How Do You Apply Pople Notation to Complex Spin Systems Like in 1-Bromobutane?

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SUMMARY

The discussion focuses on the application of Pople Notation to complex spin systems, specifically in the context of 1-bromobutane (CH3-CH2-CH2-CH2-Br). The proper designation for this molecule is A3BB'CC'DD', indicating the presence of four unique spin systems. The notation reflects the unique characteristics of the protons, including their magnetic inequivalence. The user expresses confusion over how to represent multiple spin systems, but the consensus is that multiple letters can be utilized to accurately describe the system.

PREREQUISITES
  • Understanding of NMR spectroscopy principles
  • Familiarity with Pople Notation and its application
  • Knowledge of spin systems and multiplet patterns
  • Basic organic chemistry, particularly regarding molecular structures
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  • Study the detailed descriptions of Pople Notation at the provided links
  • Learn about the significance of magnetic inequivalence in NMR
  • Explore advanced NMR techniques for complex spin systems
  • Investigate the implications of enantiotopic and diastereotopic protons in NMR analysis
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Chemists, particularly those specializing in NMR spectroscopy, organic chemists, and students seeking to deepen their understanding of complex spin systems and Pople Notation.

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NMR "Pople Notation" HELP!

All the examples in my textbook show molecules that have only three sets of multiplets (AX, AB, ABX, or AMX first oder spin systems). But what if I have a molecule with more than 3 spin systems, for example in 1-bromobutane:

CH3-CH2-CH2-CH2-Br (there is a triplet, sextet, quintet, and triplet).

Each proton is unique, i.e., no chemically equivalent shift H's, no magnetically equivalent protons, enantiotopic or diastereotopic protons.

For this example, there is 4 spin systems, so do I have to describe it using 4 letters, but that seems impossible. I'm confused.

So far, I think it is this (reading left to right of the molecule): A3 B2 B2 X2

Someone please explain to me Pople notation. Thank you.
 
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scarecrow said:
All the examples in my textbook show molecules that have only three sets of multiplets (AX, AB, ABX, or AMX first oder spin systems). But what if I have a molecule with more than 3 spin systems, for example in 1-bromobutane:

CH3-CH2-CH2-CH2-Br (there is a triplet, sextet, quintet, and triplet).

Each proton is unique, i.e., no chemically equivalent shift H's, no magnetically equivalent protons, enantiotopic or diastereotopic protons.

For this example, there is 4 spin systems, so do I have to describe it using 4 letters, but that seems impossible. I'm confused.

So far, I think it is this (reading left to right of the molecule): A3 B2 B2 X2

Someone please explain to me Pople notation. Thank you.

You can see a detailed description of the Pople system at: http://www.chem.wisc.edu/areas/reich/nmr/05-hmr-07-pople.htm and http://www.chem.wisc.edu/areas/reich/nmr/05-hmr-08-symmetry.htm Any number of letters may be used.

The proper designation of 1-bromobutane is A3BB'CC'DD'. One could also use A3BB'CC'XX' since the CH2Br protons are quite far away from the others. The primes (BB') are there becasue the two B, two C and two D(X) protons are magnetically inequivalent. See: http://www.chem.wisc.edu/areas/reich/nmr/05-hmr-14-a2b2.htm
 
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