chornedsnorkack
National Hazard
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Registered: 16-2-2012
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Fluoromethylsulphonic derivatives
The group CH3SO2- is mesylic group, symbol Ms. It is a useful radical. MsOH does have thermal stability limitations - it is said
to decompose slowly from 225 Celsius and rapidly from 250 Celsius as
CH3SO2OH=CH3OH+SO2
The group CF3SO2- is triflic group, symbol Tf. It also is a useful radical. TfOH is more stable than MsOH, being stable to 350
Celsius while it boils at 162 Celsius.
Are there any acids in the forms of CH2FSO2OH and CHF2SO2OH? How robust are they for handling? How useful
are they to tune the properties of their derivatives?
Now, dimethylsulphone is a fairly stable and inert substance. It is resistant to base... CH3SO2CH3 has pKa about 31.
Realize that when you express it without symmetry, dimethylsulphone is CH3Ms!
What are the pKa and other properties of CH3Tf?
Or how about CH2Ms2? CH2Tf2?
HCTf3, despite having the hydrogen on C, is said to be a stronger acid than HOTf itself. How about HCMs3?
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Dr.Bob
International Hazard
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Registered: 26-1-2011
Location: USA - NC
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Triflic acid may be mor heat stable, but it is a much stonger acid, and quite reactive. The anhydride and acid chloride of trific is much more
reactive than mesyl as well. One useful bit of trivia, is that mesyl chloride often has a top layer of mesyl acid, which can be removed via a sep
funnel. This is a good way to clean old mesyl chloride, as it hydrolyzes readily. And triflic anhydride is quite unstable to storage for long,
based on my experience.
I do think I have seen some difluoro mesyl compounds, but pretty rare and expensive. I belive that these are not very stable and can rearrange due
to the lose of HF to form weird radical like things, but I don't have the papers here to look back at. Even more fun was the triflic acid fluoride,
which a coworker once had to use, that was exciting, it etched much of the glassware used badly.
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