Laura asks…

How many signals would 2,3 – dimethylpentane have in it’s 1H NMR spectrum?

Would it be 5? thanks!
So the 3 protons at C4 and the 3 protons on the methyl group at C3 are not equivalent?

admin answers:

I counted 6 signals:

6 equivalent protons on carbon 1 and the methyl group on 2
1 proton on carbon 2
1 proton on carbon 3
3 protons on the methyl group on carbon 3
2 protons on carbon 4
and 3 protons on carbon 5

My guess is unless you have one fine NMR, a lot of it would just come out looking jumbled because it’s a rather uniform compound. I’m no expert on NMR though.

Betty asks…

Propose a structure that is consistent with the set of 1H NMR data.?

Propose a structure that is consistent with the set of 1H NMR data.

C4H10O2 δ (ppm) Splitting Integration
3.25 s 6H
3.45 s 4H

admin answers:

Since you have the empirical formula, calculate the degree of unsaturation: 4+1 – 10/2 = 0 DOU. Evidently these are alcohol or ether oxygens; either is consistent with ~3.5 ppm downfield signals. There are 4 carbons, but only two different signals, so there are probably two pairs of equivalent carbons, a pair of CH2 secondary carbons and a pair of CH3 primary carbons. This:
H3C-O-CH2-CH2-O-CH3

is almost correct, except that the 3.45 ppm signal would be a triplet, not a singlet. I don’t think there is a structure that satisfies your data, unless you’re using an old low frequency NMR and the triplet appears to be a singlet.

U

Sandra asks…

Determine the number of signals you would expect to see in the 1H-NMR spectrum of 3-Methyl Pentane?

Any help would be appreciated.
Thanks

admin answers:

Triplet of 6H (methyl groups); doublet of 3H (methyl at C3), multiplet of 1H (methine proton) and doublet of quartets of 4H (methylene protons).

You could try

http://www.nmrdb.org/predictor

Ken asks…

What do the 1H and 13C NMR spectra look like for doubly carbonyl labelled glycine?

I am a physics student that is looking at obtaining an NMR spectrum of doubly labelled glycine and I would like to know what to expect. I would like to see the high field NMR spectrum of glycine that has both its carbons replaced with carbon-13 – both the proton and carbon-13 spectra. In particular, I’d like to know the J coupling constants and see the spectra obtained.

admin answers:

Have a look at the images that come up from Googling nrm of glycine,I think you will find your answer there

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