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Logic Puzzle #16: Can you spot the Impurity(s)? … Solution

June 1, 2011

If an elucidator is too successful differentiate an impurity signal from a signal belonging to a compound-of-interest, then the following may be useful: foreknowledge of the prep work, experience with similar compounds and impurities, variations within the spectral data, trial-and-error, etc.

From the 1H NMR spectrum, the integral of the 1H signal at 2.52 ppm is approximately a third less than the other integrals. This slight difference is an indication that this particular signal may be an impurity.

The 1H -13C HSQC spectrum shows all the 1H signals as protonated carbons. The integrals from the 1H NMR indicate that most of the protonated carbons are methine carbons (CH).

When attempting to solve for this unknown compound, it may be best to not use any information correlated to the 1H signal at 2.52 ppm and see what potential candidates arise without it.


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