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Old May 24th 2017, 10:41 AM   #1
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Urgent! Unexpected NMR signal

I synthesized aspirin in the lab and ran an H-NMR test. My solvent was CDCl3.
In the spectrum a doublet signal appears at 4.77,4.82 ppm. I have tried thinking about any byproducts that might have caused this signal and searched the web with countless search terms trying to find a reasonable answer to this but nothing of use came up.
At one point I thought this might be due to residue water however the signal for water in my solvent should appear around 1.6 ppm and is a singlet.
I have found a resource claiming that at 4.5-6.5 ppm we are dealing with c=c double bonds, however, none of the byproducts I know of include any such bonds (except of course on the ph group which appears at a much higher ppm).
Thanks so much to any helpers!
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