What could be the compound in this spectra with peaks at 154 and 154+2?

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Discussion Overview

The discussion revolves around the analysis of a mass spectrum and infrared (IR) spectrum to identify an unknown compound, with a focus on interpreting specific peaks and their implications for the molecular structure. The analysis includes considerations of functional groups, isotopic patterns, and NMR data.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests the compound might be an ester with an alkyl chloride based on the observed spectra.
  • Another participant notes a strong IR band at ~1700 cm-1 indicating the presence of a carbonyl oxygen, and mentions that a band at ~1200 cm-1 is indicative of a saturated ester.
  • The same participant points out that a band at ~2900 cm-1 also suggests the presence of an ester.
  • In the mass spectrum, the molecular ion peak at 154 and the M+2 peak suggest the presence of chlorine, with a 3:1 peak ratio attributed to the isotopes 35Cl and 37Cl.
  • There is a claim that the peak at 118 indicates the loss of HCl, and a participant discusses the implications of this loss on the expected mass spectrum peaks.
  • Another participant questions whether a similar pair of peaks at 118 and 118+2 should be present if HCl is lost, indicating uncertainty about the expected results.
  • A later reply argues that there should not be a significant 118+2 peak because the loss of Cl would eliminate the presence of the 37Cl isotope, thus affecting the peak ratio.

Areas of Agreement / Disagreement

Participants express differing views on the implications of the mass spectrum peaks, particularly regarding the expected presence of peaks at 118 and 118+2 after the loss of HCl. The discussion remains unresolved with competing interpretations of the data.

Contextual Notes

Participants rely on various spectral interpretations, but there are unresolved assumptions regarding the relationships between the peaks and the molecular structure. The discussion does not clarify the exact nature of the compound due to differing interpretations of the spectral data.

Respect-rometry
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Hi guys

As part of my degree I've got to analyses a set of spectras unknown compounds. I've managed to do them all so far, but seem to be struggling on this one particular set.

Here's the spectra that I have to analyse: http://imgur.com/a/oVNYe

So far I think it might be an ester with a Alkyl chloride in it.

Any help is greatly appreciated!
 
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Please elaborate on what you see and how you get to the conclusions.
 
Borek said:
Please elaborate on what you see and how you get to the conclusions.
Sure.

Strong IR band at ~1700 indicates presence of carbonyl oxygen. In a Spectroscopy book I've got from the library, the band at ~1200 is supposedly indicative of a saturated ester. The band at ~2900 also suggests an ester

In the mass spec. The molecular ion peak is 154, with an M+2 showing a +2 isotope is present. The 3:1 peak ratio shows its Chlorine due to the 75:25 relative abundances of 35Cl& 37Cl. The peak at 118 is indicative of loss of HCl

There is a peak at 43 which I thought what a C-H group with two methyl groups and a C=O group attached. This is because there is a multiplet peak in the 1H NMR with 7 peaks and an integration of 1. So that would come from the H atom coupling to the two equivalent methyl groups.

The 13C NMR shows which environments are CH3, CH2, CH and quaternary C environments.

This is what I've got so far, so any help would be great
 
Respect-rometry said:
The peak at 118 is indicative of loss of HCl

MS is not something I feel confident about, but if you have peaks at 154 and 154+2, and HCl is lost, shouldn't you have a similar pair at 118 and 118+2?
 
Borek said:
MS is not something I feel confident about, but if you have peaks at 154 and 154+2, and HCl is lost, shouldn't you have a similar pair at 118 and 118+2?
No there shouldn't be a significant 118+2 peak, because Cl is being lost and so the 37Cl isotope won't be present anymore. Hence there is no 3:1 peak ratio in the mass spectra at 118 & 120
 

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