NMR Signals & Peaks of Di-Substituted Benzene Rings

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Discussion Overview

The discussion centers on the number of NMR signals and peaks for a di-substituted benzene ring, specifically one with a methyl group and a chlorine atom. Participants explore the application of the n+1 rule and the identification of chemically equivalent protons in the context of NMR spectroscopy.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes that there will be 3 NMR signals based on the presence of three sets of chemically equivalent protons: the methyl protons, the protons adjacent to the chlorine, and the protons adjacent to the methyl group.
  • Another participant questions the initial description of the substituents, suggesting a possible misunderstanding regarding the positions of the methyl and chlorine groups, indicating a need for clarification on whether they are ortho or para to each other.
  • A later reply confirms the correction, stating that the groups are indeed para, and provides a drawing for clarity.
  • One participant agrees with the assessment of three kinds of protons, supporting the initial claim.

Areas of Agreement / Disagreement

Participants generally agree on the identification of three kinds of protons, but there is a disagreement regarding the initial positioning of the substituents (ortho vs. para), which has been clarified in later posts.

Contextual Notes

The discussion reflects some uncertainty regarding the application of the n+1 rule and the identification of equivalent protons, which may depend on the correct understanding of the molecular structure.

FTNMR
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Thread moved from the technical forums, so no Homework Help Template is shown
How many NMR signals and peaks will there be for a di-substituted benzene ring and why?
The ring has one CH3 and and a Cl ortho to the CH3.

(This isn't a homework problem but I am running into same issue whenever I encounter rings wrt NMR)

i am specifically confused as to how to apply the n+1 rule to determine the number of peaks, with respect to two chemically equivalent protons.

But first the signals

On the above example, I think there will be 3 signals:
the 3 chemically equivalent methyl protons = signal 1
the 2 chem equiv protons on either side of the Cl = the 2nd signal
the 2 chem equiv protons on either side of the methyl = the 3rd signal

Before I ask about peaks, could someone tell me if this is correct so far?

thanks
 
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You say that the methyl is ortho to the chlorine, but from the description of the protons, it sounds like you're talking about p-chlorotoluene where the groups are para to each other. Which is correct?
 
download.png
 
Ygggdrasil said:
You say that the methyl is ortho to the chlorine, but from the description of the protons, it sounds like you're talking about p-chlorotoluene where the groups are para to each other. Which is correct?

Sorry not sure why i said ortho, yup i definitely meant para..heres drawing so its clear
 
please ignore that little grey dot above the ring.. no idea what that is (just learning chemdoodle).. thanks
 
Three kinds of protons sounds right.
 

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