Why Aren't Splitting Patterns & Integrations for Red & Blue Protons Different?

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SUMMARY

The discussion clarifies the confusion surrounding the splitting patterns and integrations of red and blue protons in a specific organic compound. The red protons exhibit a triplet splitting pattern with an integration of 6 H due to their chemical equivalence and the n + 1 rule, where n equals the 2 adjacent protons. Conversely, the blue protons show a quintet splitting pattern with an integration of 4 H, resulting from the contributions of adjacent carbons, where n equals 3 from one carbon and 1 from another, leading to a total of 5. This analysis is essential for understanding NMR spectroscopy in organic chemistry.

PREREQUISITES
  • Understanding of NMR spectroscopy principles
  • Familiarity with the n + 1 rule in splitting patterns
  • Knowledge of chemical equivalence in protons
  • Basic concepts of organic chemistry structures
NEXT STEPS
  • Study the n + 1 rule in detail for NMR splitting patterns
  • Explore chemical equivalence and its implications in NMR analysis
  • Learn about the interpretation of NMR spectra for complex organic compounds
  • Investigate the effects of adjacent protons on splitting patterns in NMR
USEFUL FOR

Organic chemists, students studying NMR spectroscopy, and anyone involved in interpreting splitting patterns in organic compounds will benefit from this discussion.

MermaidWonders
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View attachment 8839

For the colourfully-annotated compound above, why aren't the splitting patterns and integrations for the red and blue set of protons "pentet, 6 H" and "octet, 4 H", respectively?
 

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MermaidWonders said:
For the colourfully-annotated compound above, why aren't the splitting patterns and integrations for the red and blue set of protons "pentet, 6 H" and "octet, 4 H", respectively?

Never mind. I see why.
 
MermaidWonders said:
Never mind. I see why.
I'm curious. Would you be willing to share your solution?

-Dan
 
topsquark said:
I'm curious. Would you be willing to share your solution?

-Dan

Hi,

Sorry for the super late reply. Just saw this.

When I first came across that question, I was very confused as to why my professor had put "6 H, t" and "4 H, quintet" for the splitting patterns and peak integrations for the red and blue set of protons, respectively (as in the screenshot), so I tried to look at that question in a "different" way. If we start by looking at the red protons branching out from either of the 2 carbons, we see that there are 2 protons coming off of the adjacent carbon (whether you are looking at the top or bottom adjacent carbon). Because all 6 of the red protons are chemically-equivalent, it makes sense for the splitting pattern to be a triplet according to the n + 1 rule, where n = 2 for the adjacent C. Next, if we look at the blue set of protons, we are in a similar situation. All 4 of the blue protons are chemically-equivalent, and a quintet splitting pattern comes from the fact that the "top" OR "bottom" adjacent C (the C's with red protons branching off of it) gives n = 3 AND the other adjacent C (the one with a green proton branching off of it) gives n = 1, so together, n + 1 = 4 + 1 = 5 --> quintet.

Hope what I said sort of makes sense. I'm really no expert in organic chemistry myself, but at least this is the process I had to go through to understand that solution! :(
 

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