[Fry]

Im supposed to analyse an 1H-NMR of trans-9-(2-phenylethenyl)anthracene

I synthesized it from 9-anthraldehyde and benzyltriphenylphosphonium chloride.. Chloroform was used as the solvent in the reaction.

Anyway, the spectra given to me shows 7 different integration values of various peaks.. there are a few other peaks without these integrals, what is the significance of this? Are they minor impurities? How can the signals be so strong if they are minor impurities? Most of the peaks are grouped in the 6.8-8.3 ppm range which makes sense for all the protons around the conjugated pi systems.. there are two peaks upfield, one at 1.5 and the other at 0.9.. am I correct in thinking that one of these must be due to the chloroform? There is also another peak, a singlet, in the jumble of peaks up by 6.8 that doesnt have an integral value

Also, is it normal to have different ppms stated for different peaks that are under the same integral?

Sorry.. Im very new to spectroscopy, Im reading "an introduction to spectroscopy" by pavia/lampman/kriz but its not of much *delete me*

Im used to having tailored spectra problems given to me, ones with perfect peaks and everything.

[macman104]

Hey Fry,

So, did you obtain the NMR spectra yourself, or do you just submit it, and then some tech runs it, and returns it to you?  If possible, you might want to get integration values for those other peaks.

Chloroform (or usually they use the deuterated form CDCl₃), has a peak at ~7.26 ppm (all those Cl's push it downfield).  That sounds like that singlet in the jumble of peaks.  Your compound should not have any peaks in the range down by 1.5 or 0.9. 

0.9 is a pretty typical value for a alkyl CH₃ peak.  I'm reading over the synthesis, assuming you follow the same one here.  Did you dry your compound before running the NMR, because residual 1-propanol would show peaks at 1.5 and 0.9 ¹H NMR of 1-propanol.

For your other questions...

It is normal to have ppm assignments for each peak, even if they are all under the same integral.  If the program is picking the peaks, it usually doesn't care what integral they're under, it just labels the peaks.  You just know that they are all for the same hydrogen, just split.

Also, I hear ya on only being only used tailored spectra.  Actual lab run spectra aren't so pretty usually.  I'll write more later, but gotta go.

If you can, scan your spectra, and I'd be happy to help you interpret it.