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

Click For Summary
SUMMARY

The discussion centers on the analysis of a mass spectrum with peaks at 154 and 156, suggesting the presence of a compound likely to be an ester with an alkyl chloride. Key indicators include a strong IR band at ~1700 cm-1 for carbonyl oxygen, a band at ~1200 cm-1 indicative of a saturated ester, and a peak at 2900 cm-1 also suggesting ester functionality. The molecular ion peak at 154 confirms the presence of chlorine, supported by a 3:1 peak ratio due to the isotopes 35Cl and 37Cl. The analysis concludes that the peak at 118 indicates the loss of HCl, and no significant peak at 118+2 is expected due to the absence of the 37Cl isotope.

PREREQUISITES
  • Understanding of mass spectrometry (MS) principles and peak interpretation
  • Familiarity with infrared spectroscopy (IR) and its functional group indicators
  • Knowledge of NMR spectroscopy, particularly 1H and 13C NMR
  • Basic organic chemistry concepts, including ester and alkyl chloride structures
NEXT STEPS
  • Study mass spectrometry peak patterns and isotope effects in detail
  • Review infrared spectroscopy for functional group identification
  • Learn about 1H and 13C NMR interpretation techniques
  • Explore the chemistry of esters and alkyl chlorides for structural insights
USEFUL FOR

Chemistry students, organic chemists, and analytical chemists involved in compound identification and spectral analysis.

Respect-rometry
Messages
3
Reaction score
0
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!
 
Physics news on Phys.org
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
 

Similar threads

Graduate Understanding molecular absorption of light (UV-Vis spectroscopy)
  • · Replies 3 ·
Replies
3
Views
4K
Chemistry Ideal gas law, concentrations, mole fractions
  • · Replies 1 ·
Replies
1
Views
8K
I could really use some help picking my optional module [GameDev]
  • · Replies 2 ·
Replies
2
Views
3K
Is Option 2 the Only Subset of P(C) in This List?
  • · Replies 6 ·
Replies
6
Views
2K
Courses What is it like to work as an Astrophysicist or an Aerospace Engineer?
  • · Replies 2 ·
Replies
2
Views
2K
Admissions How to enter theoretical physics with astronomy background?
  • · Replies 2 ·
Replies
2
Views
2K
2 Unknown Currents, 1 Unknown emf, and a little confusion to boot
  • · Replies 1 ·
Replies
1
Views
4K
Medical Physicist vs Medical image processing?
  • · Replies 5 ·
Replies
5
Views
4K
Should I retake GRE for Medical Physics (Master's)
  • · Replies 2 ·
Replies
2
Views
2K
Diffusion of a species through a sphere
  • · Replies 1 ·
Replies
1
Views
4K