Help! H-NMR Splitting with R and S

[Typical Average Student]

I'm not sure if this makes sense but I'll try to explain it the best I can:

This has to do with finding the H-NMR of a proton: Lets say there's 1 proton on each side of a proton we're trying to find the peak of, one of the adjacent protons is in R conformation and the other in S. Would the H-NMR display the peak as a triplet (if the protons are considered symmetrical) or would it display as a quadruplet (if the protons are considered different)?

I guess an example molecule would be: (1R-3S)-1,3 dibromo-2-chloro-1,3- dimethylpropane (below) and we're trying to find the peak of the hydrogen geminal to the chlorine.

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[Typical Average Student]

Oops, I have my R and S mixed up... but the concept still applies!

 

[DAT Destroyer]

I'm not sure if this makes sense but I'll try to explain it the best I can:

This has to do with finding the H-NMR of a proton: Lets say there's 1 proton on each side of a proton we're trying to find the peak of, one of the adjacent protons is in R conformation and the other in S. Would the H-NMR display the peak as a triplet (if the protons are considered symmetrical) or would it display as a quadruplet (if the protons are considered different)?

I guess an example molecule would be: (1R-3S)-1,3 dibromo-2-chloro-1,3- dimethylpropane (below) and we're trying to find the peak of the hydrogen geminal to the chlorine.

View attachment 193713

The 2 protons are equivalent adjacent to the Carbon with the Chlorine. Enantiotopic protons are equivalent in NMR....thus the signal would come in as a triplet.

Hope this helps.

Dr. Romano

 

[DrNutmeg]

I'm not sure if this makes sense but I'll try to explain it the best I can:

This has to do with finding the H-NMR of a proton: Lets say there's 1 proton on each side of a proton we're trying to find the peak of, one of the adjacent protons is in R conformation and the other in S. Would the H-NMR display the peak as a triplet (if the protons are considered symmetrical) or would it display as a quadruplet (if the protons are considered different)?

I guess an example molecule would be: (1R-3S)-1,3 dibromo-2-chloro-1,3- dimethylpropane (below) and we're trying to find the peak of the hydrogen geminal to the chlorine.

View attachment 193713

There will be one peak (a quintet) that integrates to 2.0 to account for both of the symmetrical hydrogens.

The hydrogen next to the Cl will be accounted for by a triplet that integrates to 1.0.