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A couple of basic questions. So in this spectrum, there seem to be two peaks at 2.38-2.347, but this signal should be a singlet and correspond to the methyl group. So does this mean anything? Another question is, there is an integration of 1.02 at around 2.00-1.50, but there is no peak. Could this mean impurities, or do I just ignore?

NMR

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    $\begingroup$ I rolled back the edit because the question (and the answer) makes little sense without being able to see the spectrum. It would be nice to specify what instrument was used (e.g. 300 MHz) and what the solvent was, if any. $\endgroup$
    – Karsten
    Aug 22, 2023 at 16:05

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It's impossible to see from your spectrum whether there's one or two peaks. You need to zoom in.

But I get the sense you're referring to the 'peaks' at the top (i.e. the numbers) which are chosen by automatic peak picking, I wouldn't worry about them: the peak picking algorithms can often be over-sensitive and report many 'peaks' that aren't really peaks.

As for the broad peak at around 1.6 ppm, that's probably just water, nothing to be concerned about. You can find a very thorough list of common impurities and their NMR chemical shifts at: Organometallics 2010, 29 (9), 2176–2179. (By the way, just because the peak picking algorithm didn't tell you there was a peak there, doesn't mean that there isn't one. Look at the spectrum, not the numbers on top; there are certainly peaks in that region.)

There are impurities in your product, for sure — you can see extra peaks at the baseline — but nothing too significant.

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  • $\begingroup$ The only other thing it's perhaps worth mentioning is that while predicted peak locations from a structure given by e.g. chemdraw are usually "about right", they are decidedly not completely right, particularly where labile protons are involved... $\endgroup$
    – Landak
    Aug 23, 2023 at 8:49

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