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DJF90
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Methyl iodide is actually only a suspected carcinogen (at least last time I looked), whereas dimethyl sulfate IS a carcinogen. Just a little something
to think about... I agree about the volatility issues involved though.
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mr.crow
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Like in that book by Gergel posted in the library. He was severely poisoned by MeI but apparently lived to tell the tale.
What defines a carcinogen? Ability to cause mutations?
Double, double toil and trouble; Fire burn, and caldron bubble
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smuv
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No. Thats just a mutagen. Lots of things that are not carcinogenic are mutagenic.
Carcinogen is ability to cause cancer. If it is proven to cause cancer in animals (usually rodents), and is reasonably anticipated to cause cancer in
humans then the compound is labeled as a suspected carcinogen. If through exposure studies (generally sampled from workers who use the chemical)
there is found to be a statistically significant increase in cancer (that is shown independent of other agents) then the compound is labeled a
carcinogen.
It is often difficult to prove something a carcinogen in humans because you can't exactly put someone in a cage and expose them to ungodly quantities
of certain chemicals, so it is hard to establish that the causes of cancer in the group you are researching are not caused by other factors. This is
why so many compounds are labeled as "suspected carcinogens".
[Edited on 2-15-2011 by smuv]
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Fleaker
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I had one bad experience making dimethyl sulfate. I made it several different ways and experimented quite a bit with it. In a good hood no less, but I
still do not like it and shall not ever mess with it again. Let me give you some advice all, give it ample time to hydrolyze and be not impatient! For
if you take your reaction out of the fume hood under the assumption that it is all gone, be very sure!
mr.crow, I was about to mention that it never killed Mr. Gergel. But I think he mentions extreme insomnia only curable with phenobarbital following
that exposure. It works a treat for starting a Grignard formation.
Neither flask nor beaker.
"Kid, you don't even know just what you don't know. "
--The Dark Lord Sauron
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Nicodem
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Crosslinking threads: Trimethylsulfonium bromide and its use for the methylation of phenols (in Prepublication section)
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Nicodem
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Quote: Originally posted by Nicodem  | | Paddywhacker, DMFDMA methylates only exceptionally and it does so trough the Me2N<sup>+</sup>=CH-OMe cation which forms after protonation
and MeOH elimination. This however does not form in the basic media required for the deprotonation of most phenols (their pKa is generally from 9 to
10). Therefore DMFDMA does methylate carboxylic acids and sometimes it even leads to some methylation of very acidic methylene groups as a side
reaction (instead of cleanly introducing the =CH-NMe2 group). But in my opinion with phenols it could utmost just O-formylate them unless under some
unusual conditions or using very acidic phenols as substrates (like nitrophenols). |
Nicodem to Nicodem: You are so full of shit! DMF-DMA does methylate all kinds of phenols. They need not to be particularly acidic.
Nicodem to Nicodem: Really? Please provide a reference!
Nicodem to Nicodem: If you would have taken 5 minutes to do a literature search, instead of speculating, you would have found that this has been known
for over 30 years (see Tetrahedron, 35, 1675-1735). And just a few days ago, a more detailed study was published (see Tetrahedron Letters, 52, 2776-2779).
Nicodem to Nicodem: Interesting. So I was wrong again. Anyway, you should not trust anybody who claims anything without a reference, you dumbass!
…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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indiangold
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one more rather uncommon methylating agent is phenyl trimethyl ammonium chloride. It is especially useful to methylate phenolic groups in compounds
that also contain 3° amine functions. it is used is for conversion of morphine to codeine.
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jon
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| Quote: |
It is often difficult to prove something a carcinogen in humans because you can't exactly put someone in a cage and expose them to ungodly quantities
of certain chemicals, so it is hard to establish that the causes of cancer in the group you are researching are not caused by other factors. This is
why so many compounds are labeled as "suspected carcinogens".
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actually you can, big industry dumps chemicals in impoverished neighborhoods all the time.
the people can't leave because they don't have the resourses.
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byko3y
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Wow-wow-wow, hold on a second
| Quote: Originally posted by not_important | | Methyl tosalate - the methyl ester of p-toluenesulfonic acid is another methylating agent. Low vapour pressure, the resulting alkali salt of the acid
can be converted to the chloride (for making the Me ester) using the S-Br2 method |
So this man is telling that you can actually convert sodium tosylate to tosyl chloride with something except phosphorus chlorides and thionyl
chloride?
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clearly_not_atara
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Well, he's only half wrong. It's generally agreed that S2Br2 converts sulfonic acids to their anhydrides by an unknown mechanism; presumably the
disulfonyloxydisulfide intermediate is too unstable to isolate. However of course other reagents exist; cyanuric halides come to mind, as does
antimony pentachloride.
What's more interesting to me is I'm still pretty sure the pyrosulfate route will work with methanesulfonic acid (possibly toluenesulfonic acid), even
though it didn't work with acetic acid. Sulfonic acids do not undergo aldol condensations nor are they easily oxidized, alleviating two possible side
reactions, and Ms2O is significantly more volatile (bp 30º lower) than MsOH.
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