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Sauron
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What he means by highly toxic is that DMS is a known human carcinogen and specific brain carcinogen, it causes brain tumors.
Do not mess with it
If you MUST, do so with proper protection IN A FUME HOOD.
Sic gorgeamus a los subjectatus nunc.
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peach
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Old thread, but did anyone make any more progress with it?
It may be of interest that sodium sulphate begins to loose it's water of crystallisation at just 30C, as illustrated in this patent all about cost
effectively drying Glauber's salt (sodium sulphate decahydrate) to an anhydrous state for shipping.
And concentrated sulphuric will loose water up to the point of it's azeotrope, passing it over to the receiver for the DMS to land in.
I am listing this section in red to highlight that this is theory rather than fact, regarding a potentially very
dangerous process.
If you have them under vacuum, you may shift those points and make it more favourable for water to cause problems.
2 CH3OH + H2SO4 → (CH3)2SO4 + 2 H2O
The easiest way to deal with that, more surely, would be to physically removed the hydrated sulphate once cool and before distillation, as Verdegast
suggested.
Despite me constant going on about fridge pumps, the aspirator may actually be of benefit here, as it at least provides for a constant curtain of
water over the only exit. A drying tube between it and the apparatus would help prevent vapour back streaming to the product. If using a regular pump,
I would want some form of comparable absorption trap before the exhaust made it's way out into the atmosphere.
One solution could be to use water on the low side and ammonia on the high side.
I certainly would not want to test that! However, it is in the IARC Group 2A, meaning;
| Quote: | | Substances, mixtures and exposure circumstances in this list have been classified by the IARC as Group 2A: The agent (mixture) is
probably carcinogenic to humans. |
Here's a copy of the IARC monograph on DMS for those interested.
| Quote: | Regulations and guidelines
The American Conference of Governmental Industrial Hygienists (ACGIH) (1997)
has recommended 0.52 mg/m3 as the 8-h time weighted average threshold limit value for occupational exposures to dimethyl sulfate. Values used as
standards or guidelines have ranged from 0.05 to 0.50 mg/m3 in other countries (International Labour Office, 1991). |
***
| Quote: | Studies of Cancer in Humans
As previously summarized, four cases of bronchial carcinoma were reported in men
exposed occupationally to dimethyl sulfate (IARC, 1974). Additional case reports have
since appeared: a case of pulmonary carcinoma in a man exposed for seven years to
‘small amounts’ of dimethyl sulfate but to larger amounts of bis(chloromethyl)ether and
chloromethyl methyl ether (IARC, 1987b), and a case of choroidal melanoma in a man
exposed for six years to dimethyl sulfate (IARC, 1987a). |
| Quote: | Studies of Cancer in Experimental Animals
Dimethyl sulfate has been tested for carcinogenicity in rats by inhalation, sub-
cutaneous and intravenous injection, and following prenatal exposure. It produced local
sarcomas and tumours of the nervous system (IARC, 1974). |
| Quote: | Absorption, distribution, metabolism and excretion
As previously summarized, after an intravenous injection of 75 mg/kg bw in the rat,
dimethyl sulfate was no longer detectable in blood after three minutes. No other data were available to the Working Group (IARC, 1974). Dimethyl
sulfate rapidly decom-
poses on contact with water to methanol and methyl sulfate (Figure 1) (Mathison et al.,
1995). |
| Quote: | Human carcinogenicity data
No epidemiological studies were available to the Working Group. A small number of
cases of, mainly, bronchial carcinoma has been reported. |
| Quote: | Occupational exposure
According to the 1981–83 National Occupational Exposure Survey (NOES, 1997) as
many as 10 000 workers in the United States were potentially exposed to dimethyl sulfate (see General Remarks). No information was available as to the
operations in which these exposures might have occurred. |
*** To give that some grounds for comparison, I did some digging around for Benzene, which is in the IARC Group 1 (confirmed human
carcinogen).
| Quote: | In September 2010, the Department of Labour lowered the Workplace Exposure Standard (WES) for benzene.
