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Topic: peak at 0 ppm H NMR  (Read 13848 times)

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Offline trishasales714

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peak at 0 ppm H NMR
« on: March 25, 2017, 11:20:59 PM »
What is this? I sometimes have this on my spectra.
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Offline Dan

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Re: peak at 0 ppm H NMR
« Reply #1 on: March 26, 2017, 05:30:45 AM »
Probably tetramethylsilane, which is sometimes added as an internal standard at 0 ppm
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Offline wildfyr

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Re: peak at 0 ppm H NMR
« Reply #2 on: March 26, 2017, 01:32:08 PM »
If its intermittent could be vacuum grease (an oligosiloxane I believe). It shows up at .05-0 ppm or so. If its consistent then Dan is probably right (but its usually only in CDCl3).

If its grease, more care when decanting reactions, or flashing through a plug of silica with hexane, discarding the hexane and pushing your product with a more polar solvent can remove it. Or distillation.
« Last Edit: March 26, 2017, 02:20:02 PM by wildfyr »
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Offline Irlanur

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Re: peak at 0 ppm H NMR
« Reply #3 on: March 27, 2017, 04:29:23 AM »
Quote
Probably tetramethylsilane, which is sometimes added as an internal standard at 0 ppm

It would be pretty funny if he wasn't aware of that...;)
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