[Doctor proctor]

I am attempting to read an NMR test on a compound with the Following  formula; C24H34O5



I am only counting 21 peaks, which is not matching up with the formula for the compound. I am not sure if there are overlapping peaks which I'm not accounting for, whether I am integrating improperly, or if my understanding of chemical shift is incorrect. If any one could please help me clarify what I'm doing wrong, and.whether or not the NMR matches the compound, I would greatly appreciate it.

[granolagricola]

It is very hard to see how that NMR could possibly match the formula you posted.

[kriggy]

It is very hard to see how that NMR could possibly match the formula you posted.

Can you explain this please? My understanding of NMR interpretation is pretty porr so I could learn something

btw 21 peaks..isnt it that atoms with equivalent electron neighbourhood show as 1 peak? Like propane should give only 1 peaks, 1 for -CH₂- and one for two -CH₃ groups

[Borek]

There is no simple relationship between number of peaks and number of protons.

[Dan]

The integration is under 24, implying that there are fewer than 24 H.

Note that the peak at 7.3 is (probably) residual chloroform in the CDCl₃. That would put the total at ~20H. The peaks either side of 1 ppm have not been integrated. Fast-exchanging protons might not be resolved.

The information provided is inadequate for identification. 13C NMR, 2D NMR correlation experiments and mass spec are really the minimum requirement for starting to make a convincing argument.

[Doctor proctor]

The integration is under 24, implying that there are fewer than 24 H.

Note that the peak at 7.3 is (probably) residual chloroform in the CDCl₃. That would put the total at ~20H. The peaks either side of 1 ppm have not been integrated. Fast-exchanging protons might not be resolved.

The information provided is inadequate for identification. 13C NMR, 2D NMR correlation experiments and mass spec are really the minimum requirement for starting to make a convincing argument.

Right, I understand 1D NMR is at best a very rough guess of a compound, but, if we're only worried about protons, isn't this test enough to state that this compound does not contain 34 H, or no, and if so, why? I understand I'm asking alot, and I appreciate the help guys, thanks!!

[orgopete]

I am inclined to think this compound cannot be an H34 compound. Because the integration is so distant to 34 hydrogens, I cannot readily think there is some kind of symmetry to double the existing integral to come to 34.

In our undergraduate lab, I often observed quite poor quality spectra. Although there may have been broadening or other factors that made the spectra more difficult to interpret, the integrals or integral rations remained reasonably accurate (within the scope of integral accuracy). With this spectrum, several peaks and integrals are sufficiently discreet that it is difficult to suggest a doubling or a systematic error sufficient to justify the presence of 34 protons.

[Doctor proctor]

I am inclined to think this compound cannot be an H34 compound. Because the integration is so distant to 34 hydrogens, I cannot readily think there is some kind of symmetry to double the existing integral to come to 34.

In our undergraduate lab, I often observed quite poor quality spectra. Although there may have been broadening or other factors that made the spectra more difficult to interpret, the integrals or integral rations remained reasonably accurate (within the scope of integral accuracy). With this spectrum, several peaks and integrals are sufficiently discreet that it is difficult to suggest a doubling or a systematic error sufficient to justify the presence of 34 protons.

Yeah, that was my conclusion as well...thanks for your help, now I have to start from scratch..