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Homework Help: Organic Spectroscopy Help

  1. Oct 7, 2014 #1
    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!
  2. jcsd
  3. Oct 8, 2014 #2


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    Staff: Mentor

    Please elaborate on what you see and how you get to the conclusions.
  4. Oct 8, 2014 #3

    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
  5. Oct 8, 2014 #4


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    Staff: Mentor

    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?
  6. Oct 8, 2014 #5
    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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