The old WES for benzene (as of 2002) was:
5ppm or 16mg/m3 TWA (Time Weighted Average)
The new WES for benzene (effective from September 2010) is:
1ppm or 3.19 mg/m3 TWA
2. 5ppm or 7.8 mg/m3 STEL (Short Term Exposure Limit)
What is a Workplace Exposure Standard?
There are, in fact, a number of Workplace Exposure Standards (WES), and they are all designed to give a maximum limit that a person can be exposed to,
for a particular substance, over a certain amount of time, and still remain healthy.
In the case of benzene, we use the following values:
Time Weighted Average (TWA) – this means that you could be exposed to an average of up to 1ppm (part per million) benzene over the course of an
eight-hour work day and not experience poor health effects.[1]
Short Term Exposure Limit (STEL) –2.5ppm is the highest average level of benzene you can be exposed to over a 15-minute period throughout the
working day. |
The governments own OSHA site help page for permissible exposures doesn't make mention of whether the TWA has any repetition factored in for; e.g.
whether it refers to one day or 30 years of work.
However, DOW does reference the repetition of exposure.
| Quote: | Threshold Limit Value (TLV®): Occupational exposure limit set by the American Conference of Governmental Industrial Hygienists. An airborne
concentration of a gas or particle to which most workers can be exposed on a daily basis for a working lifetime without adverse effect.¹
Time-weighted average (TWA): A method employed to calculate the exposure of workers to airborne materials, which considers the duration of exposure to
various airborne concentrations, usually during an 8-hour day.¹ |
Lots of quotes in there, but given the high carcinogen risk and lack of a wide experience base, I thought it'd be worth me posting what I've found for
anyone else perusing the graveyard.
[Edited on 21-9-2011 by peach]
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DJF90
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Sorry to bump an old thread but I've come across a complication. US patent 3024263 claims the preparation of ethyl sulfuric acid using the reaction of
ethanol with sodium bisulfate. The example refluxes an impossibly small amount of ethanol with sodium bisulfate monohydrate for 4h, but claims a
larger volume can be used if required.
I have little interest in ethyl sulfuric acid. My priority lies with finding an appropriate precursor for dimethyl sulfate preparation. To this end I
anticipated being able to replace ethanol with methanol in the cited procedure, and expected methylsulfuric acid to form. To this end, 25.06g NaHSO4
(200mmol) (pool grade, anhydrous prills) was added to 81ml of warm stirred methanol (2mol, 5x excess based on the stoichiometry 2NaHSO4 => MeOSO3H
+ Na2SO4) and the mixture was gently refluxed for 3 hours with appropriate stirring (largest magnetic stir bar that would fit in the conical flask,
set at approx 400rpm). Heating was ceased and the mixture was allowed to cool independantly for 40 minutes before application of an ice bath for a
further 30 minutes. When removed from the ice bath, a thick slush was observed. This was filtered at the pump, titurated with a little methanol and
then the filtrate was concentrated by gentle distillation of the excess methanol over an hour or so (approx 90mls collected). The yellow-tinted fluid
was left to cool before attempting a rough density measurement but on my return I was met with crystals (with a little methanol trapped within the
solidified structure (see pics).
Now, I'm not sure what's happened here. My first thought is that perhaps sodium methyl sulfate is formed in this instance. However I can't take a
melting point due to the trapped methanol, and I'd obviously like to avoid unecessarily playing around with it. I've searched extensively for some
resolve, and I've seen breif mention of "sodium methyl sulfate being formed (IIRC "Hexagon" on this site) but I cannot find a reference for that. If
it does happen to be sodium methyl sulfate, then it could be that the filtered solids could have also contained some product. I would need to find
conditions for the distillation that would yield dimethyl sulfate, something I had hoped to do in the morning (approximately 9 hours from now... So if
you can offer help quickly, that would be appreciated very much indeed.
It might be worth mentioning that just prior to concentration of the methanol solution, its pH was tested and gave an orange that changed over the
course of a minute or so to red with universal indicator paper. I believe this occurs as the paper picks up water vapour from the atmosphere.
