[doelling]

I've attached a nmr spectrum from my orgo lab this week (substance is 4'-phenylacetanilide) and I can not figure out where to begin assigning peaks. Based on the structure, there should be 7 seperate signals, but only 4 show up with integration values. The CH3 group is the one around 2.2 ppm, I think. And I think the NH group is the one at 7.25 ppm. Other than that, I'm lost. Any help on where to start would be awesome!

Spectrum: http://i.imgur.com/0Y2LYQl.jpg

P.S. Forgive my elementary school-level drawing skills

[Babcock_Hall]

I would start by looking up the chemical shift of CHCl₃, which is always present, though in small quantities, when one uses CDCl₃ as the solvent.  I noticed that you have an integral of 7 for one signal.  What do you think of that?

[doelling]

CDCl3 is the one at 1.745 ppm, correct? The 7 integration would have something to do with the phenyl groups, I'm just not sure how they're split up

[doelling]

Maybe the 7 is the 5 on the "left" ring and the 2 left Hs on the other ring. The only reason that could make sense is if the 2 right Hs were deshieled slightly by the nitrogen

[kriggy]

First of all I suggest googling a table of 1H chemical shifts, it can help a lot.
Second, I dont know how much NMR spectroscopy did you cover at lectures etc, but as you can see, the real spectrum can be not as nice as the one shown in your book - the signals are overlaping, you can see interactions over more than 3 bonds, especialy in aromatic area etc..
Sometimes, you also cant see a signal of acidic proton, Sometimes, the integration values doesnt give you integer.


CDCl₃ is not at 1,75. Try to google solvet shift chart

[doelling]

Whoops, that's water in CDCl3. The solvent peak is the one at 7.257

[Babcock_Hall]

Maybe the 7 is the 5 on the "left" ring and the 2 left Hs on the other ring. The only reason that could make sense is if the 2 right Hs were deshieled slightly by the nitrogen

Aromatic rings do not always follow the generalization that being close to an electronegative atom forces the hydrogens to become more deshielded.  One can use resonance structures to explain what actually happens when an atom with a lone pair of electrons (such as N or O) is directly bonded to an aromatic ring.  My initial point was a very general one.  Clearly there are not 7 identical hydrogens in your molecule; therefore, the peak must be the result of hydrogens which are close but not necessarily equal in chemical shift.