
No 208398
      Re: OTC preperation of Dimethyl sulfate?  Bookmark   

Effectively, I am without technical library access. I get old texts, and it is from one such this preparation comes. Principles of Organic Chemistry, T.A. Geissman, W.H. Freeman 1962. Geissman devotes pages 126-130 to eight equilibrium reactions occuring in sulfuric acid mixed with ethanol. I give his section on diethyl sulfate:

At low temperatures, and with excess sulfuric acid, the chief constituent of the mixture is ethyl hydrogen sulfate, EtOSO3H. If the mixture is now heated under reduced pressure to a temperature at which diethyl sulfate, EtOSO2OEt, distils, the removal of the diethyl sulfate shifts the equilibrium EtOSO3H + EtOSO3- <--> EtOSO2OEt + HSO4- to the right, with the result that the overall equation
        2EtOH + H2SO4 --> Et2SO4 + 2H2O
represents the result of the process as a preparative operation.

Then, after discussions of diethyl ether and of ethylene, Geissman presents a section called The Formation of Alkyl Sulfates:

Although a great deal of attention has been paid to the reaction of ethanol and sulfuric acid, this has been done primarily because that reaction is a good example of some important fundamental principles. Comparable reactions are shown by other alcohols. For example, dialkyl sulfates other than diethyl sulfate can be prepared in a similar manner. Dimethyl sulfate, (CH3)2SO4, is made by the reaction of methanol and sulfuric acid. Higher dialkyl sulfates (such as di-n-propyl sulfate) become increasingly difficult to prepare in good yield by this method, however, because as the boiling point of the desired dialkyl sulfate becomes higher with increasing molecular weight, the higher temperature required for their removal by distillation allows the side reaction of olefin formation to assume greater prominence, and, eventually, to be the principal reaction.

This, and a brief supporting comment in another text, led me to try it. As far as yields, well, ahem. Half-a-Pint's lab technique is a bit rough around the edges sometimes. Geissman implies fair yields are achievable with ethanol and methanol; but Half-a-Pint has a bunch of syringaldehyde to methylate, and needed some DMS PDQ, so decided to bull ahead with whatever works, and work on the technique and improving the yields later. 2 runs averaged 15%, not good, but I know it's sloppy to use recycled acid. Other details of trying to work out a prep also got in the way: the first run did not have enough excess acid, and lots of dimethyl ether went bye-bye before I noticed nothing much was condensing. Another run got lots of liquid (presumably water) in the KOH trap I was using to protect my vac from sulfuric fumes, had to be stopped before the pump aspirated caustic solution, and so forth, you know. Tell you what, I'll make a clean run and write it up in Chemistry discourse; I've already made ethyl sulfate by this route, so I'll try a clean run on that too.

turning science fact into <<science fiction>>
(Distinctive Doe)
09-23-01 15:28
No 216467
      Re: OTC preperation of Dimethyl sulfate?  Bookmark   

More details on otc diethyl sulfate are here
Post 216461 (foxy2: "Ethyl hydrogen sulfate", Chemistry Discourse)

Do Your Part To Win The War
(Master Searcher)
09-23-01 21:17
No 216526
      Re: OTC preperation of Dimethyl sulfate?  Bookmark   

See US patent 1317648 Process for the Production of Dimethyl Sulfate.  Uses MeOH, SO2 and Cl2.

I'll add some more as I find them.
US patent 1427215 uses drying agents such as Na2SO4, CuSO4 or P2O5 with SO3 for fuming sulfuric acid for making dialkyl sulfates.
1506228 from pyrosulfates or chlorosulfonates
1641005 sulfuryl chloride