[Edited on 31-7-2012 by DJF90]
[Edited on 31-7-2012 by DJF90]
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Nicodem
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DJF90, it's been a long time since I read upon alkyl sulfuric acids and don't really remember if methyl sufuric acid can be prepared by the reaction
analogous to the US3024263. Though, given that methyl sufuric acid can efficiently be prepared by drying the mixture of H2SO4 : MeOH (1 : 1) with
Na2SO4 (as proven by Antoncho in The Hive post #256342), I would expect that the same can be achieved by using anhydrous NaHSO4. Though one needs to
consider that a methanolic solution of H2SO4 is already prevalently MeOSO3H even before adding Na2SO4 in regard to the equilibrium (I posted a
reference on this topic somewhere), while the NaHSO4+MeOH might not achieve the same equilibrium point in the same time due to the very different
acidity.
By the way, are you sure your NaHSO4 is anhydrous? Pool quality bisulfate is usually sold as a monohydrate, at least the one I bought years ago was
such.
My only experience with this is pretty much limited. I once left a mixture of Na2S2O7 and methanol stand for a several days, filtered off the salts
and rotavaped. This gave a dense colourless liquid - no solids. I know that pyrosulfates are something else, but still, I find it unlikely that you
could obtain the sodium salt instead of the acid. Another indication that the equilibrium of MeOSO3H in NaHSO4/MeOH is rather poor, is the miserable
yield of methyl iodide obtained in a reaction designed on this hypothetical equilibrium (though there could be other reasons affecting this yield).
Are you sure that the solid is not some NaHSO4 that passed trough the filtration dissolved? This would indicate a failure of the reaction.
In case your reaction just does not want to work, I would suggest a modification that would modify the reaction system to be as similar to the
NaHSO4+EtOH reaction as possible. The first such possibility is to reduce the solubility of the bisulfate, for example, by adding toluene as an inert
solvent to the methanol. I would use a 4 : 1 or 3 : 1 ratio of MeOH vs. PhMe. Also, let the reaction mixture stand for a day or two before you filter.
PS: In case you are not aware of US1411215, the AlkylOSO3H can efficiently be used directly in the preparation of dialkyl sulfates if anh. Na2SO4 is
used as a buffer during the thermolysis. Unfortunately again, the patent only gives diethyl sulfate as the example.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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DJF90
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Thanks for taking the time to write me a reply Nicodem. I gave up trying to work out what happened (I couldnt get it dry enough to take a melting
point although it was like a fine slurry on the hotplate at 150*C) and instead I've just started the addition of sulfuric acid to methanol as per
Painkilla's preparation, which references US3047604 and US1411215. I've also taken time to dry my sodium sulfate quickly with a heat gun (I bought
anhydrous on ebay a while back but it was packed in a ziplock bag) and ground it finely whilst hot (it was mostly fine anyway so it didnt take long).
I should finish the preparation of the methylsulfuric acid this evening, and filter it into the distillation flask (and stopper it) ready for the big
distillation tomorrow. I'm running the prep on half the scale of Painkilla, using 1.05 mol methanol and 1 mol sulfuric acid, So I guess theoretical
yield is half a mole; 63g (approx 47ml). Assuming a 40% yield like Painkilla, I'll be staring nervously at approx 20ml by tomorrow evening.
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Draco_440
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Why not follow the method posted here
http://www.sciencemadness.org/talk/viewthread.php?tid=5495
Stop after gas evolution and drip in methanol, reflux then distill
Na2S2O7+2MeOH ---->Na2S04 +(Me)2SO4+H2O
I remember reading a patent for it, I'll see if I can dig it up
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SM2
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1) Take out a good insurance policy on your self.
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AndersHoveland
Hazard to Other Members, due to repeated speculation and posting of untested highly dangerous procedures!
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Quote: Originally posted by Haggis  | | Dimethyl sulfate...hmm. It's rapidly absorbed into the skin. Once inside the skin, the hydrolysis products are methanol and sulfuric acid. Sounds
like a wonderful way to die. You go blind as the methanol is attacking your optic nerve and liver, while the sulfuric acid is scarring your veins,
causing inflammation and possibly internal bleeding. |
Actually, the reason it is so toxic is because it is an alkylating agent. Cellular DNA gets methylated.
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