Some Stuff

So, all of the isomers of C4H11O are in NMRShiftDB  and here are all the experimental and predicted carbon spectra: It's not obvious from this picture, but not all of the predicted spectra are unique matches for their experimental partners. In other words, you could not pick out the right molecule by comparing the predicted and experimental spectra. The situation is more difficult still for larger isomer spaces, where the predicted spectra may be exactly the same for sub-sets of the isomers. There are still many with unique predictions, but the rest follow a sort of power-law distribution of spectral-equivalent sets. EDIT: As per a suggestion by egon, here is a table of top hits (a yellow square indicates the top match):

With a slight change of data, and a change to the bond order settings, now 2,737 out of 5,739 match exactly. 1,114 of the rest get the right one in the top 10. That still leaves almost 2,000 - but some of these are clearly poor experimental data.

I made a tiny minimal tool for me too look at the results of spectra matching. Re-inveting several wheels, no doubt, but it does use CDK trunk rendering...sortof.